soundwire: intel: read AC timing control register before updating it
authorChao Song <chao.song@linux.intel.com>
Mon, 15 May 2023 08:13:01 +0000 (16:13 +0800)
committerVinod Koul <vkoul@kernel.org>
Sat, 27 May 2023 10:38:48 +0000 (16:08 +0530)
commit3d912d1a28da59a95e046feff3ea2bc38e00138e
tree5570298242bc4ecae942cf32b9d7e327ff08d402
parent6dd0776ddde8ae187c04803c53becd55eccf4fc3
soundwire: intel: read AC timing control register before updating it

Start from ACE1.x, DOAISE is added to AC timing control
register bit 5, it combines with DOAIS to get effective
timing, and has the default value 1.

The current code fills DOAIS, DACTQE and DODS bits to a
variable initialized to zero, and updates the variable
to AC timing control register. With this operation, We
change DOAISE to 0, and force a much more aggressive
timing. The timing is even unable to form a working
waveform on SDA pin on Meteorlake.

This patch uses read-modify-write operation for the AC
timing control register access, thus makes sure those
bits not supposed and intended to change are not touched.

Signed-off-by: Chao Song <chao.song@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20230515081301.12921-1-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
drivers/soundwire/intel.c