linux-kernel - Re: [PATCH 11/11] drm/msm/dpu: do not use mixer that supports dspp when not required

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Date:   Thu, 20 Apr 2023 02:18:56 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Arnaud Vrac <avrac@...ebox.fr>, 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>
Cc:     linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 11/11] drm/msm/dpu: do not use mixer that supports dspp
 when not required

On 19/04/2023 17:41, Arnaud Vrac wrote:
> This avoids using lm blocks that support DSPP when not needed, to
> keep those resources available.

This will break some of the platforms. Consider qcm2290 which has a 
single LM with DSPP. So, _dpu_rm_check_lm_and_get_connected_blks should 
be performed in two steps: first skip non-DSPP-enabled LMs when DSPP is 
not required. Then, if the LM (pair) is not found, look for any suitable 
LM(pair).

> 
> Signed-off-by: Arnaud Vrac <avrac@...ebox.fr>
> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> index f4dda88a73f7d..4b393d46c743f 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> @@ -362,7 +362,7 @@ static bool _dpu_rm_check_lm_and_get_connected_blks(struct dpu_rm *rm,
>   	*pp_idx = idx;
>   
>   	if (!reqs->topology.num_dspp)
> -		return true;
> +		return !lm_cfg->dspp;
>   
>   	idx = lm_cfg->dspp - DSPP_0;
>   	if (idx < 0 || idx >= ARRAY_SIZE(rm->dspp_blks)) {
> 

-- 
With best wishes
Dmitry