Re: Regression: i915 blank issue on kernel 3.1.0-rc3

Re: Regression: i915 blank issue on kernel 3.1.0-rc3

[Alex Davis]

I'm having the same problem.

http://marc.info/?l=linux-kernel&m=131695739702141&w=2

Please keep me on the CC list for this thread.

Thanks.


I code, therefore I am

Re: Regression: i915 blank issue on kernel 3.1.0-rc3

[Alex Davis]

>From: Alex Davis <alex14641@yahoo.com>
>To: "terraluna977@gmail.com" <terraluna977@gmail.com>; "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
>Cc: 
>Sent: Sunday, September 25, 2011 9:37 AM
>Subject: Re:  Regression: i915 blank issue on kernel 3.1.0-rc3
>
>I'm having the same problem.
>
>http://marc.info/?l=linux-kernel&m=131695739702141&w=2
>
>Please keep me on the CC list for this thread.
>
>Thanks.
>
>
> I code, therefore I am

The following patch fixed my backlight issues:

diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index a9e0c7b..6f56676 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -262,8 +262,6 @@ void intel_panel_disable_backlight(struct drm_device *dev)
         dev_priv->backlight_level = intel_panel_get_backlight(dev);
         dev_priv->backlight_enabled = false;
     }
-
-    intel_panel_set_backlight(dev, 0);
 }
 
 void intel_panel_enable_backlight(struct drm_device *dev)

I've been using it since yesterday morning with no issues.

Re: Regression: i915 blank issue on kernel 3.1.0-rc3

[Keith Packard]

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On Mon, 3 Oct 2011 14:10:10 -0700 (PDT), Alex Davis <alex14641@yahoo.com> wrote:

> The following patch fixed my backlight issues:
> 
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index a9e0c7b..6f56676 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -262,8 +262,6 @@ void intel_panel_disable_backlight(struct drm_device *dev)
>          dev_priv->backlight_level = intel_panel_get_backlight(dev);
>          dev_priv->backlight_enabled = false;
>      }
> -
> -    intel_panel_set_backlight(dev, 0);
>  }
>  
>  void intel_panel_enable_backlight(struct drm_device *dev)
> 
> I've been using it since yesterday morning with no issues.

Matthew -- if we cannot resolve this backlight issue, we're going to
need to disable the new backlight code for 3.1. Do you want to try and
fix it? Or should we bail for now?

-- 
keith.packard@intel.com

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Re: Regression: i915 blank issue on kernel 3.1.0-rc3

[Alex Davis]

.From: Keith Packard <keithp@keithp.com>
>> The following patch fixed my backlight issues:
>> 
>> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
>> index a9e0c7b..6f56676 100644
>> --- a/drivers/gpu/drm/i915/intel_panel.c
>> +++ b/drivers/gpu/drm/i915/intel_panel.c
>> @@ -262,8 +262,6 @@ void intel_panel_disable_backlight(struct drm_device *dev)
>>          dev_priv->backlight_level = intel_panel_get_backlight(dev);
>>          dev_priv->backlight_enabled = false;
>>      }
>> -
>> -    intel_panel_set_backlight(dev, 0);
>>  }
>>  
>>  void intel_panel_enable_backlight(struct drm_device *dev)
>> 
>> I've been using it since yesterday morning with no issues.
>
>Matthew -- if we cannot resolve this backlight issue, we're going to
>need to disable the new backlight code for 3.1. Do you want to try and
>fix it? Or should we bail for now?

By 'disable', do you mean revert? If so, I would the like chance to submit a patch that adds a boot parameter 
for the driver to disable the backlight by default, e.g: i915_disable_bl. Once the issues are sorted, the
parameter could be removed.

Re: Regression: i915 blank issue on kernel 3.1.0-rc3

[Keith Packard]

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On Wed, 5 Oct 2011 12:59:40 -0700 (PDT), Alex Davis <alex14641@yahoo.com> wrote:

> By 'disable', do you mean revert? If so, I would the like chance to submit a patch that adds a boot parameter 
> for the driver to disable the backlight by default, e.g: i915_disable_bl. Once the issues are sorted, the
> parameter could be removed.

If your machine used to work (with 3.0) and does not work with 3.1-rc,
then we need to fix the driver so that, with no configuration changes,
your machine continues to work. Preventing regressions is our primary
responsibility when changing the drivers.

Does reverting Matthew's backlight patch fix a regression on your machine?

-- 
keith.packard@intel.com

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Re: Regression: i915 blank issue on kernel 3.1.0-rc3

[Alex Davis]

 
I code, therefore I am


----- Original Message -----
From: Keith Packard <keithp@keithp.com>
>> By 'disable', do you mean revert? If so, I would the like chance to submit a patch that adds a boot parameter 
>> for the driver to disable the backlight by default, e.g: i915_disable_bl. Once the issues are sorted, the
>> parameter could be removed.
>
>If your machine used to work (with 3.0) and does not work with 3.1-rc,
>then we need to fix the driver so that, with no configuration changes,
>your machine continues to work. Preventing regressions is our primary
>responsibility when changing the drivers.
The patch I sent in a previous message in this thread makes it work correctly.
If I added an explanation and a 'Signed-by' line, could someone pick it up?

> Does reverting Matthew's backlight patch fix a regression on your machine?
Yes, but I have no backlight control: the screen is too bright to look at comfortably.

Re: Regression: i915 blank issue on kernel 3.1.0-rc3

[Keith Packard]

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On Wed, 5 Oct 2011 14:20:43 -0700 (PDT), Alex Davis <alex14641@yahoo.com> wrote:

> The patch I sent in a previous message in this thread makes it work correctly.
> If I added an explanation and a 'Signed-by' line, could someone pick it up?

It would almost certainly break some other machine. We could, of course,
use a quirk to make your machine work, but that's something of a
last-resort as it won't fix any other machines.

> Yes, but I have no backlight control: the screen is too bright to look at comfortably.

Ok, so the new native backlight driver works, but conflicts with your
previous backlight driver (whatever that was). Adding support for the
native backlight driver (Matthew's patch) and disabling the old
backlight mechanisms makes everything better. Right?

-- 
keith.packard@intel.com

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Re: Regression: i915 blank issue on kernel 3.1.0-rc3

[Alex Davis]

.From: Keith Packard <keithp@keithp.com>
>> The patch I sent in a previous message in this thread makes it work correctly.
>> If I added an explanation and a 'Signed-by' line, could someone pick it up?
>
>It would almost certainly break some other machine. We could, of course,
>use a quirk to make your machine work, but that's something of a
>last-resort as it won't fix any other machines.

>> Yes, but I have no backlight control: the screen is too bright to look at comfortably.
This sounds whiny. I'm sorry about that.

>Ok, so the new native backlight driver works, but conflicts with your
>previous backlight driver (whatever that was).
It does not conflict. The previous backlight driver, dell_backlight, is still present 
on my machine; it just doesn't work, and never did.

> Adding support for the native backlight driver (Matthew's patch) and disabling the old
>backlight mechanisms makes everything better. Right?
No. The patch is against the native backlight code; it's not necessary to disable
the other backlight.

Re: Regression: i915 blank issue on kernel 3.1.0-rc3

[Alex Davis]

I now see that the patch I submitted, while against the native backlight related code, is not against the patch-related code.
I agree that this patch is not suitable for inclusion. 

Re: Regression: i915 blank issue on kernel 3.1.0-rc3

[Alex Davis]

>Matthew - this is your most excellent patch which adds a native
>backlight mechanism. What other info do you need to help figure out how
>to make it play well on other machines? We've got a handful of
>regressions about backligh in the 3.1 RC series, and I'd hate to have to
>revert this...

I'd hate to have it reverted as well. Without this patch, my laptop screen is too bright to 
look at comfortably. Fortunately the workarounds make it usable even in its current state.


I code, therefore I am

Re: Regression: i915 blank issue on kernel 3.1.0-rc3

[Keith Packard]

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On Sun, 25 Sep 2011 10:23:37 -0400, Woody Suwalski <terraluna977@gmail.com> wrote:

> Anyway, for Eeepc reverting the
> 
> aaa6fd2a004147bf32fce05720938236de3361d9
> 
> seems to be fixing the issue. Which is not of course the way we want
> to go ;-(

That's better than something broken in the middle of mode setting.

Matthew - this is your most excellent patch which adds a native
backlight mechanism. What other info do you need to help figure out how
to make it play well on other machines? We've got a handful of
regressions about backligh in the 3.1 RC series, and I'd hate to have to
revert this...

-- 
keith.packard@intel.com

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Re: Regression: i915 blank issue on kernel 3.1.0-rc3

[Woody Suwalski]

Keith Packard wrote:
> On Wed, 21 Sep 2011 19:02:05 -0400, Woody Suwalski<terraluna977@gmail.com>  wrote:
>
>> Chris, I do not know if it is i915 driver or X'drm or what..
>> Problem exists on 3.1.0, no problem on 3.0.3
> Any way you could narrow it down a bit more? A bisect should sort it out
> pretty quickly, given that you've got working code in 3.0 and
> not-working code in 3.1-rc. You can start by manually bisecting across the
> 3.1 release candidates, and then narrow it down from there by bisecting
> only across the drivers/gpu/drm/i915 directory.
>
I see that now more people are reporting a blanker problem. I guess 
kernel.org downtime is really impacting testing...

Anyway, for Eeepc reverting the

aaa6fd2a004147bf32fce05720938236de3361d9

seems to be fixing the issue. Which is not of course the way we want to go ;-(

Woody

Re: Regression: i915 blank issue on kernel 3.1.0-rc3

[Woody Suwalski]

Keith Packard wrote:
> On Wed, 21 Sep 2011 19:02:05 -0400, Woody Suwalski<terraluna977@gmail.com>  wrote:
>
>> Chris, I do not know if it is i915 driver or X'drm or what..
>> Problem exists on 3.1.0, no problem on 3.0.3
> Any way you could narrow it down a bit more? A bisect should sort it out
> pretty quickly, given that you've got working code in 3.0 and
> not-working code in 3.1-rc. You can start by manually bisecting across the
> 3.1 release candidates, and then narrow it down from there by bisecting
> only across the drivers/gpu/drm/i915 directory.
Yes, I have narrowed it down. I did not run bisect, as it takes me 4hrs 
for kernel build on Eeepc...

The problem has appeared in 3.1-rc3, it is a regression.
I have tested -rc1 and -rc2, they are OK ( not that there was much 
activity regarding i915 in -rc2). The problem is still present in -rc7.

I see these entries in the changelog, these are Keith's additions to 
-rc3 which maight impact the blanker:

Keith Packard (6):
       drm/i915: Wait for LVDS panel power sequence
       drm/i915: Leave LVDS registers unlocked
       drm/i915: Fix PCH port pipe select in CPT disable paths
       drm/i915: Remove unused 'reg' argument to dp_pipe_enabled
       drm/i915: Can't do accurate vblank timestamps with UMS
       drm/i915: Cannot set clock gating under UMS

I can do a fast incremental rebuild of my current -rc3 tree, if Keith could send me some patches...

Thanks, Woody