85e654c9f7
It's possible for interrupts to get significantly delayed to the point
that callers of intel_scu_ipc_dev_command() and friends can call the
function once, hit a timeout, and call it again while the interrupt
still hasn't been processed. This driver will get seriously confused if
the interrupt is finally processed after the second IPC has been sent
with ipc_command(). It won't know which IPC has been completed. This
could be quite disastrous if calling code assumes something has happened
upon return from intel_scu_ipc_dev_simple_command() when it actually
hasn't.
Let's avoid this scenario by simply returning -EBUSY in this case.
Hopefully higher layers will know to back off or fail gracefully when
this happens. It's all highly unlikely anyway, but it's better to be
correct here as we have no way to know which IPC the status register is
telling us about if we send a second IPC while the previous IPC is still
processing.
Cc: Prashant Malani <pmalani@chromium.org>
Cc: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Fixes: ed12f295bfd5 ("ipc: Added support for IPC interrupt mode")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20230913212723.3055315-5-swboyd@chromium.org
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
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.