Re: [PATCH v6 1/8] drm/msm/dp: Add eDP support via aux_bus

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 30/03/2022 19:02, Sankeerth Billakanti wrote:
> This patch adds support for generic eDP sink through aux_bus. The eDP/DP
> controller driver should support aux transactions originating from the
> panel-edp driver and hence should be initialized and ready.
> 
> The panel bridge supporting the panel should be ready before the bridge
> connector is initialized. The generic panel probe needs the controller
> resources to be enabled to support the aux transactions originating from
> the panel probe.
> 
> Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com>
> ---
> 
> Changes in v6:
>    - Remove initialization
>    - Fix aux_bus node leak
>    - Split the patches
> 
>   drivers/gpu/drm/msm/dp/dp_display.c | 54 +++++++++++++++++++++++++++++++++++--
>   drivers/gpu/drm/msm/dp/dp_drm.c     | 10 ++++---
>   drivers/gpu/drm/msm/dp/dp_parser.c  | 21 +--------------
>   drivers/gpu/drm/msm/dp/dp_parser.h  |  1 +
>   4 files changed, 60 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 382b3aa..e082d02 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -10,6 +10,7 @@
>   #include <linux/component.h>
>   #include <linux/of_irq.h>
>   #include <linux/delay.h>
> +#include <drm/dp/drm_dp_aux_bus.h>
>   
>   #include "msm_drv.h"
>   #include "msm_kms.h"
> @@ -265,8 +266,6 @@ static int dp_display_bind(struct device *dev, struct device *master,
>   		goto end;
>   	}
>   
> -	dp->dp_display.next_bridge = dp->parser->next_bridge;
> -
>   	dp->aux->drm_dev = drm;
>   	rc = dp_aux_register(dp->aux);
>   	if (rc) {
> @@ -1524,6 +1523,53 @@ void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor)
>   	}
>   }
>   
> +static int dp_display_get_next_bridge(struct msm_dp *dp)
> +{
> +	int rc;
> +	struct dp_display_private *dp_priv;
> +	struct device_node *aux_bus;
> +	struct device *dev;
> +
> +	dp_priv = container_of(dp, struct dp_display_private, dp_display);
> +	dev = &dp_priv->pdev->dev;
> +	aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
> +
> +	if (aux_bus) {
> +		dp_display_host_init(dp_priv);
> +		dp_catalog_ctrl_hpd_config(dp_priv->catalog);
> +		enable_irq(dp_priv->irq);
> +		dp_display_host_phy_init(dp_priv);
> +
> +		devm_of_dp_aux_populate_ep_devices(dp_priv->aux);
> +
> +		disable_irq(dp_priv->irq);
> +		of_node_put(aux_bus);
> +	}
> +
> +	/*
> +	 * External bridges are mandatory for eDP interfaces: one has to
> +	 * provide at least an eDP panel (which gets wrapped into panel-bridge).
> +	 *
> +	 * For DisplayPort interfaces external bridges are optional, so
> +	 * silently ignore an error if one is not present (-ENODEV).
> +	 */
> +	rc = dp_parser_find_next_bridge(dp_priv->parser);
> +	if (rc == -ENODEV) {
> +		if (dp->connector_type == DRM_MODE_CONNECTOR_eDP) {

The more I think about these conditions, the closer I dislike them (yes, 
I added this one in one of the patches). I'd suggest to change 
dp->connector_type to boolean 'is_edp' field use it in all conditions 
instead.

> +			DRM_ERROR("eDP: next bridge is not present\n");
> +			return rc;
> +		}
> +	} else if (rc) {
> +		if (rc != -EPROBE_DEFER)
> +			DRM_ERROR("DP: error parsing next bridge: %d\n", rc);
> +		return rc;
> +	}
> +
> +	dp->next_bridge = dp_priv->parser->next_bridge;
> +
> +	return 0;
> +}
> +
>   int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev,
>   			struct drm_encoder *encoder)
>   {
> @@ -1547,6 +1593,10 @@ int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev,
>   
>   	dp_display->encoder = encoder;
>   
> +	ret = dp_display_get_next_bridge(dp_display);
> +	if (ret)
> +		return ret;
> +
>   	dp_display->bridge = dp_bridge_init(dp_display, dev, encoder);
>   	if (IS_ERR(dp_display->bridge)) {
>   		ret = PTR_ERR(dp_display->bridge);
> diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
> index 7ce1aca..5254bd6 100644
> --- a/drivers/gpu/drm/msm/dp/dp_drm.c
> +++ b/drivers/gpu/drm/msm/dp/dp_drm.c
> @@ -114,10 +114,12 @@ struct drm_bridge *dp_bridge_init(struct msm_dp *dp_display, struct drm_device *
>   	bridge->funcs = &dp_bridge_ops;
>   	bridge->type = dp_display->connector_type;
>   
> -	bridge->ops =
> -		DRM_BRIDGE_OP_DETECT |
> -		DRM_BRIDGE_OP_HPD |
> -		DRM_BRIDGE_OP_MODES;
> +	if (bridge->type == DRM_MODE_CONNECTOR_DisplayPort) {

And in this case we can also check dp_display->connector_type (or the 
suggested dp_display->is_edp) for the uniformity of the code.

> +		bridge->ops =
> +			DRM_BRIDGE_OP_DETECT |
> +			DRM_BRIDGE_OP_HPD |
> +			DRM_BRIDGE_OP_MODES;

I think OP_MODES should be used for eDP, shouldn't it?

> +	}
>   
>   	rc = drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
>   	if (rc) {
> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c b/drivers/gpu/drm/msm/dp/dp_parser.c
> index 1056b8d..6317dce 100644
> --- a/drivers/gpu/drm/msm/dp/dp_parser.c
> +++ b/drivers/gpu/drm/msm/dp/dp_parser.c
> @@ -265,7 +265,7 @@ static int dp_parser_clock(struct dp_parser *parser)
>   	return 0;
>   }
>   
> -static int dp_parser_find_next_bridge(struct dp_parser *parser)
> +int dp_parser_find_next_bridge(struct dp_parser *parser)
>   {
>   	struct device *dev = &parser->pdev->dev;
>   	struct drm_bridge *bridge;
> @@ -300,25 +300,6 @@ static int dp_parser_parse(struct dp_parser *parser, int connector_type)
>   	if (rc)
>   		return rc;
>   
> -	/*
> -	 * External bridges are mandatory for eDP interfaces: one has to
> -	 * provide at least an eDP panel (which gets wrapped into panel-bridge).
> -	 *
> -	 * For DisplayPort interfaces external bridges are optional, so
> -	 * silently ignore an error if one is not present (-ENODEV).
> -	 */
> -	rc = dp_parser_find_next_bridge(parser);
> -	if (rc == -ENODEV) {
> -		if (connector_type == DRM_MODE_CONNECTOR_eDP) {
> -			DRM_ERROR("eDP: next bridge is not present\n");
> -			return rc;
> -		}
> -	} else if (rc) {
> -		if (rc != -EPROBE_DEFER)
> -			DRM_ERROR("DP: error parsing next bridge: %d\n", rc);
> -		return rc;
> -	}
> -
>   	/* Map the corresponding regulator information according to
>   	 * version. Currently, since we only have one supported platform,
>   	 * mapping the regulator directly.
> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.h b/drivers/gpu/drm/msm/dp/dp_parser.h
> index d371bae..091ff41 100644
> --- a/drivers/gpu/drm/msm/dp/dp_parser.h
> +++ b/drivers/gpu/drm/msm/dp/dp_parser.h
> @@ -140,5 +140,6 @@ struct dp_parser {
>    * can be parsed using this module.
>    */
>   struct dp_parser *dp_parser_get(struct platform_device *pdev);
> +int dp_parser_find_next_bridge(struct dp_parser *parser);
>   
>   #endif


-- 
With best wishes
Dmitry