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Message-ID: <95bf8d3b-3daf-c505-eeb0-e5ef167085ac@collabora.com>
Date: Fri, 17 Apr 2020 16:51:08 +0200
From: Enric Balletbo i Serra <enric.balletbo@...labora.com>
To: Laurent Pinchart <laurent.pinchart@...asonboard.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 Laurent,
On 16/4/20 19:22, Laurent Pinchart wrote:
> 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 ?
It is possible but IMHO opinion this is hardware tricky, I mean, ps8640 outputs
eDP interface and the panel is an eDP interface, so I'd expect hardware
engineers do a pin to pin design, not routing the DDC signals to the SoC
directly ignoring the eDP interface.
> 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;
>>
>
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