Re: [PATCH 3/3] drm/panel_edp: Add SEC LTL101DL02-002 panel

[Alexandre Marquet <tb@a-marquet.fr>]

Hi,

Thank you for your feedback.

Le Wed, Oct 28, 2026 at 09:34:15AM -0700, Doug Anderson a écrit :
> Hi,
> 
> On Tue, Oct 27, 2026 at 5:01 AM Alexandre Marquet via B4 Relay
> <devnull+tb.a-marquet.fr@kernel.org> wrote:
> >
> > From: Alexandre Marquet <tb@a-marquet.fr>
> >
> > Add an entry for the eDP SEC LTL101DL02-002 panel used in
> > google-manta.
> >
> > Raw EDID dump:
> >
> > 00 ff ff ff ff ff ff 00 4c a3 0f 9c 00 00 00 00
> > 05 0e 01 03 80 21 19 78 0a 87 fe 98 57 51 8c 27
> > 21 50 54 00 00 00 01 01 01 01 01 01 01 01 01 01
> > 01 01 01 01 01 01 14 69 00 a0 a0 40 2e 60 30 20
> > 36 00 1e d6 10 00 00 19 00 00 00 00 00 00 00 00
> > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 9e
> >
> > Signed-off-by: Alexandre Marquet <tb@a-marquet.fr>
> > ---
> >  drivers/gpu/drm/panel/panel-edp.c | 2 ++
> >  1 file changed, 2 insertions(+)
> 
> nit: subject doesn't quite fit the pattern of recent commits (_ vs -).

Apologies for not noticing. I will fix that in v2.

> 
> 
> > diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
> > index 94bc54c3833a..c92985363093 100644
> > --- a/drivers/gpu/drm/panel/panel-edp.c
> > +++ b/drivers/gpu/drm/panel/panel-edp.c
> > @@ -2198,6 +2198,8 @@ static const struct edp_panel_entry edp_panels[] = {
> >         EDP_PANEL_ENTRY('L', 'G', 'D', 0x0778, &delay_200_500_e200_d200, "134WT1"),
> >         EDP_PANEL_ENTRY('L', 'G', 'D', 0x07fe, &delay_200_500_e200_d200, "LP116WHA-SPB1"),
> >
> > +       EDP_PANEL_ENTRY('S', 'E', 'C', 0x9c0f, &delay_200_500_e50, "LTL101DL02-002"),
> > +
> 
> It would also be good to note in the commit message where you got the
> timings from. Datasheet? Downstream code? Guessing?

Both downstream code and guessing, as I could not get my hand on a
datasheet. I will add an explanation to the commit description.

Basically, the downstream code waits: at least 500ms before toggling the LCD_EN
GPIO for power on; and 200ms after. I matched the 200ms to the hpd_absent
delay, since in panel-edp.c, hpd_absent is also the delay that happens
right after enabling the LCD regulator (or toggling the enable GPIO, as
appropriate). Similarly, the unprepare delay is called just before
enabling the LCD regulator, through panel_edp_wait(), which matches the
way the 500ms delay is used in the downstream code.

For the enable delay, I went with the smallest value that would still
work, but I admit that I did not try anything below 50ms.

> 
> I had my AI agent take a look for itself. It found evidence suggesting
> the enable delay should be 97ms, not 50ms. The other ones seem to be
> OK.

In the downstream code, 97ms is the delay used before setting the
backlight on. My understanding is that this should be used elsewhere
(e.g.: in the backlight node of the device's DTS).

> 
> -Doug
Best regards,
Alex.