linux/drivers/mtd/mtdpart.c

992 lines
27 KiB

mtd: fix partition wrapper functions This patch reverts a change that may have been mistakenly included with the set of patches that introduced the new mtd api entry functions. Or perhaps I am mistaken :) The problem is in the partition wrapper functions, where the calls to the driver methods were replaced with calls to the new mtd api functions. This causes the api function to be called a second time, further down the call stack. This is not only unnecessary and redundant - because the sanity checking code and (more restrictive) bounds checks for the partition were done in the first call - but is potentially problematic and confusing. For example, the call stack for a call to mtd_read() on a partitioned device currently looks like this: mtd_read() gets struct mtd_info for the partition | +-> part_read() via the pointer assigned when the partition was created | +->mtd_read() this time gets struct mtd_info for the master | +->xyz_driver_read() via the pointer asigned by the driver It seems that this can cause a variety of problems. For example, if you want to add code to the api function that tests a value in mtd_info that is relevant only to the partition. Or (in my case) you want the driver to return a value that may be different from that returned by the mtd api function. This patch eliminates the second call to the mtd api function. It was tested on the docg4 nand driver with a subset of the api functions, but I inspected the rest and don't see any problems. Signed-off-by: Mike Dunn <mikedunn@newsguy.com> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2012-03-03 13:13:06 -08:00
mtd: fix partition wrapper functions This patch reverts a change that may have been mistakenly included with the set of patches that introduced the new mtd api entry functions. Or perhaps I am mistaken :) The problem is in the partition wrapper functions, where the calls to the driver methods were replaced with calls to the new mtd api functions. This causes the api function to be called a second time, further down the call stack. This is not only unnecessary and redundant - because the sanity checking code and (more restrictive) bounds checks for the partition were done in the first call - but is potentially problematic and confusing. For example, the call stack for a call to mtd_read() on a partitioned device currently looks like this: mtd_read() gets struct mtd_info for the partition | +-> part_read() via the pointer assigned when the partition was created | +->mtd_read() this time gets struct mtd_info for the master | +->xyz_driver_read() via the pointer asigned by the driver It seems that this can cause a variety of problems. For example, if you want to add code to the api function that tests a value in mtd_info that is relevant only to the partition. Or (in my case) you want the driver to return a value that may be different from that returned by the mtd api function. This patch eliminates the second call to the mtd api function. It was tested on the docg4 nand driver with a subset of the api functions, but I inspected the rest and don't see any problems. Signed-off-by: Mike Dunn <mikedunn@newsguy.com> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2012-03-03 13:13:06 -08:00
mtd: fix partition wrapper functions This patch reverts a change that may have been mistakenly included with the set of patches that introduced the new mtd api entry functions. Or perhaps I am mistaken :) The problem is in the partition wrapper functions, where the calls to the driver methods were replaced with calls to the new mtd api functions. This causes the api function to be called a second time, further down the call stack. This is not only unnecessary and redundant - because the sanity checking code and (more restrictive) bounds checks for the partition were done in the first call - but is potentially problematic and confusing. For example, the call stack for a call to mtd_read() on a partitioned device currently looks like this: mtd_read() gets struct mtd_info for the partition | +-> part_read() via the pointer assigned when the partition was created | +->mtd_read() this time gets struct mtd_info for the master | +->xyz_driver_read() via the pointer asigned by the driver It seems that this can cause a variety of problems. For example, if you want to add code to the api function that tests a value in mtd_info that is relevant only to the partition. Or (in my case) you want the driver to return a value that may be different from that returned by the mtd api function. This patch eliminates the second call to the mtd api function. It was tested on the docg4 nand driver with a subset of the api functions, but I inspected the rest and don't see any problems. Signed-off-by: Mike Dunn <mikedunn@newsguy.com> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2012-03-03 13:13:06 -08:00
[MTD] Rework the out of band handling completely Hopefully the last iteration on this! The handling of out of band data on NAND was accompanied by tons of fruitless discussions and halfarsed patches to make it work for a particular problem. Sufficiently annoyed by I all those "I know it better" mails and the resonable amount of discarded "it solves my problem" patches, I finally decided to go for the big rework. After removing the _ecc variants of mtd read/write functions the solution to satisfy the various requirements was to refactor the read/write _oob functions in mtd. The major change is that read/write_oob now takes a pointer to an operation descriptor structure "struct mtd_oob_ops".instead of having a function with at least seven arguments. read/write_oob which should probably renamed to a more descriptive name, can do the following tasks: - read/write out of band data - read/write data content and out of band data - read/write raw data content and out of band data (ecc disabled) struct mtd_oob_ops has a mode field, which determines the oob handling mode. Aside of the MTD_OOB_RAW mode, which is intended to be especially for diagnostic purposes and some internal functions e.g. bad block table creation, the other two modes are for mtd clients: MTD_OOB_PLACE puts/gets the given oob data exactly to/from the place which is described by the ooboffs and ooblen fields of the mtd_oob_ops strcuture. It's up to the caller to make sure that the byte positions are not used by the ECC placement algorithms. MTD_OOB_AUTO puts/gets the given oob data automaticaly to/from the places in the out of band area which are described by the oobfree tuples in the ecclayout data structre which is associated to the devicee. The decision whether data plus oob or oob only handling is done depends on the setting of the datbuf member of the data structure. When datbuf == NULL then the internal read/write_oob functions are selected, otherwise the read/write data routines are invoked. Tested on a few platforms with all variants. Please be aware of possible regressions for your particular device / application scenario Disclaimer: Any whining will be ignored from those who just contributed "hot air blurb" and never sat down to tackle the underlying problem of the mess in the NAND driver grown over time and the big chunk of work to fix up the existing users. The problem was not the holiness of the existing MTD interfaces. The problems was the lack of time to go for the big overhaul. It's easy to add more mess to the existing one, but it takes alot of effort to go for a real solution. Improvements and bugfixes are welcome! Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2006-05-29 03:26:58 +02:00
[MTD] Rework the out of band handling completely Hopefully the last iteration on this! The handling of out of band data on NAND was accompanied by tons of fruitless discussions and halfarsed patches to make it work for a particular problem. Sufficiently annoyed by I all those "I know it better" mails and the resonable amount of discarded "it solves my problem" patches, I finally decided to go for the big rework. After removing the _ecc variants of mtd read/write functions the solution to satisfy the various requirements was to refactor the read/write _oob functions in mtd. The major change is that read/write_oob now takes a pointer to an operation descriptor structure "struct mtd_oob_ops".instead of having a function with at least seven arguments. read/write_oob which should probably renamed to a more descriptive name, can do the following tasks: - read/write out of band data - read/write data content and out of band data - read/write raw data content and out of band data (ecc disabled) struct mtd_oob_ops has a mode field, which determines the oob handling mode. Aside of the MTD_OOB_RAW mode, which is intended to be especially for diagnostic purposes and some internal functions e.g. bad block table creation, the other two modes are for mtd clients: MTD_OOB_PLACE puts/gets the given oob data exactly to/from the place which is described by the ooboffs and ooblen fields of the mtd_oob_ops strcuture. It's up to the caller to make sure that the byte positions are not used by the ECC placement algorithms. MTD_OOB_AUTO puts/gets the given oob data automaticaly to/from the places in the out of band area which are described by the oobfree tuples in the ecclayout data structre which is associated to the devicee. The decision whether data plus oob or oob only handling is done depends on the setting of the datbuf member of the data structure. When datbuf == NULL then the internal read/write_oob functions are selected, otherwise the read/write data routines are invoked. Tested on a few platforms with all variants. Please be aware of possible regressions for your particular device / application scenario Disclaimer: Any whining will be ignored from those who just contributed "hot air blurb" and never sat down to tackle the underlying problem of the mess in the NAND driver grown over time and the big chunk of work to fix up the existing users. The problem was not the holiness of the existing MTD interfaces. The problems was the lack of time to go for the big overhaul. It's easy to add more mess to the existing one, but it takes alot of effort to go for a real solution. Improvements and bugfixes are welcome! Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2006-05-29 03:26:58 +02:00
[MTD] Rework the out of band handling completely Hopefully the last iteration on this! The handling of out of band data on NAND was accompanied by tons of fruitless discussions and halfarsed patches to make it work for a particular problem. Sufficiently annoyed by I all those "I know it better" mails and the resonable amount of discarded "it solves my problem" patches, I finally decided to go for the big rework. After removing the _ecc variants of mtd read/write functions the solution to satisfy the various requirements was to refactor the read/write _oob functions in mtd. The major change is that read/write_oob now takes a pointer to an operation descriptor structure "struct mtd_oob_ops".instead of having a function with at least seven arguments. read/write_oob which should probably renamed to a more descriptive name, can do the following tasks: - read/write out of band data - read/write data content and out of band data - read/write raw data content and out of band data (ecc disabled) struct mtd_oob_ops has a mode field, which determines the oob handling mode. Aside of the MTD_OOB_RAW mode, which is intended to be especially for diagnostic purposes and some internal functions e.g. bad block table creation, the other two modes are for mtd clients: MTD_OOB_PLACE puts/gets the given oob data exactly to/from the place which is described by the ooboffs and ooblen fields of the mtd_oob_ops strcuture. It's up to the caller to make sure that the byte positions are not used by the ECC placement algorithms. MTD_OOB_AUTO puts/gets the given oob data automaticaly to/from the places in the out of band area which are described by the oobfree tuples in the ecclayout data structre which is associated to the devicee. The decision whether data plus oob or oob only handling is done depends on the setting of the datbuf member of the data structure. When datbuf == NULL then the internal read/write_oob functions are selected, otherwise the read/write data routines are invoked. Tested on a few platforms with all variants. Please be aware of possible regressions for your particular device / application scenario Disclaimer: Any whining will be ignored from those who just contributed "hot air blurb" and never sat down to tackle the underlying problem of the mess in the NAND driver grown over time and the big chunk of work to fix up the existing users. The problem was not the holiness of the existing MTD interfaces. The problems was the lack of time to go for the big overhaul. It's easy to add more mess to the existing one, but it takes alot of effort to go for a real solution. Improvements and bugfixes are welcome! Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2006-05-29 03:26:58 +02:00
[MTD] Rework the out of band handling completely Hopefully the last iteration on this! The handling of out of band data on NAND was accompanied by tons of fruitless discussions and halfarsed patches to make it work for a particular problem. Sufficiently annoyed by I all those "I know it better" mails and the resonable amount of discarded "it solves my problem" patches, I finally decided to go for the big rework. After removing the _ecc variants of mtd read/write functions the solution to satisfy the various requirements was to refactor the read/write _oob functions in mtd. The major change is that read/write_oob now takes a pointer to an operation descriptor structure "struct mtd_oob_ops".instead of having a function with at least seven arguments. read/write_oob which should probably renamed to a more descriptive name, can do the following tasks: - read/write out of band data - read/write data content and out of band data - read/write raw data content and out of band data (ecc disabled) struct mtd_oob_ops has a mode field, which determines the oob handling mode. Aside of the MTD_OOB_RAW mode, which is intended to be especially for diagnostic purposes and some internal functions e.g. bad block table creation, the other two modes are for mtd clients: MTD_OOB_PLACE puts/gets the given oob data exactly to/from the place which is described by the ooboffs and ooblen fields of the mtd_oob_ops strcuture. It's up to the caller to make sure that the byte positions are not used by the ECC placement algorithms. MTD_OOB_AUTO puts/gets the given oob data automaticaly to/from the places in the out of band area which are described by the oobfree tuples in the ecclayout data structre which is associated to the devicee. The decision whether data plus oob or oob only handling is done depends on the setting of the datbuf member of the data structure. When datbuf == NULL then the internal read/write_oob functions are selected, otherwise the read/write data routines are invoked. Tested on a few platforms with all variants. Please be aware of possible regressions for your particular device / application scenario Disclaimer: Any whining will be ignored from those who just contributed "hot air blurb" and never sat down to tackle the underlying problem of the mess in the NAND driver grown over time and the big chunk of work to fix up the existing users. The problem was not the holiness of the existing MTD interfaces. The problems was the lack of time to go for the big overhaul. It's easy to add more mess to the existing one, but it takes alot of effort to go for a real solution. Improvements and bugfixes are welcome! Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2006-05-29 03:26:58 +02:00
mtd: fix partition wrapper functions This patch reverts a change that may have been mistakenly included with the set of patches that introduced the new mtd api entry functions. Or perhaps I am mistaken :) The problem is in the partition wrapper functions, where the calls to the driver methods were replaced with calls to the new mtd api functions. This causes the api function to be called a second time, further down the call stack. This is not only unnecessary and redundant - because the sanity checking code and (more restrictive) bounds checks for the partition were done in the first call - but is potentially problematic and confusing. For example, the call stack for a call to mtd_read() on a partitioned device currently looks like this: mtd_read() gets struct mtd_info for the partition | +-> part_read() via the pointer assigned when the partition was created | +->mtd_read() this time gets struct mtd_info for the master | +->xyz_driver_read() via the pointer asigned by the driver It seems that this can cause a variety of problems. For example, if you want to add code to the api function that tests a value in mtd_info that is relevant only to the partition. Or (in my case) you want the driver to return a value that may be different from that returned by the mtd api function. This patch eliminates the second call to the mtd api function. It was tested on the docg4 nand driver with a subset of the api functions, but I inspected the rest and don't see any problems. Signed-off-by: Mike Dunn <mikedunn@newsguy.com> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2012-03-03 13:13:06 -08:00
mtd: fix partition wrapper functions This patch reverts a change that may have been mistakenly included with the set of patches that introduced the new mtd api entry functions. Or perhaps I am mistaken :) The problem is in the partition wrapper functions, where the calls to the driver methods were replaced with calls to the new mtd api functions. This causes the api function to be called a second time, further down the call stack. This is not only unnecessary and redundant - because the sanity checking code and (more restrictive) bounds checks for the partition were done in the first call - but is potentially problematic and confusing. For example, the call stack for a call to mtd_read() on a partitioned device currently looks like this: mtd_read() gets struct mtd_info for the partition | +-> part_read() via the pointer assigned when the partition was created | +->mtd_read() this time gets struct mtd_info for the master | +->xyz_driver_read() via the pointer asigned by the driver It seems that this can cause a variety of problems. For example, if you want to add code to the api function that tests a value in mtd_info that is relevant only to the partition. Or (in my case) you want the driver to return a value that may be different from that returned by the mtd api function. This patch eliminates the second call to the mtd api function. It was tested on the docg4 nand driver with a subset of the api functions, but I inspected the rest and don't see any problems. Signed-off-by: Mike Dunn <mikedunn@newsguy.com> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2012-03-03 13:13:06 -08:00
mtd: fix partition wrapper functions This patch reverts a change that may have been mistakenly included with the set of patches that introduced the new mtd api entry functions. Or perhaps I am mistaken :) The problem is in the partition wrapper functions, where the calls to the driver methods were replaced with calls to the new mtd api functions. This causes the api function to be called a second time, further down the call stack. This is not only unnecessary and redundant - because the sanity checking code and (more restrictive) bounds checks for the partition were done in the first call - but is potentially problematic and confusing. For example, the call stack for a call to mtd_read() on a partitioned device currently looks like this: mtd_read() gets struct mtd_info for the partition | +-> part_read() via the pointer assigned when the partition was created | +->mtd_read() this time gets struct mtd_info for the master | +->xyz_driver_read() via the pointer asigned by the driver It seems that this can cause a variety of problems. For example, if you want to add code to the api function that tests a value in mtd_info that is relevant only to the partition. Or (in my case) you want the driver to return a value that may be different from that returned by the mtd api function. This patch eliminates the second call to the mtd api function. It was tested on the docg4 nand driver with a subset of the api functions, but I inspected the rest and don't see any problems. Signed-off-by: Mike Dunn <mikedunn@newsguy.com> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2012-03-03 13:13:06 -08:00
mtd: fix partition wrapper functions This patch reverts a change that may have been mistakenly included with the set of patches that introduced the new mtd api entry functions. Or perhaps I am mistaken :) The problem is in the partition wrapper functions, where the calls to the driver methods were replaced with calls to the new mtd api functions. This causes the api function to be called a second time, further down the call stack. This is not only unnecessary and redundant - because the sanity checking code and (more restrictive) bounds checks for the partition were done in the first call - but is potentially problematic and confusing. For example, the call stack for a call to mtd_read() on a partitioned device currently looks like this: mtd_read() gets struct mtd_info for the partition | +-> part_read() via the pointer assigned when the partition was created | +->mtd_read() this time gets struct mtd_info for the master | +->xyz_driver_read() via the pointer asigned by the driver It seems that this can cause a variety of problems. For example, if you want to add code to the api function that tests a value in mtd_info that is relevant only to the partition. Or (in my case) you want the driver to return a value that may be different from that returned by the mtd api function. This patch eliminates the second call to the mtd api function. It was tested on the docg4 nand driver with a subset of the api functions, but I inspected the rest and don't see any problems. Signed-off-by: Mike Dunn <mikedunn@newsguy.com> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2012-03-03 13:13:06 -08:00
[MTD] Rework the out of band handling completely Hopefully the last iteration on this! The handling of out of band data on NAND was accompanied by tons of fruitless discussions and halfarsed patches to make it work for a particular problem. Sufficiently annoyed by I all those "I know it better" mails and the resonable amount of discarded "it solves my problem" patches, I finally decided to go for the big rework. After removing the _ecc variants of mtd read/write functions the solution to satisfy the various requirements was to refactor the read/write _oob functions in mtd. The major change is that read/write_oob now takes a pointer to an operation descriptor structure "struct mtd_oob_ops".instead of having a function with at least seven arguments. read/write_oob which should probably renamed to a more descriptive name, can do the following tasks: - read/write out of band data - read/write data content and out of band data - read/write raw data content and out of band data (ecc disabled) struct mtd_oob_ops has a mode field, which determines the oob handling mode. Aside of the MTD_OOB_RAW mode, which is intended to be especially for diagnostic purposes and some internal functions e.g. bad block table creation, the other two modes are for mtd clients: MTD_OOB_PLACE puts/gets the given oob data exactly to/from the place which is described by the ooboffs and ooblen fields of the mtd_oob_ops strcuture. It's up to the caller to make sure that the byte positions are not used by the ECC placement algorithms. MTD_OOB_AUTO puts/gets the given oob data automaticaly to/from the places in the out of band area which are described by the oobfree tuples in the ecclayout data structre which is associated to the devicee. The decision whether data plus oob or oob only handling is done depends on the setting of the datbuf member of the data structure. When datbuf == NULL then the internal read/write_oob functions are selected, otherwise the read/write data routines are invoked. Tested on a few platforms with all variants. Please be aware of possible regressions for your particular device / application scenario Disclaimer: Any whining will be ignored from those who just contributed "hot air blurb" and never sat down to tackle the underlying problem of the mess in the NAND driver grown over time and the big chunk of work to fix up the existing users. The problem was not the holiness of the existing MTD interfaces. The problems was the lack of time to go for the big overhaul. It's easy to add more mess to the existing one, but it takes alot of effort to go for a real solution. Improvements and bugfixes are welcome! Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2006-05-29 03:26:58 +02:00
[MTD] Rework the out of band handling completely Hopefully the last iteration on this! The handling of out of band data on NAND was accompanied by tons of fruitless discussions and halfarsed patches to make it work for a particular problem. Sufficiently annoyed by I all those "I know it better" mails and the resonable amount of discarded "it solves my problem" patches, I finally decided to go for the big rework. After removing the _ecc variants of mtd read/write functions the solution to satisfy the various requirements was to refactor the read/write _oob functions in mtd. The major change is that read/write_oob now takes a pointer to an operation descriptor structure "struct mtd_oob_ops".instead of having a function with at least seven arguments. read/write_oob which should probably renamed to a more descriptive name, can do the following tasks: - read/write out of band data - read/write data content and out of band data - read/write raw data content and out of band data (ecc disabled) struct mtd_oob_ops has a mode field, which determines the oob handling mode. Aside of the MTD_OOB_RAW mode, which is intended to be especially for diagnostic purposes and some internal functions e.g. bad block table creation, the other two modes are for mtd clients: MTD_OOB_PLACE puts/gets the given oob data exactly to/from the place which is described by the ooboffs and ooblen fields of the mtd_oob_ops strcuture. It's up to the caller to make sure that the byte positions are not used by the ECC placement algorithms. MTD_OOB_AUTO puts/gets the given oob data automaticaly to/from the places in the out of band area which are described by the oobfree tuples in the ecclayout data structre which is associated to the devicee. The decision whether data plus oob or oob only handling is done depends on the setting of the datbuf member of the data structure. When datbuf == NULL then the internal read/write_oob functions are selected, otherwise the read/write data routines are invoked. Tested on a few platforms with all variants. Please be aware of possible regressions for your particular device / application scenario Disclaimer: Any whining will be ignored from those who just contributed "hot air blurb" and never sat down to tackle the underlying problem of the mess in the NAND driver grown over time and the big chunk of work to fix up the existing users. The problem was not the holiness of the existing MTD interfaces. The problems was the lack of time to go for the big overhaul. It's easy to add more mess to the existing one, but it takes alot of effort to go for a real solution. Improvements and bugfixes are welcome! Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2006-05-29 03:26:58 +02:00
[MTD] Rework the out of band handling completely Hopefully the last iteration on this! The handling of out of band data on NAND was accompanied by tons of fruitless discussions and halfarsed patches to make it work for a particular problem. Sufficiently annoyed by I all those "I know it better" mails and the resonable amount of discarded "it solves my problem" patches, I finally decided to go for the big rework. After removing the _ecc variants of mtd read/write functions the solution to satisfy the various requirements was to refactor the read/write _oob functions in mtd. The major change is that read/write_oob now takes a pointer to an operation descriptor structure "struct mtd_oob_ops".instead of having a function with at least seven arguments. read/write_oob which should probably renamed to a more descriptive name, can do the following tasks: - read/write out of band data - read/write data content and out of band data - read/write raw data content and out of band data (ecc disabled) struct mtd_oob_ops has a mode field, which determines the oob handling mode. Aside of the MTD_OOB_RAW mode, which is intended to be especially for diagnostic purposes and some internal functions e.g. bad block table creation, the other two modes are for mtd clients: MTD_OOB_PLACE puts/gets the given oob data exactly to/from the place which is described by the ooboffs and ooblen fields of the mtd_oob_ops strcuture. It's up to the caller to make sure that the byte positions are not used by the ECC placement algorithms. MTD_OOB_AUTO puts/gets the given oob data automaticaly to/from the places in the out of band area which are described by the oobfree tuples in the ecclayout data structre which is associated to the devicee. The decision whether data plus oob or oob only handling is done depends on the setting of the datbuf member of the data structure. When datbuf == NULL then the internal read/write_oob functions are selected, otherwise the read/write data routines are invoked. Tested on a few platforms with all variants. Please be aware of possible regressions for your particular device / application scenario Disclaimer: Any whining will be ignored from those who just contributed "hot air blurb" and never sat down to tackle the underlying problem of the mess in the NAND driver grown over time and the big chunk of work to fix up the existing users. The problem was not the holiness of the existing MTD interfaces. The problems was the lack of time to go for the big overhaul. It's easy to add more mess to the existing one, but it takes alot of effort to go for a real solution. Improvements and bugfixes are welcome! Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2006-05-29 03:26:58 +02:00
[MTD] Rework the out of band handling completely Hopefully the last iteration on this! The handling of out of band data on NAND was accompanied by tons of fruitless discussions and halfarsed patches to make it work for a particular problem. Sufficiently annoyed by I all those "I know it better" mails and the resonable amount of discarded "it solves my problem" patches, I finally decided to go for the big rework. After removing the _ecc variants of mtd read/write functions the solution to satisfy the various requirements was to refactor the read/write _oob functions in mtd. The major change is that read/write_oob now takes a pointer to an operation descriptor structure "struct mtd_oob_ops".instead of having a function with at least seven arguments. read/write_oob which should probably renamed to a more descriptive name, can do the following tasks: - read/write out of band data - read/write data content and out of band data - read/write raw data content and out of band data (ecc disabled) struct mtd_oob_ops has a mode field, which determines the oob handling mode. Aside of the MTD_OOB_RAW mode, which is intended to be especially for diagnostic purposes and some internal functions e.g. bad block table creation, the other two modes are for mtd clients: MTD_OOB_PLACE puts/gets the given oob data exactly to/from the place which is described by the ooboffs and ooblen fields of the mtd_oob_ops strcuture. It's up to the caller to make sure that the byte positions are not used by the ECC placement algorithms. MTD_OOB_AUTO puts/gets the given oob data automaticaly to/from the places in the out of band area which are described by the oobfree tuples in the ecclayout data structre which is associated to the devicee. The decision whether data plus oob or oob only handling is done depends on the setting of the datbuf member of the data structure. When datbuf == NULL then the internal read/write_oob functions are selected, otherwise the read/write data routines are invoked. Tested on a few platforms with all variants. Please be aware of possible regressions for your particular device / application scenario Disclaimer: Any whining will be ignored from those who just contributed "hot air blurb" and never sat down to tackle the underlying problem of the mess in the NAND driver grown over time and the big chunk of work to fix up the existing users. The problem was not the holiness of the existing MTD interfaces. The problems was the lack of time to go for the big overhaul. It's easy to add more mess to the existing one, but it takes alot of effort to go for a real solution. Improvements and bugfixes are welcome! Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2006-05-29 03:26:58 +02:00
mtd: fix partition wrapper functions This patch reverts a change that may have been mistakenly included with the set of patches that introduced the new mtd api entry functions. Or perhaps I am mistaken :) The problem is in the partition wrapper functions, where the calls to the driver methods were replaced with calls to the new mtd api functions. This causes the api function to be called a second time, further down the call stack. This is not only unnecessary and redundant - because the sanity checking code and (more restrictive) bounds checks for the partition were done in the first call - but is potentially problematic and confusing. For example, the call stack for a call to mtd_read() on a partitioned device currently looks like this: mtd_read() gets struct mtd_info for the partition | +-> part_read() via the pointer assigned when the partition was created | +->mtd_read() this time gets struct mtd_info for the master | +->xyz_driver_read() via the pointer asigned by the driver It seems that this can cause a variety of problems. For example, if you want to add code to the api function that tests a value in mtd_info that is relevant only to the partition. Or (in my case) you want the driver to return a value that may be different from that returned by the mtd api function. This patch eliminates the second call to the mtd api function. It was tested on the docg4 nand driver with a subset of the api functions, but I inspected the rest and don't see any problems. Signed-off-by: Mike Dunn <mikedunn@newsguy.com> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2012-03-03 13:13:06 -08:00
mtd: fix partition wrapper functions This patch reverts a change that may have been mistakenly included with the set of patches that introduced the new mtd api entry functions. Or perhaps I am mistaken :) The problem is in the partition wrapper functions, where the calls to the driver methods were replaced with calls to the new mtd api functions. This causes the api function to be called a second time, further down the call stack. This is not only unnecessary and redundant - because the sanity checking code and (more restrictive) bounds checks for the partition were done in the first call - but is potentially problematic and confusing. For example, the call stack for a call to mtd_read() on a partitioned device currently looks like this: mtd_read() gets struct mtd_info for the partition | +-> part_read() via the pointer assigned when the partition was created | +->mtd_read() this time gets struct mtd_info for the master | +->xyz_driver_read() via the pointer asigned by the driver It seems that this can cause a variety of problems. For example, if you want to add code to the api function that tests a value in mtd_info that is relevant only to the partition. Or (in my case) you want the driver to return a value that may be different from that returned by the mtd api function. This patch eliminates the second call to the mtd api function. It was tested on the docg4 nand driver with a subset of the api functions, but I inspected the rest and don't see any problems. Signed-off-by: Mike Dunn <mikedunn@newsguy.com> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2012-03-03 13:13:06 -08:00