linux-kernel - Re: [PATCH v3 05/23] drm/msm/dpu: move resource allocation to CRTC

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Message-ID: <3afded46-7aef-4444-9b61-b97f71d0e5fc@quicinc.com>
Date: Thu, 31 Oct 2024 12:37:03 -0700
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Jessica Zhang <quic_jesszhan@...cinc.com>,
        Rob Clark
	<robdclark@...il.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        "Sean
 Paul" <sean@...rly.run>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        "David Airlie" <airlied@...il.com>,
        Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Simona Vetter <simona@...ll.ch>,
        Simona Vetter <simona.vetter@...ll.ch>
CC: <quic_ebharadw@...cinc.com>, <linux-arm-msm@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>, <freedreno@...ts.freedesktop.org>,
        <linux-kernel@...r.kernel.org>, Rob Clark <robdclark@...omium.org>,
        Ville Syrjälä <ville.syrjala@...ux.intel.com>
Subject: Re: [PATCH v3 05/23] drm/msm/dpu: move resource allocation to CRTC



On 10/16/2024 6:21 PM, Jessica Zhang wrote:
> From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> 
> All resource allocation is centered around the LMs. Then other blocks
> (except DSCs) are allocated basing on the LMs that was selected, and LM
> powers up the CRTC rather than the encoder.
> 
> Moreover if at some point the driver supports encoder cloning,
> allocating resources from the encoder will be incorrect, as all clones
> will have different encoder IDs, while LMs are to be shared by these
> encoders.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> [quic_abhinavk@...cinc.com: Refactored resource allocation for CDM]
> Signed-off-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> [quic_jesszhan@...cinc.com: Changed to grabbing exising global state]
> Signed-off-by: Jessica Zhang <quic_jesszhan@...cinc.com>
> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c    |  86 ++++++++++++
>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 201 +++++++++++-----------------
>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h |  19 +++
>   3 files changed, 183 insertions(+), 123 deletions(-)
> 

<Snip>

> -	/* See dpu_encoder_get_topology, we only support 2:2:1 topology */
> +	/* We only support 2 DSC mode (with 2 LM and 1 INTF) */
>   	if (dpu_enc->dsc)
> -		num_dsc = 2;
> +		topology->num_dsc += 2;
>   
> -	return (num_dsc > 0) && (num_dsc > intf_count);
> -}

I dont recall the context of replacing num_dsc = 2 with num_dsc += 2
and its not documented.

<Snip>

> +	/* We only support 2 DSC mode (with 2 LM and 1 INTF) */
> +	if (dpu_enc->dsc)
> +		num_dsc += 2;
>   
> -	return topology;
> +	return (num_dsc > 0) && (num_dsc > num_intf);
>   }
>   

Same here

This should not break anything with current code. We could land it the 
way it is as this was the version which was last tested and post a 
follow up if this was not right. Something to be documented though, hope 
this note serves that purpose. Rest of the change LGTM,

Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>