linux-kernel - Re: [PATCH v8 6/8] drm/msm/dpu: separate DSC flush update out of interface

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Message-ID: <411b27d1-6c1d-fa7e-111a-ab8f02ab3981@quicinc.com>
Date:   Fri, 12 May 2023 12:05:32 -0700
From:   Abhinav Kumar <quic_abhinavk@...cinc.com>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Kuogee Hsieh <quic_khsieh@...cinc.com>,
        <dri-devel@...ts.freedesktop.org>, <robdclark@...il.com>,
        <sean@...rly.run>, <swboyd@...omium.org>, <dianders@...omium.org>,
        <vkoul@...nel.org>, <daniel@...ll.ch>, <airlied@...il.com>,
        <agross@...nel.org>, <andersson@...nel.org>
CC:     <quic_sbillaka@...cinc.com>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <marijn.suijten@...ainline.org>,
        <quic_jesszhan@...cinc.com>, <freedreno@...ts.freedesktop.org>
Subject: Re: [PATCH v8 6/8] drm/msm/dpu: separate DSC flush update out of
 interface



On 5/12/2023 11:50 AM, Dmitry Baryshkov wrote:
> On 12/05/2023 21:47, Abhinav Kumar wrote:
>>
>>
>> On 5/12/2023 11:21 AM, Dmitry Baryshkov wrote:
>>> On 12/05/2023 21:00, Kuogee Hsieh wrote:
>>>> Current DSC flush update is piggyback inside dpu_hw_ctl_intf_cfg_v1().
>>>> This patch separates DSC flush away from dpu_hw_ctl_intf_cfg_v1() by
>>>> adding dpu_hw_ctl_update_pending_flush_dsc_v1() to handle both per
>>>> DSC engine and DSC flush bits at same time to make it consistent with
>>>> the location of flush programming of other dpu sub blocks.
>>>>
>>>> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
>>>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
>>>> ---
>>>>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 14 ++++++++++++--
>>>>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c  | 22 
>>>> ++++++++++++++++------
>>>>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.h  | 10 ++++++++++
>>>>   3 files changed, 38 insertions(+), 8 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c 
>>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>>> index ffa6f04..5cae70e 100644
>>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>>> @@ -1834,12 +1834,18 @@ dpu_encoder_dsc_initial_line_calc(struct 
>>>> drm_dsc_config *dsc,
>>>>       return DIV_ROUND_UP(total_pixels, dsc->slice_width);
>>>>   }
>>>> -static void dpu_encoder_dsc_pipe_cfg(struct dpu_hw_dsc *hw_dsc,
>>>> +static void dpu_encoder_dsc_pipe_cfg(struct dpu_encoder_virt *dpu_enc,
>>>> +                     struct dpu_hw_dsc *hw_dsc,
>>>>                        struct dpu_hw_pingpong *hw_pp,
>>>>                        struct drm_dsc_config *dsc,
>>>>                        u32 common_mode,
>>>>                        u32 initial_lines)
>>>>   {
>>>> +    struct dpu_encoder_phys *cur_master = dpu_enc->cur_master;
>>>> +    struct dpu_hw_ctl *ctl;
>>>> +
>>>> +    ctl = cur_master->hw_ctl;
>>>
>>> Just for my understanding: if we have a bonded DSI @ sdm845, should 
>>> both flashes go to the master CTL or each flush should go to the 
>>> corresponding CTL?
>>>
>>
>> Is this question for DSC or just general question about flush?
>>
>> I dont see an explicit DSC flush needed in sdm845 at the ctl level.
>>
>> If the question is about general flush involving two control paths, we 
>> need to combine the flushes and they goto the master only. Please 
>> refer to below part in sde_encoder.c
> And this is because we have a single CTL to flush on sm8150+, isn't it?
> 

For sm8150+, yes there will be only a single CTL to flush even in bonded 
DSI mode so only one will be flushed.

So, in general, you can refer to the function 
sde_encoder_phys_needs_single_flush() to decide if it needs 2 flushes or 
one. That accounts for the DPU rev as well.

>>
>> 4243     /* for split flush, combine pending flush masks and send to 
>> master */
>> 4244     if (pending_flush.pending_flush_mask && sde_enc->cur_master) {
>> 4245         ctl = sde_enc->cur_master->hw_ctl;
>> 4246         if (config_changed && ctl->ops.reg_dma_flush)
>> 4247             ctl->ops.reg_dma_flush(ctl, is_regdma_blocking);
>> 4248         _sde_encoder_trigger_flush(&sde_enc->base, 
>> sde_enc->cur_master,
>> 4249                         &pending_flush,
>> 4250                         config_changed);
>> 4251     }
> 
>