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

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Message-ID: <zqmpodwfmabxpjtyhbbuiqkkgaggv3sif7iidv4epjswfw7chp@jomwcvififxk>
Date: Mon, 23 Sep 2024 15:05:45 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: zhaoxiong lv <lvzhaoxiong@...qin.corp-partner.google.com>
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 23, 2024 at 05:22:11PM GMT, zhaoxiong lv wrote:
> 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 should go to the commit message, rewritten to use imperative
language, with the appropriate Fixes tags.

> 
> 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

-- 
With best wishes
Dmitry