Re: [PATCH v2 3/3] drm/bridge: ti-sn65dsi86: Add NO_CONNECTOR support

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Rob,

Thank you for the patch.

On Mon, Sep 20, 2021 at 03:58:00PM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
> 
> Slightly awkward to fish out the display_info when we aren't creating
> own connector.  But I don't see an obvious better way.
> 
> v2: Remove error return with NO_CONNECTOR flag
> 
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
>  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 39 ++++++++++++++++++++-------
>  1 file changed, 29 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> index 6154bed0af5b..94c94cc8a4d8 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -667,11 +667,6 @@ static int ti_sn_bridge_attach(struct drm_bridge *bridge,
>  						   .node = NULL,
>  						 };
>  
> -	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
> -		DRM_ERROR("Fix bridge driver to make connector optional!");
> -		return -EINVAL;
> -	}
> -
>  	pdata->aux.drm_dev = bridge->dev;
>  	ret = drm_dp_aux_register(&pdata->aux);
>  	if (ret < 0) {
> @@ -679,9 +674,11 @@ static int ti_sn_bridge_attach(struct drm_bridge *bridge,
>  		return ret;
>  	}
>  
> -	ret = ti_sn_bridge_connector_init(pdata);
> -	if (ret < 0)
> -		goto err_conn_init;
> +	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) {
> +		ret = ti_sn_bridge_connector_init(pdata);
> +		if (ret < 0)
> +			goto err_conn_init;
> +	}
>  
>  	/*
>  	 * TODO: ideally finding host resource and dsi dev registration needs
> @@ -743,7 +740,8 @@ static int ti_sn_bridge_attach(struct drm_bridge *bridge,
>  err_dsi_attach:
>  	mipi_dsi_device_unregister(dsi);
>  err_dsi_host:
> -	drm_connector_cleanup(&pdata->connector);
> +	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))
> +		drm_connector_cleanup(&pdata->connector);

I wonder if we actually need this. The connector gets attached to the
encoder, won't it be destroyed by the DRM core in the error path ?

>  err_conn_init:
>  	drm_dp_aux_unregister(&pdata->aux);
>  	return ret;
> @@ -792,9 +790,30 @@ static void ti_sn_bridge_set_dsi_rate(struct ti_sn65dsi86 *pdata)
>  	regmap_write(pdata->regmap, SN_DSIA_CLK_FREQ_REG, val);
>  }
>  
> +/*
> + * Find the connector and fish out the bpc from display_info.  It would
> + * be nice if we could get this instead from drm_bridge_state, but that
> + * doesn't yet appear to be the case.

You already have a bus format in the bridge state, from which you can
derive the bpp. Could you give it a try ?

> + */
>  static unsigned int ti_sn_bridge_get_bpp(struct ti_sn65dsi86 *pdata)
>  {
> -	if (pdata->connector.display_info.bpc <= 6)
> +	struct drm_bridge *bridge = &pdata->bridge;
> +	struct drm_connector_list_iter conn_iter;
> +	struct drm_connector *connector;
> +	unsigned bpc = 0;
> +
> +	drm_connector_list_iter_begin(bridge->dev, &conn_iter);
> +	drm_for_each_connector_iter(connector, &conn_iter) {
> +		if (drm_connector_has_possible_encoder(connector, bridge->encoder)) {
> +			bpc = connector->display_info.bpc;
> +			break;
> +		}
> +	}
> +	drm_connector_list_iter_end(&conn_iter);
> +
> +	WARN_ON(bpc == 0);
> +
> +	if (bpc <= 6)
>  		return 18;
>  	else
>  		return 24;

-- 
Regards,

Laurent Pinchart