Re: [PATCH 1/5] drm/imx-ldb: Add support to drm-bridge

[Philipp Zabel <p.zabel@pengutronix.de>]

Am Montag, den 30.05.2016, 18:39 +0200 schrieb Peter Senna Tschudin:
> Add support to attach a drm_bridge to imx-ldb in addition to
> existing support to attach a LVDS panel.
> 
> Signed-off-by: Peter Senna Tschudin <peter.senna@collabora.com>
> ---
>  drivers/gpu/drm/imx/imx-ldb.c | 75 +++++++++++++++++++++++++++++++------------
>  1 file changed, 54 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/gpu/drm/imx/imx-ldb.c b/drivers/gpu/drm/imx/imx-ldb.c
> index a58eee5..7233a81 100644
> --- a/drivers/gpu/drm/imx/imx-ldb.c
> +++ b/drivers/gpu/drm/imx/imx-ldb.c
> @@ -57,7 +57,11 @@ struct imx_ldb_channel {
>  	struct imx_ldb *ldb;
>  	struct drm_connector connector;
>  	struct drm_encoder encoder;
> +
> +	/* Defines what is connected to the ldb, only one at a time */
>  	struct drm_panel *panel;
> +	struct drm_bridge *ext_bridge;
> +

Just bridge should be clear enough.

>  	struct device_node *child;
>  	int chno;
>  	void *edid;
> @@ -295,6 +299,10 @@ static void imx_ldb_encoder_mode_set(struct drm_encoder *encoder,
>  	}
>  }
>  
> +static void imx_ldb_encoder_enable(struct drm_encoder *encoder)
> +{
> +}
> +

Why?

Note that Liu Ying's atomic series touches this also, and after
"drm/imx: atomic phase 3 step 3: Legacy callback fixups" the enable
callback exists. Depending on how either series proceeds, one will have
to be rebased onto the other.

>  static void imx_ldb_encoder_disable(struct drm_encoder *encoder)
>  {
>  	struct imx_ldb_channel *imx_ldb_ch = enc_to_imx_ldb_ch(encoder);
> @@ -373,6 +381,7 @@ static const struct drm_encoder_helper_funcs imx_ldb_encoder_helper_funcs = {
>  	.prepare = imx_ldb_encoder_prepare,
>  	.commit = imx_ldb_encoder_commit,
>  	.mode_set = imx_ldb_encoder_mode_set,
> +	.enable = imx_ldb_encoder_enable,
>  	.disable = imx_ldb_encoder_disable,
>  };
>  
> @@ -417,16 +426,28 @@ static int imx_ldb_register(struct drm_device *drm,
>  	drm_encoder_init(drm, &imx_ldb_ch->encoder, &imx_ldb_encoder_funcs,
>  			 DRM_MODE_ENCODER_LVDS, NULL);
>  
> -	drm_connector_helper_add(&imx_ldb_ch->connector,
> -			&imx_ldb_connector_helper_funcs);
> -	drm_connector_init(drm, &imx_ldb_ch->connector,
> -			   &imx_ldb_connector_funcs, DRM_MODE_CONNECTOR_LVDS);
> -
> -	if (imx_ldb_ch->panel)
> +	if (imx_ldb_ch->panel) {

	if (!imx_ldb_ch->bridge) {

> +		drm_connector_helper_add(&imx_ldb_ch->connector,
> +				&imx_ldb_connector_helper_funcs);
> +		drm_connector_init(drm, &imx_ldb_ch->connector,
> +				&imx_ldb_connector_funcs,
> +				DRM_MODE_CONNECTOR_LVDS);
>  		drm_panel_attach(imx_ldb_ch->panel, &imx_ldb_ch->connector);
>  
> -	drm_mode_connector_attach_encoder(&imx_ldb_ch->connector,
> -			&imx_ldb_ch->encoder);
> +		drm_mode_connector_attach_encoder(&imx_ldb_ch->connector,
> +				&imx_ldb_ch->encoder);
> +	}
> +
> +	if (imx_ldb_ch->ext_bridge) {
> +		imx_ldb_ch->ext_bridge->encoder = &imx_ldb_ch->encoder;
> +
> +		imx_ldb_ch->encoder.bridge = imx_ldb_ch->ext_bridge;
> +		ret = drm_bridge_attach(drm, imx_ldb_ch->ext_bridge);
> +		if (ret) {
> +			DRM_ERROR("Failed to initialize bridge with drm\n");
> +			return ret;
> +		}
> +	}
>  
>  	return 0;
>  }
> @@ -583,23 +604,35 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
>  			endpoint = of_get_child_by_name(port, "endpoint");
>  			if (endpoint) {
>  				remote = of_graph_get_remote_port_parent(endpoint);
> -				if (remote)
> -					channel->panel = of_drm_find_panel(remote);
> -				else
> -					return -EPROBE_DEFER;
> -				if (!channel->panel) {
> -					dev_err(dev, "panel not found: %s\n",
> -						remote->full_name);

Let's keep this message, at least as dev_dbg.

> -					return -EPROBE_DEFER;
> +				if (remote) {
> +					/* Only one of these two will succeed */
> +					channel->panel =
> +						of_drm_find_panel(remote);
> +
> +					channel->ext_bridge =
> +						of_drm_find_bridge(remote);
> +
> +					/*
> +					 * If the bridge is compiled as a
> +					 * module, it may take some time until
> +					 * the bridge driver is available.
> +					 * Defer until the bridge driver is
> +					 * ready.
> +					 */
> +					if (!channel->panel &&
> +							!channel->ext_bridge)
> +						return -EPROBE_DEFER;
>  				}

What happens if (!remote)?

>  			}
>  		}
>  
> -		edidp = of_get_property(child, "edid", &channel->edid_len);
> -		if (edidp) {
> -			channel->edid = kmemdup(edidp, channel->edid_len,
> -						GFP_KERNEL);
> -		} else if (!channel->panel) {
> +		if (channel->panel) {
> +			edidp = of_get_property(child, "edid",
> +					&channel->edid_len);
> +			if (edidp)
> +				channel->edid = kmemdup(edidp,
> +						channel->edid_len, GFP_KERNEL);
> +		} else {

Any reason to disallow overriding EDID from DT if there is no panel? I'd
leave this part as is.

regards
Philipp