linux-kernel - Re: [PATCH v2 09/11] drm/msm/disp/dpu1: Add support for DSC in topology

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Date:   Mon, 25 Oct 2021 17:37:30 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Vinod Koul <vkoul@...nel.org>, Rob Clark <robdclark@...il.com>
Cc:     linux-arm-msm@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Jonathan Marek <jonathan@...ek.ca>,
        Abhinav Kumar <abhinavk@...eaurora.org>,
        Jeffrey Hugo <jeffrey.l.hugo@...il.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org
Subject: Re: [PATCH v2 09/11] drm/msm/disp/dpu1: Add support for DSC in
 topology

On 14/10/2021 17:13, Dmitry Baryshkov wrote:
> On 07/10/2021 10:08, Vinod Koul wrote:
>> For DSC to work we typically need a 2,2,1 configuration. This should
>> suffice for resolutions upto 4k. For more resolutions like 8k this won't
>> work.
>>
>> Also, it is better to use 2 LMs and DSC instances as half width results
>> in lesser power consumption as compared to single LM, DSC at full width.
>>
>> The panel has been tested only with 2,2,1 configuration, so for
>> now we blindly create 2,2,1 topology when DSC is enabled
>>
>> Co-developed-by: Abhinav Kumar <abhinavk@...eaurora.org>
>> Signed-off-by: Abhinav Kumar <abhinavk@...eaurora.org>
>> Signed-off-by: Vinod Koul <vkoul@...nel.org>
>> ---
>> Changes since
>> RFC:
>>   - Add more details in changelog
>>
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 16 ++++++++++++++++
>>   1 file changed, 16 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c 
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> index aac51c1bdf94..70f57a071165 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> @@ -538,6 +538,8 @@ static struct msm_display_topology 
>> dpu_encoder_get_topology(
>>               struct drm_display_mode *mode)
>>   {
>>       struct msm_display_topology topology = {0};
>> +    struct drm_encoder *drm_enc;
>> +    struct msm_drm_private *priv;
>>       int i, intf_count = 0;
>>       for (i = 0; i < MAX_PHYS_ENCODERS_PER_VIRTUAL; i++)
>> @@ -572,8 +574,22 @@ static struct msm_display_topology 
>> dpu_encoder_get_topology(
>>       topology.num_enc = 0;
>>       topology.num_intf = intf_count;
>> +    drm_enc = &dpu_enc->base;
>> +    priv = drm_enc->dev->dev_private;
>> +    if (priv && priv->dsc) {
>> +        /* In case of Display Stream Compression DSC, we would use
>> +         * 2 encoders, 2 line mixers and 1 interface
>> +         * this is power optimal and can drive upto (including) 4k
>> +         * screens
>> +         */
>> +        topology.num_enc = 2;
>> +        topology.num_intf = 1;
>> +        topology.num_lm = 2;
> 
> So, here you'd set the topology.num_rm.

I meant 'num_dsc', please excuse the typo.

> 
>> +    }
>> +
>>       return topology;
>>   }
>> +
>>   static int dpu_encoder_virt_atomic_check(
>>           struct drm_encoder *drm_enc,
>>           struct drm_crtc_state *crtc_state,
>>
> 
> 


-- 
With best wishes
Dmitry