linux-kernel - Re: [PATCH] drm/msm/dpu: filter out too wide modes if no 3dmux is present

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Message-ID: <zae7rlojv5iiq2dx7bxhdsmmzj73o65cwk7kmryxsst36gy2of@k3vcm6omcias>
Date: Sun, 8 Dec 2024 07:29:15 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>
Cc: 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>, linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
	freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/msm/dpu: filter out too wide modes if no 3dmux is
 present

On Fri, Dec 06, 2024 at 12:00:53PM -0800, Abhinav Kumar wrote:
> On chipsets such as QCS615, there is no 3dmux present. In such
> a case, a layer exceeding the max_mixer_width cannot be split,
> hence cannot be supported.
> 
> Filter out the modes which exceed the max_mixer_width when there
> is no 3dmux present. Also, add a check in the dpu_crtc_atomic_check()
> to return failure for such modes.
> 
> Signed-off-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> ---
> Note: this was only compile tested, so its pending validation on QCS615
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> index 9f6ffd344693ecfb633095772a31ada5613345dc..e6e5540aae83be7c20d8ae29115b8fdd42056e55 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> @@ -732,6 +732,13 @@ static int _dpu_crtc_check_and_setup_lm_bounds(struct drm_crtc *crtc,
>  	struct dpu_kms *dpu_kms = _dpu_crtc_get_kms(crtc);
>  	int i;
>  
> +	/* if we cannot merge 2 LMs (no 3d mux) better to fail earlier
> +	 * before even checking the width after the split
> +	 */
> +	if (!dpu_kms->catalog->caps->has_3d_merge
> +	    && adj_mode->hdisplay > dpu_kms->catalog->caps->max_mixer_width)
> +		return -E2BIG;

Is it the same as checking that there are LMs which support
DPU_MIXER_SOURCESPLIT ?

> +
>  	for (i = 0; i < cstate->num_mixers; i++) {
>  		struct drm_rect *r = &cstate->lm_bounds[i];
>  		r->x1 = crtc_split_width * i;
> @@ -1251,6 +1258,12 @@ static enum drm_mode_status dpu_crtc_mode_valid(struct drm_crtc *crtc,
>  {
>  	struct dpu_kms *dpu_kms = _dpu_crtc_get_kms(crtc);
>  
> +	/* if there is no 3d_mux block we cannot merge LMs so we cannot
> +	 * split the large layer into 2 LMs, filter out such modes
> +	 */
> +	if (!dpu_kms->catalog->caps->has_3d_merge
> +	    && mode->hdisplay > dpu_kms->catalog->caps->max_mixer_width)
> +		return MODE_BAD;

This can be more specific, like MODE_BAD_HVALUE.

>  	/*
>  	 * max crtc width is equal to the max mixer width * 2 and max height is 4K
>  	 */
> 
> ---
> base-commit: af2ea8ab7a546b430726183458da0a173d331272
> change-id: 20241206-no_3dmux-521a55ea0669
> 
> Best regards,
> -- 
> Abhinav Kumar <quic_abhinavk@...cinc.com>
> 

-- 
With best wishes
Dmitry