linux-kernel - Re: [PATCH v4 06/16] drm/msm/dpu: fix mixer number counter on allocation

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Message-ID: <lyl74bqxrc46ygtkhawdmmjrfrl3jnxmmkoyjtlhjmghmztqvt@c3zlpfxcz4st>
Date: Thu, 16 Jan 2025 09:54:45 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Jun Nie <jun.nie@...aro.org>
Cc: Rob Clark <robdclark@...il.com>, 
	Abhinav Kumar <quic_abhinavk@...cinc.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 v4 06/16] drm/msm/dpu: fix mixer number counter on
 allocation

On Thu, Jan 16, 2025 at 03:25:55PM +0800, Jun Nie wrote:
> Add the case to reserve multiple pairs mixers for high resolution.
> Current code only supports one pair of mixer usage case. To support
> quad-pipe usage case, two pairs of mixers are needed.
> 
> Reset the current lm_count to an even number instead of completely
> clearing it. This prevents all pairs from being cleared in cases
> where multiple LM pairs are needed.

- The pairs are not being cleared here.
- Problem description before solution.

> 
> Signed-off-by: Jun Nie <jun.nie@...aro.org>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c | 6 +++++-
>  1 file changed, 5 insertions(+), 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 24e085437039e..3b3660d0b166d 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> @@ -321,7 +321,11 @@ static int _dpu_rm_reserve_lms(struct dpu_rm *rm,
>  		if (!rm->mixer_blks[i])
>  			continue;
>  
> -		lm_count = 0;
> +		/*
> +		 * Reset lm_count to an even index. This will drop the previous
> +		 * primary mixer if failed to find its peer.
> +		 */
> +		lm_count &= ~1;
>  		lm_idx[lm_count] = i;
>  
>  		if (!_dpu_rm_check_lm_and_get_connected_blks(rm, global_state,
> 
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry