linux-kernel - Re: [PATCH 18/35] drm/msm/dpu: get rid of DPU_PINGPONG

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Message-ID: <1b429f3f-2fff-45bb-86dd-48b1d164ccc8@quicinc.com>
Date: Thu, 23 Jan 2025 13:32:02 -0800
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Rob Clark
	<robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Marijn Suijten
	<marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona
 Vetter <simona@...ll.ch>,
        Vinod Koul <vkoul@...nel.org>, Konrad Dybcio
	<konradybcio@...nel.org>
CC: <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 18/35] drm/msm/dpu: get rid of DPU_PINGPONG_DSC



On 12/13/2024 2:14 PM, Dmitry Baryshkov wrote:
> Continue migration to the MDSS-revision based checks and replace
> DPU_PINGPONG_DSC feature bit with the core_major_ver < 7 check.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> ---
>   drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_1_14_msm8937.h |  2 --
>   drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_1_15_msm8917.h |  1 -
>   drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_1_16_msm8953.h |  2 --
>   drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_1_7_msm8996.h  |  6 ++----
>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c           | 10 ++--------
>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h           |  2 --
>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c          |  2 +-
>   7 files changed, 5 insertions(+), 20 deletions(-)
> 

<snip>

> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c
> index 36c0ec775b92036eaab26e1fa5331579651ac27c..49e03ecee9e8b567a3f809b977deb83731006ac0 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c
> @@ -319,7 +319,7 @@ struct dpu_hw_pingpong *dpu_hw_pingpong_init(struct drm_device *dev,
>   		c->ops.disable_autorefresh = dpu_hw_pp_disable_autorefresh;
>   	}
>   
> -	if (test_bit(DPU_PINGPONG_DSC, &cfg->features)) {
> +	if (mdss_rev->core_major_ver < 7) {
>   		c->ops.setup_dsc = dpu_hw_pp_setup_dsc;
>   		c->ops.enable_dsc = dpu_hw_pp_dsc_enable;
>   		c->ops.disable_dsc = dpu_hw_pp_dsc_disable;
> 

So far in this series, we replaced the feature bits with >= checks of 
core_revisions. That kind of works as usually feature bits get added 
after a specific version.

With this patch and later, whenever we use < checks it gets a bit tricky 
as we might also need an upper bound. Feature bits gave individual 
control of chipsets but generalizing that all chipsets < 7 have PP DSC 
is also not correct. I have to really cross-check but there could be 
some old chipsets which do not have DSC at all.