linux-kernel - Re: [PATCH] drm/lcdif: switch to DRM_BRIDGE_ATTACH_NO

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Date: Mon, 24 Jun 2024 13:32:20 +0200
From: Alexander Stein <alexander.stein@...tq-group.com>
To: Marek Vasut <marex@...x.de>, Stefan Agner <stefan@...er.ch>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>, Fabio Estevam <festevam@...il.com>, Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: dri-devel@...ts.freedesktop.org, imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Subject: Re: [PATCH] drm/lcdif: switch to DRM_BRIDGE_ATTACH_NO_CONNECTOR

Hi,

Am Montag, 24. Juni 2024, 12:31:46 CEST schrieb Dmitry Baryshkov:
> Existing in-kernel device trees use LCDIF with the dsim + adv7533, dsim
> + tc358762 or with ldb + panel_bridge. All these combinations support
> using DRM_BRIDGE_ATTACH_NO_CONNECTOR for bridge attachment.
> 
> Change lcdif driver to use this flag when attaching the bridge and
> create drm_bridge_connector afterwards.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> ---
> Note: compile-tested only.

I gave it a try, but it doesn't work. Despite DSI output it also breaks
HDMI output, where I at least some error messages:
[drm:drm_bridge_attach] *ERROR* failed to attach bridge /soc@...us@...00000/hdmi@...d8000 to encoder None-37: -22
[drm:drm_bridge_attach] *ERROR* failed to attach bridge /soc@...us@...00000/display-bridge@...c4000 to encoder None-37: -22
imx-lcdif 32fc6000.display-controller: error -EINVAL: Failed to attach bridge for endpoint0
imx-lcdif 32fc6000.display-controller: error -EINVAL: Cannot connect bridge
imx-lcdif 32fc6000.display-controller: probe with driver imx-lcdif failed with error -22

Best regards,
Alexander

> ---
>  drivers/gpu/drm/mxsfb/lcdif_drv.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mxsfb/lcdif_drv.c b/drivers/gpu/drm/mxsfb/lcdif_drv.c
> index 0f895b8a99d6..1d5508449995 100644
> --- a/drivers/gpu/drm/mxsfb/lcdif_drv.c
> +++ b/drivers/gpu/drm/mxsfb/lcdif_drv.c
> @@ -16,6 +16,7 @@
>  
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_bridge.h>
> +#include <drm/drm_bridge_connector.h>
>  #include <drm/drm_drv.h>
>  #include <drm/drm_encoder.h>
>  #include <drm/drm_fbdev_dma.h>
> @@ -48,6 +49,7 @@ static int lcdif_attach_bridge(struct lcdif_drm_private *lcdif)
>  {
>  	struct device *dev = lcdif->drm->dev;
>  	struct device_node *ep;
> +	struct drm_connector *connector;
>  	struct drm_bridge *bridge;
>  	int ret;
>  
> @@ -96,13 +98,23 @@ static int lcdif_attach_bridge(struct lcdif_drm_private *lcdif)
>  			return ret;
>  		}
>  
> -		ret = drm_bridge_attach(encoder, bridge, NULL, 0);
> +		ret = drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
>  		if (ret) {
>  			of_node_put(ep);
>  			return dev_err_probe(dev, ret,
>  					     "Failed to attach bridge for endpoint%u\n",
>  					     of_ep.id);
>  		}
> +
> +		connector = drm_bridge_connector_init(lcdif->drm, encoder);
> +		if (IS_ERR(connector)) {
> +			ret = PTR_ERR(connector);
> +			of_node_put(ep);
> +
> +			return dev_err_probe(dev, ret,
> +					     "Failed to create bridge connector for endpoint%u\n",
> +					     of_ep.id);
> +		}
>  	}
>  
>  	return 0;
> 
> ---
> base-commit: f76698bd9a8ca01d3581236082d786e9a6b72bb7
> change-id: 20240624-mxc-lcdif-bridge-attach-60368807b2f9
> 
> Best regards,
> 


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