linux-kernel - Re: [PATCH v1] drm/panel-edp: Add panels with conservative timings

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Message-ID: <CAD=FV=XM7X5J6rzu5gDdmDhJ4Ut8raC92HvcnHmRJmWY7_boSA@mail.gmail.com>
Date: Wed, 17 Jul 2024 07:58:29 -0700
From: Doug Anderson <dianders@...omium.org>
To: Terry Hsiao <terry_hsiao@...pal.corp-partner.google.com>
Cc: linux-kernel@...r.kernel.org, Neil Armstrong <neil.armstrong@...aro.org>, 
	Jessica Zhang <quic_jesszhan@...cinc.com>, 
	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>, 
	dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v1] drm/panel-edp: Add panels with conservative timings

Hi,

On Wed, Jul 17, 2024 at 2:39 AM Terry Hsiao
<terry_hsiao@...pal.corp-partner.google.com> wrote:
>
> The 6 panels are used on Mediatek MT8186 Chromebooks
> - B116XAT04.1  (06AF/B4C4)
> - NV116WHM-A4D (09E5/FA0C)
> - N116BCP-EA2  (0DAE/6111)
> - B116XTN02.3  (06AF/AA73)
> - B116XAN06.1  (06AF/99A1)
> - N116BCA-EA2  (0DAE/5D11)
>
> Signed-off-by: Terry Hsiao <terry_hsiao@...pal.corp-partner.google.com>
> ---
>  drivers/gpu/drm/panel/panel-edp.c | 6 ++++++
>  1 file changed, 6 insertions(+)

Please resend with a better patch subject, like "drm/panel-edp: Add 6
panels used by MT8186 Chromebooks".

Also: are you adding timings based on the datasheets, or are you just
guessing here? The previous patches that added "conservative" timings
were because the Chromebooks involved were really old and couldn't be
tracked down and folks couldn't find the relevant datasheets. In the
case of MT8188 I'd expect you to be adding timings based on the
datasheets. Please confirm that you are.

If possible, it's really nice to have the raw EDIDs for the panels in
the commit message in case someone needs it later.


> diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
> index f85a6404ba58..ac280607998f 100644
> --- a/drivers/gpu/drm/panel/panel-edp.c
> +++ b/drivers/gpu/drm/panel/panel-edp.c
> @@ -1845,8 +1845,11 @@ static const struct edp_panel_entry edp_panels[] = {
>         EDP_PANEL_ENTRY('A', 'U', 'O', 0x635c, &delay_200_500_e50, "B116XAN06.3"),
>         EDP_PANEL_ENTRY('A', 'U', 'O', 0x639c, &delay_200_500_e50, "B140HAK02.7"),
>         EDP_PANEL_ENTRY('A', 'U', 'O', 0x723c, &delay_200_500_e50, "B140XTN07.2"),
> +       EDP_PANEL_ENTRY('A', 'U', 'O', 0x73aa, &delay_200_500_e50, "B116XTN02.3"),
>         EDP_PANEL_ENTRY('A', 'U', 'O', 0x8594, &delay_200_500_e50, "B133UAN01.0"),
>         EDP_PANEL_ENTRY('A', 'U', 'O', 0xd497, &delay_200_500_e50, "B120XAN01.0"),
> +       EDP_PANEL_ENTRY('A', 'U', 'O', 0xa199, &delay_200_500_e50, "B116XAN06.1"),

Please keep this sorted. For instance, 0xa199 should come _before_
0xd497, right?


> +       EDP_PANEL_ENTRY('A', 'U', 'O', 0xc4b4, &delay_200_500_e50, "B116XAT04.1"),
>         EDP_PANEL_ENTRY('A', 'U', 'O', 0xf390, &delay_200_500_e50, "B140XTN07.7"),
>
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0607, &delay_200_500_e200, "Unknown"),
> @@ -1901,6 +1904,7 @@ static const struct edp_panel_entry edp_panels[] = {
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0b56, &delay_200_500_e80, "NT140FHM-N47"),
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0c20, &delay_200_500_e80, "NT140FHM-N47"),
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0cb6, &delay_200_500_e200, "NT116WHM-N44"),
> +       EDP_PANEL_ENTRY('B', 'O', 'E', 0x0cfa, &delay_200_500_e50, "NV116WHM-A4D"),
>
>         EDP_PANEL_ENTRY('C', 'M', 'N', 0x1130, &delay_200_500_e50, "N116BGE-EB2"),
>         EDP_PANEL_ENTRY('C', 'M', 'N', 0x1132, &delay_200_500_e80_d50, "N116BGE-EA2"),
> @@ -1916,8 +1920,10 @@ static const struct edp_panel_entry edp_panels[] = {
>         EDP_PANEL_ENTRY('C', 'M', 'N', 0x1156, &delay_200_500_e80_d50, "Unknown"),
>         EDP_PANEL_ENTRY('C', 'M', 'N', 0x1157, &delay_200_500_e80_d50, "N116BGE-EA2"),
>         EDP_PANEL_ENTRY('C', 'M', 'N', 0x115b, &delay_200_500_e80_d50, "N116BCN-EB1"),
> +       EDP_PANEL_ENTRY('C', 'M', 'N', 0x115d, &delay_200_500_e80_d50, "N116BCA-EA2"),
>         EDP_PANEL_ENTRY('C', 'M', 'N', 0x115e, &delay_200_500_e80_d50, "N116BCA-EA1"),
>         EDP_PANEL_ENTRY('C', 'M', 'N', 0x1160, &delay_200_500_e80_d50, "N116BCJ-EAK"),
> +       EDP_PANEL_ENTRY('C', 'M', 'N', 0x1161, &delay_200_500_e80, "N116BCP-EA2"),

It looks suspicious that all the panels around this one need 50 ms for
disable but yours doesn't. While it's certainly possible that things
changed for this panel, it's worth double-checking.

-Doug