[PATCH] drm/vc4: Fix with pm_runtime synchronization on DSI

[PATCH] drm/vc4: Fix with pm_runtime synchronization on DSI

[Hoegeun Kwon]

There is a problem when often dpms goes from off to on. pm idle is not
in sync and the problem occurs. Modify pm_runtime_put from
asynchronous to synchronous.

Signed-off-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
---
 drivers/gpu/drm/vc4/vc4_dsi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
index 11702e1d9011..b0264c7b8bed 100644
--- a/drivers/gpu/drm/vc4/vc4_dsi.c
+++ b/drivers/gpu/drm/vc4/vc4_dsi.c
@@ -822,7 +822,7 @@ static void vc4_dsi_encoder_disable(struct drm_encoder *encoder)
 	clk_disable_unprepare(dsi->escape_clock);
 	clk_disable_unprepare(dsi->pixel_clock);
 
-	pm_runtime_put(dev);
+	pm_runtime_put_sync(dev);
 }
 
 /* Extends the mode's blank intervals to handle BCM2835's integer-only
-- 
2.17.1

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Re: [PATCH] drm/vc4: Fix with pm_runtime synchronization on DSI

[Eric Anholt]

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Hoegeun Kwon <hoegeun.kwon@samsung.com> writes:

> There is a problem when often dpms goes from off to on. pm idle is not
> in sync and the problem occurs. Modify pm_runtime_put from
> asynchronous to synchronous.

Why would we need the power domain to go to off before we try to come
back?  Any idea?  Also, please specify what "the problem" is.

>
> Signed-off-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
> ---
>  drivers/gpu/drm/vc4/vc4_dsi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
> index 11702e1d9011..b0264c7b8bed 100644
> --- a/drivers/gpu/drm/vc4/vc4_dsi.c
> +++ b/drivers/gpu/drm/vc4/vc4_dsi.c
> @@ -822,7 +822,7 @@ static void vc4_dsi_encoder_disable(struct drm_encoder *encoder)
>  	clk_disable_unprepare(dsi->escape_clock);
>  	clk_disable_unprepare(dsi->pixel_clock);
>  
> -	pm_runtime_put(dev);
> +	pm_runtime_put_sync(dev);
>  }
>  
>  /* Extends the mode's blank intervals to handle BCM2835's integer-only
> -- 
> 2.17.1

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Re: [PATCH] drm/vc4: Fix with pm_runtime synchronization on DSI

[Hoegeun Kwon]

On 4/2/19 2:48 AM, Eric Anholt wrote:
> Hoegeun Kwon <hoegeun.kwon@samsung.com> writes:
>
>> There is a problem when often dpms goes from off to on. pm idle is not
>> in sync and the problem occurs. Modify pm_runtime_put from
>> asynchronous to synchronous.
> Why would we need the power domain to go to off before we try to come
> back?  Any idea?  Also, please specify what "the problem" is.

Hi Eric,


First thank you for your review.

There is a problem failed to runtime PM enable on DSI when often dpms

goes from off to on. The cause of this problem is that when we put pm idle,

I think that there is a timing problem if I do not sync.


Best regards,

Hoegeun


>
>> Signed-off-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
>> ---
>>   drivers/gpu/drm/vc4/vc4_dsi.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
>> index 11702e1d9011..b0264c7b8bed 100644
>> --- a/drivers/gpu/drm/vc4/vc4_dsi.c
>> +++ b/drivers/gpu/drm/vc4/vc4_dsi.c
>> @@ -822,7 +822,7 @@ static void vc4_dsi_encoder_disable(struct drm_encoder *encoder)
>>   	clk_disable_unprepare(dsi->escape_clock);
>>   	clk_disable_unprepare(dsi->pixel_clock);
>>   
>> -	pm_runtime_put(dev);
>> +	pm_runtime_put_sync(dev);
>>   }
>>   
>>   /* Extends the mode's blank intervals to handle BCM2835's integer-only
>> -- 
>> 2.17.1
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Re: [PATCH] drm/vc4: Fix with pm_runtime synchronization on DSI

[Eric Anholt]

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Hoegeun Kwon <hoegeun.kwon@samsung.com> writes:

> On 4/2/19 2:48 AM, Eric Anholt wrote:
>> Hoegeun Kwon <hoegeun.kwon@samsung.com> writes:
>>
>>> There is a problem when often dpms goes from off to on. pm idle is not
>>> in sync and the problem occurs. Modify pm_runtime_put from
>>> asynchronous to synchronous.
>> Why would we need the power domain to go to off before we try to come
>> back?  Any idea?  Also, please specify what "the problem" is.
>
> Hi Eric,
>
>
> First thank you for your review.
>
> There is a problem failed to runtime PM enable on DSI when often dpms

What do you mean by "failed to runtime PM enable"?  The
pm_runtime_enable() returned an error?  Have you investigated the source
that error, if so?

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Re: [PATCH] drm/vc4: Fix with pm_runtime synchronization on DSI

[Hoegeun Kwon]

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On 4/10/19 1:24 AM, Eric Anholt wrote:
> Hoegeun Kwon <hoegeun.kwon@samsung.com> writes:
>
>> On 4/2/19 2:48 AM, Eric Anholt wrote:
>>> Hoegeun Kwon <hoegeun.kwon@samsung.com> writes:
>>>
>>>> There is a problem when often dpms goes from off to on. pm idle is not
>>>> in sync and the problem occurs. Modify pm_runtime_put from
>>>> asynchronous to synchronous.
>>> Why would we need the power domain to go to off before we try to come
>>> back?  Any idea?  Also, please specify what "the problem" is.
>> Hi Eric,
>>
>>
>> First thank you for your review.
>>
>> There is a problem failed to runtime PM enable on DSI when often dpms
> What do you mean by "failed to runtime PM enable"?  The
> pm_runtime_enable() returned an error?  Have you investigated the source
> that error, if so?

I'm sorry for the late reply.

The pm_runtime_enable() is not returned because return value is void.

The problem is that if the error log is not output
and the DPMS off on is repeated, the screen will stop.

As a result of debugging the problem, I think that synchronization
is a problem caused by dsi pm_suspend and resume.

So when we entered the pm runtime idle state, if used with sync,
the problem does not occur.

Best regards,
Hoegeun



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Re: [PATCH] drm/vc4: Fix with pm_runtime synchronization on DSI

[Daniel Vetter]

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On Wed, May 22, 2019 at 12:24 PM Hoegeun Kwon <hoegeun.kwon@samsung.com>
wrote:

> On 4/10/19 1:24 AM, Eric Anholt wrote:
>
> Hoegeun Kwon <hoegeun.kwon@samsung.com> <hoegeun.kwon@samsung.com> writes:
>
>
> On 4/2/19 2:48 AM, Eric Anholt wrote:
>
> Hoegeun Kwon <hoegeun.kwon@samsung.com> <hoegeun.kwon@samsung.com> writes:
>
>
> There is a problem when often dpms goes from off to on. pm idle is not
> in sync and the problem occurs. Modify pm_runtime_put from
> asynchronous to synchronous.
>
> Why would we need the power domain to go to off before we try to come
> back?  Any idea?  Also, please specify what "the problem" is.
>
> Hi Eric,
>
>
> First thank you for your review.
>
> There is a problem failed to runtime PM enable on DSI when often dpms
>
> What do you mean by "failed to runtime PM enable"?  The
> pm_runtime_enable() returned an error?  Have you investigated the source
> that error, if so?
>
> I'm sorry for the late reply.
>
> The pm_runtime_enable() is not returned because return value is void.
>
> The problem is that if the error log is not output
> and the DPMS off on is repeated, the screen will stop.
>
> As a result of debugging the problem, I think that synchronization
> is a problem caused by dsi pm_suspend and resume.
>
> So when we entered the pm runtime idle state, if used with sync,
> the problem does not occur.
>
>
Sounds like not enough hystersis between disable/enable, i.e. some msleep
missing somewhere. That's at least my guess, we've had a bunch of these
with delayed runtime suspend of various things in i915.
-Daniel

>
> Best regards,
> Hoegeun
>
>
>
>
>
>
>


-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch

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