linux-kernel - Re: [PATCH] drm/panel-edp: Add 50ms disable delay for three panels

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Message-ID: <CAD=FV=UMnQLyDxj0q28OEpfcBOX7Fdnn=VbEHLPTgPDBCPjJLg@mail.gmail.com>
Date: Tue, 22 Jul 2025 08:30:02 -0700
From: Doug Anderson <dianders@...omium.org>
To: Langyan Ye <yelangyan@...qin.corp-partner.google.com>
Cc: neil.armstrong@...aro.org, jessica.zhang@....qualcomm.com, 
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de, 
	airlied@...il.com, simona@...ll.ch, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, Sebastian Reichel <sre@...nel.org>
Subject: Re: [PATCH] drm/panel-edp: Add 50ms disable delay for three panels

Hi,

On Mon, Jul 21, 2025 at 7:45 PM Langyan Ye
<yelangyan@...qin.corp-partner.google.com> wrote:
>
> Add 50ms disable delay for NV116WHM-N49, NV122WUM-N41, and MNC207QS1-1
> to satisfy T9+T10 timing.
>
> Fixes: 0547692ac146 ("drm/panel-edp: Add several generic edp panels")
> Signed-off-by: Langyan Ye <yelangyan@...qin.corp-partner.google.com>
> ---
>  drivers/gpu/drm/panel/panel-edp.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
> index 09170470b3ef..742a83fa4da1 100644
> --- a/drivers/gpu/drm/panel/panel-edp.c
> +++ b/drivers/gpu/drm/panel/panel-edp.c
> @@ -1743,6 +1743,14 @@ static const struct panel_delay delay_200_500_e50_p2e200 = {
>         .prepare_to_enable = 200,
>  };
>
> +static const struct panel_delay delay_200_500_e50_d50_p2e200 = {
> +       .hpd_absent = 200,
> +       .unprepare = 500,
> +       .enable = 50,
> +       .disable = 50,
> +       .prepare_to_enable = 200,
> +};
> +
>  static const struct panel_delay delay_200_500_e80 = {
>         .hpd_absent = 200,
>         .unprepare = 500,
> @@ -1941,13 +1949,13 @@ static const struct edp_panel_entry edp_panels[] = {
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x09dd, &delay_200_500_e50, "NT116WHM-N21"),
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0a1b, &delay_200_500_e50, "NV133WUM-N63"),
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0a36, &delay_200_500_e200, "Unknown"),
> -       EDP_PANEL_ENTRY('B', 'O', 'E', 0x0a3e, &delay_200_500_e80, "NV116WHM-N49"),
> +       EDP_PANEL_ENTRY('B', 'O', 'E', 0x0a3e, &delay_200_500_e80_d50, "NV116WHM-N49"),
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0a5d, &delay_200_500_e50, "NV116WHM-N45"),
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0ac5, &delay_200_500_e50, "NV116WHM-N4C"),
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0ae8, &delay_200_500_e50_p2e80, "NV140WUM-N41"),
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0b09, &delay_200_500_e50_po2e200, "NV140FHM-NZ"),
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0b1e, &delay_200_500_e80, "NE140QDM-N6A"),
> -       EDP_PANEL_ENTRY('B', 'O', 'E', 0x0b34, &delay_200_500_e80, "NV122WUM-N41"),
> +       EDP_PANEL_ENTRY('B', 'O', 'E', 0x0b34, &delay_200_500_e80_d50, "NV122WUM-N41"),
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0b43, &delay_200_500_e200, "NV140FHM-T09"),
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0b56, &delay_200_500_e80, "NT140FHM-N47"),
>         EDP_PANEL_ENTRY('B', 'O', 'E', 0x0b66, &delay_200_500_e80, "NE140WUM-N6G"),
> @@ -1986,7 +1994,7 @@ static const struct edp_panel_entry edp_panels[] = {
>         EDP_PANEL_ENTRY('C', 'M', 'N', 0x14e5, &delay_200_500_e80_d50, "N140HGA-EA1"),
>         EDP_PANEL_ENTRY('C', 'M', 'N', 0x162b, &delay_200_500_e80_d50, "N160JCE-ELL"),
>
> -       EDP_PANEL_ENTRY('C', 'S', 'O', 0x1200, &delay_200_500_e50_p2e200, "MNC207QS1-1"),
> +       EDP_PANEL_ENTRY('C', 'S', 'O', 0x1200, &delay_200_500_e50_d50_p2e200, "MNC207QS1-1"),
>         EDP_PANEL_ENTRY('C', 'S', 'O', 0x1413, &delay_200_500_e50_p2e200, "MNE007JA1-2"),

Can you send a v2 where you also change the timings for "MNE007JA1-2"
in the same patch? That also means that instead of adding a new timing
for "delay_200_500_e50_d50_p2e200" you can rename/replace the
"delay_200_500_e50_p2e200" since these are the only two users of that
timing.

Specifically it can be noted that when "MNE007JA1-2" was added [1] it
was done by someone without panel docs so they just copied the other
timings. Adding an extra 50ms delay should be safe and is probably
right for that panel as well.

When you do this then your patch will have two "Fixes" tags, one for
the commit you've already identified and one for commit 50625eab3972
("drm/edp-panel: Add panel used by T14s Gen6 Snapdragon").

[1] https://patchwork.freedesktop.org/patch/msgid/20250211014314.94429-1-sre@ring0.de

-Doug