linux-kernel - Re: [PATCH v1 1/2] drm/panel: jd9365da: Modify Kingdisplay and Melfas panel timing

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Message-ID: <CA+6=WdS4i3tWei=zzfS_-OW8hs-tgnifOLbNCirGpTx61xEtCQ@mail.gmail.com>
Date: Mon, 23 Sep 2024 17:22:11 +0800
From: zhaoxiong lv <lvzhaoxiong@...qin.corp-partner.google.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: neil.armstrong@...aro.org, quic_jesszhan@...cinc.com, sam@...nborg.org, 
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de, 
	airlied@...il.com, simona@...ll.ch, dianders@...omium.org, hsinyi@...gle.com, 
	awarnecke002@...mail.com, dri-devel@...ts.freedesktop.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/2] drm/panel: jd9365da: Modify Kingdisplay and Melfas
 panel timing

On Mon, Sep 16, 2024 at 1:11 PM Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> On Sun, 15 Sept 2024 at 10:10, Zhaoxiong Lv
> <lvzhaoxiong@...qin.corp-partner.google.com> wrote:
> >
> > In order to meet the timing, remove the delay between "backlight off"
> > and "display off"
> >
> > Removing variables: display_off_to_enter_sleep_delay_ms
>
> This is not enough. If this is a fix, then describe why the original
> commit is incorrect, provide necessary explanation, details, etc.
> Otherwise it looks as if you are removing the delay that was necessary
> for other panels
>
> Also if this is a fix, it should be properly notated with the Fixes
> tag, maybe cc:stable, etc.
>
> In its current state: NAK.

hi Dmitry

Our machine encountered an issue where, after entering S3 in the black
screen state, there is a probability that the screen remains black
after waking up. It seems that the DRM runtime resume has not yet
completed, but the system has already started the suspend process.
After reducing the delay for disable, this issue no longer occurs,
Therefore, under the premise of meeting the timing requirements, we
removed the delay between "backlight off" and "display off".

Previously,  "backlight_off_to_display_off_delay_ms" was added between
"backlight off" and "display off"  to prevent "display off" from being
executed when the backlight is not fully powered off, which may cause
a white screen. However, we removed this
"backlight_off_to_display_off_delay_ms" and found that this situation
did not occur. Therefore, in order to solve the problem mentioned
above, we removed this delay.

This is the timing specification for the two panels:
1.  Kingdisplay panel timing spec:
https://github.com/KD54183/-JD9365DA_Power-On-Off-Sequence_V0120240923
2.  LMFBX101117480 timing spec: https://github.com/chiohsin-lo/TDY-JD_LIB

thanks

>
> >
> > Signed-off-by: Zhaoxiong Lv <lvzhaoxiong@...qin.corp-partner.google.com>
> > ---
> >  drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c | 6 ------
> >  1 file changed, 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c b/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
> > index 44897e5218a6..2f8af86bc2a0 100644
> > --- a/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
> > +++ b/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
> > @@ -31,7 +31,6 @@ struct jadard_panel_desc {
> >         bool reset_before_power_off_vcioo;
> >         unsigned int vcioo_to_lp11_delay_ms;
> >         unsigned int lp11_to_reset_delay_ms;
> > -       unsigned int backlight_off_to_display_off_delay_ms;
> >         unsigned int display_off_to_enter_sleep_delay_ms;
> >         unsigned int enter_sleep_to_reset_down_delay_ms;
> >  };
> > @@ -69,9 +68,6 @@ static int jadard_disable(struct drm_panel *panel)
> >         struct jadard *jadard = panel_to_jadard(panel);
> >         struct mipi_dsi_multi_context dsi_ctx = { .dsi = jadard->dsi };
> >
> > -       if (jadard->desc->backlight_off_to_display_off_delay_ms)
> > -               mipi_dsi_msleep(&dsi_ctx, jadard->desc->backlight_off_to_display_off_delay_ms);
> > -
> >         mipi_dsi_dcs_set_display_off_multi(&dsi_ctx);
> >
> >         if (jadard->desc->display_off_to_enter_sleep_delay_ms)
> > @@ -858,7 +854,6 @@ static const struct jadard_panel_desc kingdisplay_kd101ne3_40ti_desc = {
> >         .reset_before_power_off_vcioo = true,
> >         .vcioo_to_lp11_delay_ms = 5,
> >         .lp11_to_reset_delay_ms = 10,
> > -       .backlight_off_to_display_off_delay_ms = 100,
> >         .display_off_to_enter_sleep_delay_ms = 50,
> >         .enter_sleep_to_reset_down_delay_ms = 100,
> >  };
> > @@ -1109,7 +1104,6 @@ static const struct jadard_panel_desc melfas_lmfbx101117480_desc = {
> >         .reset_before_power_off_vcioo = true,
> >         .vcioo_to_lp11_delay_ms = 5,
> >         .lp11_to_reset_delay_ms = 10,
> > -       .backlight_off_to_display_off_delay_ms = 100,
> >         .display_off_to_enter_sleep_delay_ms = 50,
> >         .enter_sleep_to_reset_down_delay_ms = 100,
> >  };
> > --
> > 2.17.1
> >
>
>
> --
> With best wishes
> Dmitry