linux-kernel - Re: [PATCH v4 6/7] drm/msm/mdp4: switch LVDS to use drm_bridge/

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Message-ID: <beb866cb-0510-4e8c-84a0-ae66f864303e@quicinc.com>
Date: Fri, 25 Apr 2025 16:01:49 -0700
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        Rob Clark
	<robdclark@...il.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        "Sean
 Paul" <sean@...rly.run>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard
	<mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie
	<airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Rob Herring
	<robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
	<conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio
	<konradybcio@...nel.org>
CC: <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 6/7] drm/msm/mdp4: switch LVDS to use
 drm_bridge/_connector



On 4/25/2025 2:51 AM, Dmitry Baryshkov wrote:
> From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> 
> LVDS support in MDP4 driver makes use of drm_connector directly. However
> LCDC encoder and LVDS connector are wrappers around drm_panel. Switch
> them to use drm_panel_bridge/drm_bridge_connector. This allows using
> standard interface for the drm_panel and also inserting additional
> bridges between encoder and panel.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> ---
>   drivers/gpu/drm/msm/Makefile                       |   1 -
>   drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c           |  34 +++++--
>   drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.h           |   6 +-
>   drivers/gpu/drm/msm/disp/mdp4/mdp4_lcdc_encoder.c  |  20 +----
>   .../gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c    | 100 ---------------------
>   5 files changed, 28 insertions(+), 133 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/Makefile b/drivers/gpu/drm/msm/Makefile
> index 5df20cbeafb8bf07c825a1fd72719d5a56c38613..7a2ada6e2d74a902879e4f12a78ed475e5209ec2 100644
> --- a/drivers/gpu/drm/msm/Makefile
> +++ b/drivers/gpu/drm/msm/Makefile
> @@ -48,7 +48,6 @@ msm-display-$(CONFIG_DRM_MSM_MDP4) += \
>   	disp/mdp4/mdp4_dsi_encoder.o \
>   	disp/mdp4/mdp4_dtv_encoder.o \
>   	disp/mdp4/mdp4_lcdc_encoder.o \
> -	disp/mdp4/mdp4_lvds_connector.o \
>   	disp/mdp4/mdp4_lvds_pll.o \
>   	disp/mdp4/mdp4_irq.o \
>   	disp/mdp4/mdp4_kms.o \
> diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> index 689e210660a5218ed1e2d116073723215af5a187..93c9411eb422bc67b7fedb5ffce4c330310b520f 100644
> --- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> +++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> @@ -6,6 +6,8 @@
>   
>   #include <linux/delay.h>
>   
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_bridge_connector.h>
>   #include <drm/drm_vblank.h>
>   
>   #include "msm_drv.h"
> @@ -189,7 +191,7 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
>   	struct msm_drm_private *priv = dev->dev_private;
>   	struct drm_encoder *encoder;
>   	struct drm_connector *connector;
> -	struct device_node *panel_node;
> +	struct drm_bridge *next_bridge;
>   	int dsi_id;
>   	int ret;
>   
> @@ -199,27 +201,43 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
>   		 * bail out early if there is no panel node (no need to
>   		 * initialize LCDC encoder and LVDS connector)
>   		 */
> -		panel_node = of_graph_get_remote_node(dev->dev->of_node, 0, 0);
> -		if (!panel_node)
> -			return 0;
> +		next_bridge = devm_drm_of_get_bridge(dev->dev, dev->dev->of_node, 0, 0);
> +		if (IS_ERR(next_bridge)) {
> +			ret = PTR_ERR(next_bridge);
> +			if (ret == -ENODEV)
> +				return 0;
> +			return ret;
> +		}

Alright, I think this will protect us against the fact that there is no 
panel in the DT currently like before, hence

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