linux-kernel - Re: [PATCH v2 1/7] drm/bridge: ps8640: Get the EDID from eDP control

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Message-ID: <20200416172215.GK4796@pendragon.ideasonboard.com>
Date:   Thu, 16 Apr 2020 20:22:15 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     linux-kernel@...r.kernel.org,
        Collabora Kernel ML <kernel@...labora.com>,
        matthias.bgg@...il.com, drinkcat@...omium.org, hsinyi@...omium.org,
        Andrzej Hajda <a.hajda@...sung.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Jonas Karlman <jonas@...boo.se>,
        Neil Armstrong <narmstrong@...libre.com>,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v2 1/7] drm/bridge: ps8640: Get the EDID from eDP control

Hi Enric,

Thank you for the patch.

On Thu, Apr 16, 2020 at 05:57:13PM +0200, Enric Balletbo i Serra wrote:
> The PS8640 DSI-to-eDP bridge can retrieve the EDID, so implement the
> .get_edid callback and set the flag to indicate the core to use it.
> 
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
> ---
> 
> Changes in v2: None
> 
>  drivers/gpu/drm/bridge/parade-ps8640.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
> index d3a53442d449..956b76e0a44d 100644
> --- a/drivers/gpu/drm/bridge/parade-ps8640.c
> +++ b/drivers/gpu/drm/bridge/parade-ps8640.c
> @@ -242,8 +242,18 @@ static int ps8640_bridge_attach(struct drm_bridge *bridge,
>  	return ret;
>  }
>  
> +static struct edid *ps8640_bridge_get_edid(struct drm_bridge *bridge,
> +					   struct drm_connector *connector)
> +{
> +	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
> +
> +	return drm_get_edid(connector,
> +			    ps_bridge->page[PAGE0_DP_CNTL]->adapter);

This will only work if the DDC signals are connected to the PS8640
(quite obviously). Is that guaranteed, or could some systems connect
them directory to an SoC I2C controller ? In the latter case we would
have to report this in the DT bindings of the PS8640. That's not
blocking for this patch, I am just wondering, as I would have expected
the driver to already expose EDID one way or another if this was
available and used.

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> +}
> +
>  static const struct drm_bridge_funcs ps8640_bridge_funcs = {
>  	.attach = ps8640_bridge_attach,
> +	.get_edid = ps8640_bridge_get_edid,
>  	.post_disable = ps8640_post_disable,
>  	.pre_enable = ps8640_pre_enable,
>  };
> @@ -296,6 +306,8 @@ static int ps8640_probe(struct i2c_client *client)
>  
>  	ps_bridge->bridge.funcs = &ps8640_bridge_funcs;
>  	ps_bridge->bridge.of_node = dev->of_node;
> +	ps_bridge->bridge.ops = DRM_BRIDGE_OP_EDID;
> +	ps_bridge->bridge.type = DRM_MODE_CONNECTOR_eDP;
>  
>  	ps_bridge->page[PAGE0_DP_CNTL] = client;
>  

-- 
Regards,

Laurent Pinchart