On 2/23/22 17:15, Hans de Goede wrote:
Hi Andy,
On 2/23/22 15:52, Andy Shevchenko wrote:
On Wed, Feb 23, 2022 at 02:48:38PM +0100, Hans de Goede wrote:
Lock the adapter while setting the suspended flag, to ensure that other
locked code always sees the change immediately, rather then possibly using
a stale value.
This involves splitting the suspend/resume callbacks into separate runtime
and normal suspend/resume calls. This is necessary because i2c_dw_xfer()
will get called by the i2c-core with the adapter locked and it in turn
calls the runtime-resume callback through pm_runtime_get_sync().
So the runtime versions of the suspend/resume callbacks cannot take
the adapter-lock. Note this patch simply makes the runtime suspend/resume
callbacks not deal with the suspended flag at all. During runtime the
pm_runtime_get_sync() from i2c_dw_xfer() will always ensure that the
adapter is resumed when necessary.
The suspended flag check is only necessary to check proper suspend/resume
ordering during normal suspend/resume which makes the pm_runtime_get_sync()
call a no-op.
Both patches look good to me and seems like a nice clean up. Not sure if the
first one should be backported (and hence have a Fixes tag).
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Thank you for the review. As for adding a Fixes: tag, this was inspired
by an actual bug-report, but it did not help in fixing the bug, so I left
the fixes tag out.
If you or Wolfram still want to add a Fixes tag, then it should be:
Fixes: 275154155538 ("i2c: designware: Do not allow i2c_dw_xfer() calls while suspended")
Acked-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
