linux-kernel - Re: [PATCH] drm/panel-edp: Allow querying the detected panel via sysfs

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Message-ID: <e89dbc7b-b3ae-c334-b704-f5633725c29f@redhat.com>
Date:   Tue, 25 Jan 2022 23:55:35 +0100
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     Douglas Anderson <dianders@...omium.org>,
        dri-devel@...ts.freedesktop.org
Cc:     David Airlie <airlied@...ux.ie>, robert.foss@...aro.org,
        linux-kernel@...r.kernel.org,
        Thierry Reding <thierry.reding@...il.com>, jjsu@...omium.org,
        lschyi@...omium.org, Sam Ravnborg <sam@...nborg.org>
Subject: Re: [PATCH] drm/panel-edp: Allow querying the detected panel via
 sysfs

Hello Doug,

On 1/25/22 22:54, Douglas Anderson wrote:
> Recently we added generic "edp-panel"s probed by EDID. To support
> panels in this way we look at the panel ID in the EDID and look up the
> panel in a table that has power sequence timings. If we find a panel
> that's not in the table we will still attempt to use it but we'll use
> conservative timings. While it's likely that these conservative
> timings will work for most nearly all panels, the performance of
> turning the panel off and on suffers.
> 
> We'd like to be able to reliably detect the case that we're using the
> hardcoded timings without relying on parsing dmesg. This allows us to
> implement tests that ensure that no devices get shipped that are
> relying on the conservative timings.
> 
> Let's add a new sysfs entry to panel devices. It will have one of:
> * UNKNOWN - We tried to detect a panel but it wasn't in our table.
> * HARDCODED - We're not using generic "edp-panel" probed by EDID.
> * A panel name - This is the name of the panel from our table.
> 
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---

Patch looks good to me.

Reviewed-by: Javier Martinez Canillas <javierm@...hat.com>

Should this new sysfs entry be documented in Documentation/ABI/ ?

Best regards,
-- 
Javier Martinez Canillas
Linux Engineering
Red Hat