linux/drivers/i2c
Jean Delvare 1b4dff9cd3 i2c/eeprom: Fall back to SMBus read word transactions
When I2C block reads are not supported by the underlying adapter, use
SMBus read word transactions instead of consecutive byte reads.
Reasons for this change are:

* The consecutive byte read approach is not safe on multi-master buses.

* While consecutive byte reads have less overhead if you only count the
  bytes on the bus, it takes more than twice as many transactions as
  with SMBus read word transactions, and each transaction has a cost:
  taking and releasing the adapter mutex, and for polling drivers,
  waiting for the transaction to complete.

This change yields a significant performance boost at HZ=250 with
EEPROMs on an Intel 82801 bus (basically twice as fast.)

SMBus read word transactions are widely supported so I don't expect
compatibility issues.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
History 2008-07-14 22:38:29 +02:00
..
algos i2c-pca-algo: Fix error code 2008-07-14 22:38:26 +02:00
busses i2c: Let bus drivers add SPD to their class 2008-07-14 22:38:29 +02:00
chips i2c/eeprom: Fall back to SMBus read word transactions 2008-07-14 22:38:29 +02:00
i2c-boardinfo.c i2c: Add i2c_board_info and i2c_new_device() 2007-05-01 23:26:31 +02:00
i2c-core.c i2c: Simplify i2c_del_driver() 2008-07-14 22:38:26 +02:00
i2c-core.h i2c: Add i2c_board_info and i2c_new_device() 2007-05-01 23:26:31 +02:00
i2c-dev.c i2c: Push ioctl BKL down into the i2c code 2008-07-14 22:38:27 +02:00
Kconfig [S390] Kconfig: menus with depends on HAS_IOMEM. 2007-05-10 15:46:07 +02:00
Makefile i2c: Add i2c_board_info and i2c_new_device() 2007-05-01 23:26:31 +02:00