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93d3fb35aa
The watchdog timer code to recover from the ISP getting stuck has several major issues: 1. There is no way to do fault injection and normally the ISP does not get stuck, so is it is impossible to test it. 2. It in essence just stops all streams, resets the ISP and then brings everything back up. Userspace can easily do this itself by using a timeout on dqbuf and then closing (which causes a poweroff) + re-opening the device. Doing this in userspace (if it ever turns out to be necessary) greatly simplifies the kernel code and in general will be a more robust solution. Even just a quick look at the code finds several more issues: 3. The need to sync-cancel the timers + work on streamoff requires isp->mutex to be dropped halfway during the ioctl opening all sorts of races. 4. The atomisp code supports setting up 2 pipelines, streaming from two sensors at the same time. But there is only a single wdt_work and stopping one of the 2 streams will cancel the timers + work, stopping the wdt even though the other stream might still be running. 5. In case atomisp_css_flush() the sync cancel is done while keeping isp->mutex locked, causing a deadlock when racing with wdt_work which also takes isp->mutex. 6. Even though the watchdog is purely a software/driver thing which just checkes that new frames keep coming in, there are 2 completely different implementations for the ISP2400/ISP2401 which is not necessary at all. So all in all I believe that it is better to just remove the current watchdog implementation. Fixing all the issues with the current implementation will be so much work, that if it turns out that we do need something like this then doing a clean re-implementation from scratch will be better anyways. wdt_work was also (ab)used to reset the ISP after the firmware signalled an fw-assert error through the irq, add a new assert_recover_work to replace this. Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org> |
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| ipc | ||
| kernel | ||
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| virt | ||
| .clang-format | ||
| .cocciconfig | ||
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| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.