linux-kernel - Re: [PATCH 4.4 28/40] drm/msm/dsi: Set msm_dsi->encoders before initializing bridge

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Date:   Tue, 7 Nov 2017 10:02:23 +0530
From:   Archit Taneja <architt@...eaurora.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Cc:     stable@...r.kernel.org,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Rob Clark <robdclark@...il.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: Re: [PATCH 4.4 28/40] drm/msm/dsi: Set msm_dsi->encoders before
 initializing bridge

Hi Greg,

On 11/06/2017 03:15 PM, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.

This patch isn't needed on 4.4 or the 4.9 stable branches. This was required
only after drm_bridge API was changed with the commit:

(3bb80f2495) drm: bridge: Link encoder and bridge in core code

This was merged only in 4.11.

Thanks,
Archit

> 
> ------------------
> 
> From: Archit Taneja <architt@...eaurora.org>
> 
> 
> [ Upstream commit 0bb70b82c2f91e4667f3c617505235efd6d77e46 ]
> 
> The commit "drm: bridge: Link encoder and bridge in core code" updated
> the drm_bridge_attach() API to also include the drm_encoder pointer
> the bridge attaches to.
> 
> The func msm_dsi_manager_bridge_init() now relies on the drm_encoder
> pointer stored in msm_dsi->encoders to pass the encoder to the bridge
> API.
> 
> msm_dsi->encoders is unfortunately set after this function is called,
> resulting in us passing a NULL pointer to drm_brigde_attach. This
> results in an error and the DSI driver probe fails.
> 
> Move the initialization of msm_dsi->encoders[] a bit up. Also, don't
> try to set the encoder's bridge. That's now managed by the bridge
> API.
> 
> Cc: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> Signed-off-by: Archit Taneja <architt@...eaurora.org>
> Signed-off-by: Rob Clark <robdclark@...il.com>
> Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> ---
>   drivers/gpu/drm/msm/dsi/dsi.c |    8 +++-----
>   1 file changed, 3 insertions(+), 5 deletions(-)
> 
> --- a/drivers/gpu/drm/msm/dsi/dsi.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi.c
> @@ -205,6 +205,9 @@ int msm_dsi_modeset_init(struct msm_dsi
>   		goto fail;
>   	}
>   
> +	for (i = 0; i < MSM_DSI_ENCODER_NUM; i++)
> +		msm_dsi->encoders[i] = encoders[i];
> +
>   	msm_dsi->bridge = msm_dsi_manager_bridge_init(msm_dsi->id);
>   	if (IS_ERR(msm_dsi->bridge)) {
>   		ret = PTR_ERR(msm_dsi->bridge);
> @@ -213,11 +216,6 @@ int msm_dsi_modeset_init(struct msm_dsi
>   		goto fail;
>   	}
>   
> -	for (i = 0; i < MSM_DSI_ENCODER_NUM; i++) {
> -		encoders[i]->bridge = msm_dsi->bridge;
> -		msm_dsi->encoders[i] = encoders[i];
> -	}
> -
>   	/*
>   	 * check if the dsi encoder output is connected to a panel or an
>   	 * external bridge. We create a connector only if we're connected to a
> 
> 

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