linux-kernel - Re: [PATCH RFC] drm/panel-edp: add fat warning against adding new panel compatibles

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Message-ID: <b55df123-4e22-4cba-b36f-41b4cf117e15@linaro.org>
Date: Thu, 23 May 2024 09:30:34 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
 Douglas Anderson <dianders@...omium.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>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] drm/panel-edp: add fat warning against adding new
 panel compatibles

On 23/05/2024 00:07, Dmitry Baryshkov wrote:
> Add a fat warning against adding new panel compatibles to the panel-edp
> driver. All new users of the eDP panels are supposed to use the generic
> "edp-panel" compatible device on the AUX bus. The remaining compatibles
> are either used by the existing DT or were used previously and are
> retained for backwards compatibility.
> 
> Suggested-by: Doug Anderson <dianders@...omium.org>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> ---
> The following compatibles were never used by the devices supported by
> the upstream kernel and are a subject to possible removal:
> 
> - auo,b133han05
> - auo,b140han06
> - ivo,m133nwf4-r0
> - lg,lp097qx1-spa1
> - lg,lp129qe
> - samsung,lsn122dl01-c01
> - samsung,ltn140at29-301
> - sharp,ld-d5116z01b
> - sharp,lq140m1jw46
> - starry,kr122ea0sra
> 
> I'm considering dropping them, unless there is a good reason not to do
> so.
> ---
>   drivers/gpu/drm/panel/panel-edp.c | 18 +++++++++++++++++-
>   1 file changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
> index 6db277efcbb7..95b25ec67168 100644
> --- a/drivers/gpu/drm/panel/panel-edp.c
> +++ b/drivers/gpu/drm/panel/panel-edp.c
> @@ -1776,7 +1776,23 @@ static const struct of_device_id platform_of_match[] = {
>   	{
>   		/* Must be first */
>   		.compatible = "edp-panel",
> -	}, {
> +	},
> +	/*
> +	 * Do not add panels to the list below unless they cannot be handled by
> +	 * the generic edp-panel compatible.
> +	 *
> +	 * The only two valid reasons are:
> +	 * - because of the panel issues (e.g. broken EDID or broken
> +	 *   identification),
> +	 * - because the platform which uses the panel didn't wire up the AUX
> +	 *   bus properly.
> +	 *
> +	 * In all other cases the platform should use the aux-bus and declare
> +	 * the panel using the 'edp-panel' compatible as a device on the AUX
> +	 * bus. The lack of the aux-bus support is not a valid case. Platforms
> +	 * are urged to be converted to declaring panels in a proper way.
> +	 */
> +	{
>   		.compatible = "auo,b101ean01",
>   		.data = &auo_b101ean01,
>   	}, {
> 
> ---
> base-commit: 8314289a8d50a4e05d8ece1ae0445a3b57bb4d3b
> change-id: 20240523-edp-panel-drop-00aa239b3c6b
> 
> Best regards,

Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>