linux-kernel - Re: [PATCH 4/4] drm/msm/dpu: Enable compression for command mode

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Message-ID: <714d6e3a-4ddd-bf35-0949-ce162565c000@quicinc.com>
Date:   Wed, 3 May 2023 16:16:09 -0700
From:   Jessica Zhang <quic_jesszhan@...cinc.com>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Marijn Suijten <marijn.suijten@...ainline.org>
CC:     Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] drm/msm/dpu: Enable compression for command mode



On 5/3/2023 12:51 PM, Dmitry Baryshkov wrote:
> On 03/05/2023 22:04, Jessica Zhang wrote:
>>
>>
>> On 5/3/2023 12:28 AM, Marijn Suijten wrote:
>>> On 2023-05-02 18:19:15, Jessica Zhang wrote:
>>>> Add a dpu_hw_intf op to enable data compression.
>>>>
>>>> Signed-off-by: Jessica Zhang <quic_jesszhan@...cinc.com>
>>>> ---
>>>>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c | 4 ++++
>>>>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c          | 7 +++++++
>>>>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h          | 2 ++
>>>>   3 files changed, 13 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c 
>>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>>>> index 74470d068622..4321a1aba17f 100644
>>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>>>
>>> Can we have INTF DCE on video-mode encoders as well?
>>
>> Hi Marijn,
>>
>> Currently, there's no way to validate DSC for video mode as I've only 
>> made changes to support DSI for command mode. We are planning to post 
>> changes to support DSC over DP, which will include changes for video 
>> mode.
> 
> If I remember correctly, HDK8350 panel should support DSC for both 
> command and video modes.

Hi Dmitry,

Correct, however we are planning to submit the video mode changes with 
the DP DSC v1.2 changes.

My current panel driver/dt changes are for command mode, so we would 
have to spent time to also add video mode support. It would be faster to 
land the video mode changes with DP support as that's already a work in 
progress.

> 
>>
>>>
>>>> @@ -72,6 +72,10 @@ static void _dpu_encoder_phys_cmd_update_intf_cfg(
>>>>                   phys_enc->hw_intf,
>>>>                   true,
>>>>                   phys_enc->hw_pp->idx);
>>>> +
>>>> +    if (phys_enc->dpu_kms->catalog->caps->has_data_compress &&
>>>
>>> As per my suggestion on patch 3/4, drop the flag and check above and
>>> only check if the function is NULL (below).
>>
>> Acked.
>>
>>>
>>>> +            phys_enc->hw_intf->ops.enable_compression)
>>>> +        phys_enc->hw_intf->ops.enable_compression(phys_enc->hw_intf);
>>>>   }
>>>>   static void dpu_encoder_phys_cmd_pp_tx_done_irq(void *arg, int 
>>>> irq_idx)
>>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c 
>>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
>>>> index 671048a78801..4ce7ffdd7a05 100644
>>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
>>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
>>>> @@ -64,10 +64,16 @@
>>>>   #define INTF_CFG2_DATABUS_WIDEN    BIT(0)
>>>>   #define INTF_CFG2_DATA_HCTL_EN    BIT(4)
>>>
>>> These should probably be reindented to match the below... And the rest
>>> of the defines use spaces instead of tabs.
>>
>> Fair point, though I think fixing the whitespace for these 2 macros 
>> specifically might be better in a more relevant series.
>>
>> With that being said, I'll change the spacing of the DATA_COMPRESS bit 
>> to spaces instead of tabs.
>>
>>>
>>>> +#define INTF_CFG2_DCE_DATA_COMPRESS    BIT(12)
>>>>   #define INTF_MISR_CTRL            0x180
>>>>   #define INTF_MISR_SIGNATURE        0x184
>>>
>>> This does not seem to apply on top of:
>>> https://lore.kernel.org/linux-arm-msm/20230411-dpu-intf-te-v4-10-27ce1a5ab5c6@somainline.org/
>>
>> Seems like I'm missing some patches from that series on my working 
>> branch. Will rebase on top of the full series for the v2.
>>
>>>
>>>> +static inline void dpu_hw_intf_enable_compression(struct 
>>>> dpu_hw_intf *ctx)
>>>
>>> Why inline?  This is used as a pointer callback.
>>
>> Acked, will remove the inline.
>>
>>>
>>>> +{
>>>> +    DPU_REG_WRITE(&ctx->hw, INTF_CONFIG2, 
>>>> INTF_CFG2_DCE_DATA_COMPRESS);
>>>
>>> dpu_hw_intf_setup_timing_engine() also programs INTF_CONFIG2.  Is it
>>> double-buffered, or is that config **always** unused when DSI CMD mode
>>> is used in conjunction with DSC/DCE?  Otherwise this should perhaps OR
>>> the bitflag into the register, or write the whole thing at once in
>>> dpu_hw_intf_setup_timing_engine()?
>>
>> For command mode, INTF_CONFIG2 is unused aside from setting 
>> DATA_COMPRESS for DSC.
>>
>> Since setup_timing_engine() is only used for video mode, the 
>> corresponding changes will be made in the DSC v1.2 for DP changes.
> 
> So, for command mode panels is this the only bit that should be set in 
> INTF_CFG2?

Yep, outside of the changes in this patch, INTF_CONFIG2 is only used in 
the video mode setup_timing_engine() method.

Thanks,

Jessica Zhang

> -- 
> With best wishes
> Dmitry
>