linux-kernel - Re: [PATCH v3 3/3] drm/panel-edp: Add some panels with conservative timings

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Date: Mon, 18 Dec 2023 08:42:20 -0800
From: Doug Anderson <dianders@...omium.org>
To: Pin-yen Lin <treapking@...omium.org>
Cc: Neil Armstrong <neil.armstrong@...aro.org>, Jessica Zhang <quic_jesszhan@...cinc.com>, 
	Sam Ravnborg <sam@...nborg.org>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, Guenter Roeck <groeck@...omium.org>, 
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/3] drm/panel-edp: Add some panels with conservative timings

Hi,

On Thu, Dec 14, 2023 at 7:28 AM Pin-yen Lin <treapking@...omium.org> wrote:
>
> These panels are used by Mediatek MT8173 Chromebooks, and they used to
> work with the downstream v4.19 kernel without any specified delay.
> Back in the v4.19 kernel, they used the "little white lie" approach,
> which is making the devicetree claim a specific panel's compatible
> string for many different panels. That was a common solution before the
> generic edp-panel driver.
>
> After we uprevved the device to a newer kernel and used the edp-panel
> driver, we saw multiple devices reporting warnings of using an unknown
> panel and falling back to the conservative timings, which means that
> they turn on/off much more slowly than they should. We tried to fill in
> the timings for those panels, but we failed to find all the data sheets
> for them.
>
> Therefore, instead of having them use the default conservative timings,
> update them with less-conservative timings from other panels of the same
> vendor. The panels should still work under those timings, and we can
> save some delays and suppress the warnings.
>
> Signed-off-by: Pin-yen Lin <treapking@...omium.org>
> Reviewed-by: Douglas Anderson <dianders@...omium.org>
>
> ---
>
> Changes in v3:
> - Update the commit message.
> - Collect review tag.
>
>  drivers/gpu/drm/panel/panel-edp.c | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)

Pushed to drm-misc-next:

7c8690d8fc80 drm/panel-edp: Add some panels with conservative timings