Re: [PATCH RFC 3/5] drm/msm/dpu: Use DRM DSC helper for det_thresh_flatness

[Jessica Zhang <quic_jesszhan@quicinc.com>]

On 3/29/2023 4:31 PM, Dmitry Baryshkov wrote:
> On 30/03/2023 02:18, Jessica Zhang wrote:
>> Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
>> ---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c 
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c
>> index 619926da1441..648c530b5d05 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c
>> @@ -3,6 +3,8 @@
>>    * Copyright (c) 2020-2022, Linaro Limited
>>    */
>> +#include <drm/display/drm_dsc_helper.h>
>> +
>>   #include "dpu_kms.h"
>>   #include "dpu_hw_catalog.h"
>>   #include "dpu_hwio.h"
>> @@ -102,7 +104,7 @@ static void dpu_hw_dsc_config(struct dpu_hw_dsc 
>> *hw_dsc,
>>       data |= dsc->final_offset;
>>       DPU_REG_WRITE(c, DSC_DSC_OFFSET, data);
>> -    det_thresh_flatness = 7 + 2 * (dsc->bits_per_component - 8);
>> +    det_thresh_flatness = drm_dsc_calculate_det_thresh_flatness(dsc);
> 
> But this changes the value! Compare:
> 
> bpc | old | new
> 8   | 7   | 2
> 10  | 11  | 8
> 12  | 15  | 256
> 
> If this is intentional, please state so and maybe add a Fixes tag.

Hi Dmitry,

Yep this was intentional to match downstream and the spec. Will add a 
fixes tag for this.

Thanks,

Jessica Zhang

> 
> 
>>       data = det_thresh_flatness << 10;
>>       data |= dsc->flatness_max_qp << 5;
>>       data |= dsc->flatness_min_qp;
>>
> 
> -- 
> With best wishes
> Dmitry
>