linux-kernel - Re: [PATCH v2 1/3] drm/msm/dsi: Support NO

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Date:   Fri, 1 Oct 2021 20:28:28 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Rob Clark <robdclark@...il.com>, dri-devel@...ts.freedesktop.org
Cc:     freedreno@...ts.freedesktop.org,
        Douglas Anderson <dianders@...omium.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Rob Clark <robdclark@...omium.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Abhinav Kumar <abhinavk@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <linux-arm-msm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] drm/msm/dsi: Support NO_CONNECTOR bridges

On 21/09/2021 01:57, Rob Clark wrote:
> From: Rob Clark <robdclark@...omium.org>
> 
> For now, since we have a mix of bridges which support this flag, which
> which do *not* support this flag, or work both ways, try it once with
> NO_CONNECTOR and then fall back to the old way if that doesn't work.
> Eventually we can drop the fallback path.
> 
> v2: Add missing drm_connector_attach_encoder() so display actually comes
>      up when the bridge properly handles the NO_CONNECTOR flag
> 
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

I think this patch can go through the drm/msm, while two other patches 
would need to through the drm-misc. Is it correct?

> ---
>   drivers/gpu/drm/msm/Kconfig           |  2 ++
>   drivers/gpu/drm/msm/dsi/dsi_manager.c | 50 ++++++++++++++++++++-------
>   2 files changed, 39 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/Kconfig b/drivers/gpu/drm/msm/Kconfig
> index e9c6af78b1d7..36e5ba3ccc28 100644
> --- a/drivers/gpu/drm/msm/Kconfig
> +++ b/drivers/gpu/drm/msm/Kconfig
> @@ -14,6 +14,8 @@ config DRM_MSM
>   	select REGULATOR
>   	select DRM_KMS_HELPER
>   	select DRM_PANEL
> +	select DRM_BRIDGE
> +	select DRM_PANEL_BRIDGE
>   	select DRM_SCHED
>   	select SHMEM
>   	select TMPFS
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_manager.c b/drivers/gpu/drm/msm/dsi/dsi_manager.c
> index c41d39f5b7cf..e25877073d31 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_manager.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_manager.c
> @@ -3,6 +3,8 @@
>    * Copyright (c) 2015, The Linux Foundation. All rights reserved.
>    */
>   
> +#include "drm/drm_bridge_connector.h"
> +
>   #include "msm_kms.h"
>   #include "dsi.h"
>   
> @@ -688,10 +690,10 @@ struct drm_connector *msm_dsi_manager_ext_bridge_init(u8 id)
>   {
>   	struct msm_dsi *msm_dsi = dsi_mgr_get_dsi(id);
>   	struct drm_device *dev = msm_dsi->dev;
> +	struct drm_connector *connector;
>   	struct drm_encoder *encoder;
>   	struct drm_bridge *int_bridge, *ext_bridge;
> -	struct drm_connector *connector;
> -	struct list_head *connector_list;
> +	int ret;
>   
>   	int_bridge = msm_dsi->bridge;
>   	ext_bridge = msm_dsi->external_bridge =
> @@ -699,22 +701,44 @@ struct drm_connector *msm_dsi_manager_ext_bridge_init(u8 id)
>   
>   	encoder = msm_dsi->encoder;
>   
> -	/* link the internal dsi bridge to the external bridge */
> -	drm_bridge_attach(encoder, ext_bridge, int_bridge, 0);
> -
>   	/*
> -	 * we need the drm_connector created by the external bridge
> -	 * driver (or someone else) to feed it to our driver's
> -	 * priv->connector[] list, mainly for msm_fbdev_init()
> +	 * Try first to create the bridge without it creating its own
> +	 * connector.. currently some bridges support this, and others
> +	 * do not (and some support both modes)
>   	 */
> -	connector_list = &dev->mode_config.connector_list;
> +	ret = drm_bridge_attach(encoder, ext_bridge, int_bridge,
> +			DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> +	if (ret == -EINVAL) {
> +		struct drm_connector *connector;
> +		struct list_head *connector_list;
> +
> +		/* link the internal dsi bridge to the external bridge */
> +		drm_bridge_attach(encoder, ext_bridge, int_bridge, 0);
> +
> +		/*
> +		 * we need the drm_connector created by the external bridge
> +		 * driver (or someone else) to feed it to our driver's
> +		 * priv->connector[] list, mainly for msm_fbdev_init()
> +		 */
> +		connector_list = &dev->mode_config.connector_list;
>   
> -	list_for_each_entry(connector, connector_list, head) {
> -		if (drm_connector_has_possible_encoder(connector, encoder))
> -			return connector;
> +		list_for_each_entry(connector, connector_list, head) {
> +			if (drm_connector_has_possible_encoder(connector, encoder))
> +				return connector;
> +		}
> +
> +		return ERR_PTR(-ENODEV);
> +	}
> +
> +	connector = drm_bridge_connector_init(dev, encoder);
> +	if (IS_ERR(connector)) {
> +		DRM_ERROR("Unable to create bridge connector\n");
> +		return ERR_CAST(connector);
>   	}
>   
> -	return ERR_PTR(-ENODEV);
> +	drm_connector_attach_encoder(connector, encoder);
> +
> +	return connector;
>   }
>   
>   void msm_dsi_manager_bridge_destroy(struct drm_bridge *bridge)
> 


-- 
With best wishes
Dmitry