regmap: Fixes for v6.4
The most important fix here is for missing dropping of the RCU read lock
when syncing maple tree register caches, the physical devices I have
that use the code don't do any syncing so I'd only ever tested this with
virtual devices and missed the fact that we need to drop the lock in
order to write to buses that need to sleep. Otherwise there's a fix for
an edge case when splitting up large batch writes which has been lurking
for a long time, a check to make sure nobody writes new drivers with a
bug that was found in several SoundWire drivers and a tweak to the way
the new kunit tests are enabled to ensure they don't cause regmap to be
enabled when it wouldn't otherwise be.
regmap: maple: Drop the RCU read lock while syncing registers
Unfortunately the maple tree requires us to explicitly lock it so we need
to take the RCU read lock while iterating. When syncing this means that we
end up trying to write out register values while holding the RCU read lock
which triggers lockdep issues since that is an atomic context but most
buses can't be used in atomic context. Pause the iteration and drop the
lock for each register we check to avoid this.
Reported-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Tested-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230523-regcache-maple-sync-lock-v1-1-530e4d68dfab@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
1 file changed
