[PATCH] drm/msm/dsi: use RMW cycles in dsi_update_dsc_timing

[Dmitry Baryshkov]

On 30/04/2022 18:16, Abhinav Kumar wrote:
> 
> 
> On 4/30/2022 1:11 AM, Dmitry Baryshkov wrote:
>> The downstream uses read-modify-write for updating command mode
>> compression registers. Let's follow this approach. This also fixes the
>> following warning:
>>
>> drivers/gpu/drm/msm/dsi/dsi_host.c:918:23: warning: variable 
>> 'reg_ctrl' set but not used [-Wunused-but-set-variable]
>>
>> Reported-by: kernel test robot <lkp at intel.com>
>> Fixes: 08802f515c3c ("drm/msm/dsi: Add support for DSC configuration")
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
>> ---
>>   drivers/gpu/drm/msm/dsi/dsi_host.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c 
>> b/drivers/gpu/drm/msm/dsi/dsi_host.c
>> index c983698d1384..a5619ad82a53 100644
>> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
>> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
>> @@ -961,10 +961,12 @@ static void dsi_update_dsc_timing(struct 
>> msm_dsi_host *msm_host, bool is_cmd_mod
>>           reg_ctrl = dsi_read(msm_host, 
>> REG_DSI_COMMAND_COMPRESSION_MODE_CTRL);
>>           reg_ctrl2 = dsi_read(msm_host, 
>> REG_DSI_COMMAND_COMPRESSION_MODE_CTRL2);
>> +        reg_ctrl &= ~0xffff;
>>           reg_ctrl |= reg;
>> +        reg_ctrl &= 
>> ~DSI_COMMAND_COMPRESSION_MODE_CTRL2_STREAM0_SLICE_WIDTH__MASK;
> 
> Shoulnt this be
> 
> reg_ctrl2 &= ~DSI_COMMAND_COMPRESSION_MODE_CTRL2_STREAM0_SLICE_WIDTH__MASK;
> 
> You seem to have used reg_ctrl which is wrong.
> 

Yes. Dummy c&p. I'll post v2 asap.

>>           reg_ctrl2 |= 
>> DSI_COMMAND_COMPRESSION_MODE_CTRL2_STREAM0_SLICE_WIDTH(bytes_in_slice);
>> -        dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL, reg);
>> +        dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL, 
>> reg_ctrl);
>>           dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL2, 
>> reg_ctrl2);
>>       } else {
>>           dsi_write(msm_host, REG_DSI_VIDEO_COMPRESSION_MODE_CTRL, reg);


-- 
With best wishes
Dmitry