In MTK chips, if the system starts suspending before the DRM runtime 
resume has not completed, there is a possibility of a black screen 
after waking the machine. Reduce the disable delay resolves this issue, 

The "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 We reduced it from 100ms to 3ms (tCMD_OFF >= 1ms).

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


Fixes: 2b976ad760dc ("drm/panel: jd9365da: Support for kd101ne3-40ti MIPI-DSI panel")
Fixes: c4ce398cf18a ("drm/panel: jd9365da: Support for Melfas lmfbx101117480 MIPI-DSI panel")

Signed-off-by: Zhaoxiong Lv <lvzhaoxiong@huaqin.corp-partner.google.com>
---
Changes between V2 and V1:
-  1. Modify the commit message 
-  2. Modify the value of backlight_off_to_display_off_delay_ms.
v1: https://lore.kernel.org/all/20240915080830.11318-2-lvzhaoxiong@huaqin.corp-partner.google.com/
---
 drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c | 4 ++--
 1 file changed, 2 insertions(+), 2 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..486aa20e5518 100644
--- a/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
+++ b/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
@@ -858,7 +858,7 @@ 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,
+	.backlight_off_to_display_off_delay_ms = 3,
 	.display_off_to_enter_sleep_delay_ms = 50,
 	.enter_sleep_to_reset_down_delay_ms = 100,
 };
@@ -1109,7 +1109,7 @@ 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,
+	.backlight_off_to_display_off_delay_ms = 3,
 	.display_off_to_enter_sleep_delay_ms = 50,
 	.enter_sleep_to_reset_down_delay_ms = 100,
 };
-- 
2.17.1

On 9/23/2024 6:42 AM, Zhaoxiong Lv wrote:
> In MTK chips, if the system starts suspending before the DRM runtime
> resume has not completed, there is a possibility of a black screen
> after waking the machine. Reduce the disable delay resolves this issue,

Hi Zhaoxiong,

Do you mean "if the system starts suspending before the DRM runtime 
resume *has* completed" here?

> 
> The "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 We reduced it from 100ms to 3ms (tCMD_OFF >= 1ms).

So from my understanding of this paragraph, 
`backlight_off_to_display_off_delay_ms` was added to prevent the display 
powering off before backlight is fully powered off. You recently tested 
dropping this completely and saw no issue with this.

If that's the case, why not drop this delay completely?

Thanks,

Jessica Zhang

> 
> 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
> 
> 
> Fixes: 2b976ad760dc ("drm/panel: jd9365da: Support for kd101ne3-40ti MIPI-DSI panel")
> Fixes: c4ce398cf18a ("drm/panel: jd9365da: Support for Melfas lmfbx101117480 MIPI-DSI panel")
> 
> Signed-off-by: Zhaoxiong Lv <lvzhaoxiong@huaqin.corp-partner.google.com>
> ---
> Changes between V2 and V1:
> -  1. Modify the commit message
> -  2. Modify the value of backlight_off_to_display_off_delay_ms.
> v1: https://lore.kernel.org/all/20240915080830.11318-2-lvzhaoxiong@huaqin.corp-partner.google.com/
> ---
>   drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 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..486aa20e5518 100644
> --- a/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
> +++ b/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
> @@ -858,7 +858,7 @@ 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,
> +	.backlight_off_to_display_off_delay_ms = 3,
>   	.display_off_to_enter_sleep_delay_ms = 50,
>   	.enter_sleep_to_reset_down_delay_ms = 100,
>   };
> @@ -1109,7 +1109,7 @@ 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,
> +	.backlight_off_to_display_off_delay_ms = 3,
>   	.display_off_to_enter_sleep_delay_ms = 50,
>   	.enter_sleep_to_reset_down_delay_ms = 100,
>   };
> -- 
> 2.17.1
>

On Tue, Sep 24, 2024 at 5:14 AM Jessica Zhang <quic_jesszhan@quicinc.com> wrote:
>
>
>
> On 9/23/2024 6:42 AM, Zhaoxiong Lv wrote:
> > In MTK chips, if the system starts suspending before the DRM runtime
> > resume has not completed, there is a possibility of a black screen
> > after waking the machine. Reduce the disable delay resolves this issue,
>
> Hi Zhaoxiong,
>
> Do you mean "if the system starts suspending before the DRM runtime
> resume *has* completed" here?

Hi Jessica

Sorry, my description may not be clear enough. It should be when the
DRM runtime resume has not yet completed and the system enters sleep
mode at the same time.


>
> >
> > The "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 We reduced it from 100ms to 3ms (tCMD_OFF >= 1ms).
>
> So from my understanding of this paragraph,
> `backlight_off_to_display_off_delay_ms` was added to prevent the display
> powering off before backlight is fully powered off. You recently tested
> dropping this completely and saw no issue with this.
>
> If that's the case, why not drop this delay completely?
>
> Thanks,
>
> Jessica Zhang

Yes, there are currently no other issue after removing this delay.
The reason why I didn't completely remove this delay is because the
panel spec states that a delay of more than 1ms  (tCMD_OFF >= 1ms) is
required when entering diaplay_off (0x28H), so I reserved 3ms.

>
> >
> > 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
> >
> >
> > Fixes: 2b976ad760dc ("drm/panel: jd9365da: Support for kd101ne3-40ti MIPI-DSI panel")
> > Fixes: c4ce398cf18a ("drm/panel: jd9365da: Support for Melfas lmfbx101117480 MIPI-DSI panel")
> >
> > Signed-off-by: Zhaoxiong Lv <lvzhaoxiong@huaqin.corp-partner.google.com>
> > ---
> > Changes between V2 and V1:
> > -  1. Modify the commit message
> > -  2. Modify the value of backlight_off_to_display_off_delay_ms.
> > v1: https://lore.kernel.org/all/20240915080830.11318-2-lvzhaoxiong@huaqin.corp-partner.google.com/
> > ---
> >   drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 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..486aa20e5518 100644
> > --- a/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
> > +++ b/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
> > @@ -858,7 +858,7 @@ 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,
> > +     .backlight_off_to_display_off_delay_ms = 3,
> >       .display_off_to_enter_sleep_delay_ms = 50,
> >       .enter_sleep_to_reset_down_delay_ms = 100,
> >   };
> > @@ -1109,7 +1109,7 @@ 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,
> > +     .backlight_off_to_display_off_delay_ms = 3,
> >       .display_off_to_enter_sleep_delay_ms = 50,
> >       .enter_sleep_to_reset_down_delay_ms = 100,
> >   };
> > --
> > 2.17.1
> >
>

On 9/23/2024 7:13 PM, zhaoxiong lv wrote:
> On Tue, Sep 24, 2024 at 5:14 AM Jessica Zhang <quic_jesszhan@quicinc.com> wrote:
>>
>>
>>
>> On 9/23/2024 6:42 AM, Zhaoxiong Lv wrote:
>>> In MTK chips, if the system starts suspending before the DRM runtime
>>> resume has not completed, there is a possibility of a black screen
>>> after waking the machine. Reduce the disable delay resolves this issue,
>>
>> Hi Zhaoxiong,
>>
>> Do you mean "if the system starts suspending before the DRM runtime
>> resume *has* completed" here?
> 
> Hi Jessica
> 
> Sorry, my description may not be clear enough. It should be when the
> DRM runtime resume has not yet completed and the system enters sleep
> mode at the same time.

Got it, yes I think the reworded explanation in your reply is much clearer.

> 
> 
>>
>>>
>>> The "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 We reduced it from 100ms to 3ms (tCMD_OFF >= 1ms).
>>
>> So from my understanding of this paragraph,
>> `backlight_off_to_display_off_delay_ms` was added to prevent the display
>> powering off before backlight is fully powered off. You recently tested
>> dropping this completely and saw no issue with this.
>>
>> If that's the case, why not drop this delay completely?
>>
>> Thanks,
>>
>> Jessica Zhang
> 
> Yes, there are currently no other issue after removing this delay.
> The reason why I didn't completely remove this delay is because the
> panel spec states that a delay of more than 1ms  (tCMD_OFF >= 1ms) is
> required when entering diaplay_off (0x28H), so I reserved 3ms.

Thanks for the clarification -- I see why you included the "(tCMD_OFF >= 
1ms)" part now. Can you please specify in the commit message that the 
tCMD_OFF delay requirement is from the spec?

Also can you remove the extra "We" in "we We reduced it from 100ms to 3ms"?

Thanks,

Jessica Zhang

> 
>>
>>>
>>> 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
>>>
>>>
>>> Fixes: 2b976ad760dc ("drm/panel: jd9365da: Support for kd101ne3-40ti MIPI-DSI panel")
>>> Fixes: c4ce398cf18a ("drm/panel: jd9365da: Support for Melfas lmfbx101117480 MIPI-DSI panel")
>>>
>>> Signed-off-by: Zhaoxiong Lv <lvzhaoxiong@huaqin.corp-partner.google.com>
>>> ---
>>> Changes between V2 and V1:
>>> -  1. Modify the commit message
>>> -  2. Modify the value of backlight_off_to_display_off_delay_ms.
>>> v1: https://lore.kernel.org/all/20240915080830.11318-2-lvzhaoxiong@huaqin.corp-partner.google.com/
>>> ---
>>>    drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c | 4 ++--
>>>    1 file changed, 2 insertions(+), 2 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..486aa20e5518 100644
>>> --- a/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
>>> +++ b/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
>>> @@ -858,7 +858,7 @@ 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,
>>> +     .backlight_off_to_display_off_delay_ms = 3,
>>>        .display_off_to_enter_sleep_delay_ms = 50,
>>>        .enter_sleep_to_reset_down_delay_ms = 100,
>>>    };
>>> @@ -1109,7 +1109,7 @@ 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,
>>> +     .backlight_off_to_display_off_delay_ms = 3,
>>>        .display_off_to_enter_sleep_delay_ms = 50,
>>>        .enter_sleep_to_reset_down_delay_ms = 100,
>>>    };
>>> --
>>> 2.17.1
>>>
>>

On Wed, Sep 25, 2024 at 12:11 AM Jessica Zhang
<quic_jesszhan@quicinc.com> wrote:
>
>
>
> On 9/23/2024 7:13 PM, zhaoxiong lv wrote:
> > On Tue, Sep 24, 2024 at 5:14 AM Jessica Zhang <quic_jesszhan@quicinc.com> wrote:
> >>
> >>
> >>
> >> On 9/23/2024 6:42 AM, Zhaoxiong Lv wrote:
> >>> In MTK chips, if the system starts suspending before the DRM runtime
> >>> resume has not completed, there is a possibility of a black screen
> >>> after waking the machine. Reduce the disable delay resolves this issue,
> >>
> >> Hi Zhaoxiong,
> >>
> >> Do you mean "if the system starts suspending before the DRM runtime
> >> resume *has* completed" here?
> >
> > Hi Jessica
> >
> > Sorry, my description may not be clear enough. It should be when the
> > DRM runtime resume has not yet completed and the system enters sleep
> > mode at the same time.
>
> Got it, yes I think the reworded explanation in your reply is much clearer.
>
> >
> >
> >>
> >>>
> >>> The "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 We reduced it from 100ms to 3ms (tCMD_OFF >= 1ms).
> >>
> >> So from my understanding of this paragraph,
> >> `backlight_off_to_display_off_delay_ms` was added to prevent the display
> >> powering off before backlight is fully powered off. You recently tested
> >> dropping this completely and saw no issue with this.
> >>
> >> If that's the case, why not drop this delay completely?
> >>
> >> Thanks,
> >>
> >> Jessica Zhang
> >
> > Yes, there are currently no other issue after removing this delay.
> > The reason why I didn't completely remove this delay is because the
> > panel spec states that a delay of more than 1ms  (tCMD_OFF >= 1ms) is
> > required when entering diaplay_off (0x28H), so I reserved 3ms.
>
> Thanks for the clarification -- I see why you included the "(tCMD_OFF >=
> 1ms)" part now. Can you please specify in the commit message that the
> tCMD_OFF delay requirement is from the spec?
>
> Also can you remove the extra "We" in "we We reduced it from 100ms to 3ms"?
>
> Thanks,
>
> Jessica Zhang

OK, thanks for your correction, we will modify the commit message in
the next patch.

>
> >
> >>
> >>>
> >>> 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
> >>>
> >>>
> >>> Fixes: 2b976ad760dc ("drm/panel: jd9365da: Support for kd101ne3-40ti MIPI-DSI panel")
> >>> Fixes: c4ce398cf18a ("drm/panel: jd9365da: Support for Melfas lmfbx101117480 MIPI-DSI panel")
> >>>
> >>> Signed-off-by: Zhaoxiong Lv <lvzhaoxiong@huaqin.corp-partner.google.com>
> >>> ---
> >>> Changes between V2 and V1:
> >>> -  1. Modify the commit message
> >>> -  2. Modify the value of backlight_off_to_display_off_delay_ms.
> >>> v1: https://lore.kernel.org/all/20240915080830.11318-2-lvzhaoxiong@huaqin.corp-partner.google.com/
> >>> ---
> >>>    drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c | 4 ++--
> >>>    1 file changed, 2 insertions(+), 2 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..486aa20e5518 100644
> >>> --- a/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
> >>> +++ b/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
> >>> @@ -858,7 +858,7 @@ 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,
> >>> +     .backlight_off_to_display_off_delay_ms = 3,
> >>>        .display_off_to_enter_sleep_delay_ms = 50,
> >>>        .enter_sleep_to_reset_down_delay_ms = 100,
> >>>    };
> >>> @@ -1109,7 +1109,7 @@ 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,
> >>> +     .backlight_off_to_display_off_delay_ms = 3,
> >>>        .display_off_to_enter_sleep_delay_ms = 50,
> >>>        .enter_sleep_to_reset_down_delay_ms = 100,
> >>>    };
> >>> --
> >>> 2.17.1
> >>>
> >>
>