: Changing brightness does not work with v3.16-rc4

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video:
change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

With best regards,
Julian Wollrath

Hi,

Quoted 6 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video:
change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

Quoted 10 lines

Hi,

Quoted 7 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video:
change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

Quoted 5 lines

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

And reverting commit 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1) make that last problem go away, right?

We are going to rever commit 886129a8eebe for other reasons, so can you please revert it from 3.16-rc5 on your system and report back?

Rafael

Am Mon, 14 Jul 2014 20:21:19 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 17 lines · Julian Wollrath

Quoted 15 lines

Hi,

Quoted 7 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video:
change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

Quoted 6 lines

And reverting commit 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1) make that last problem go away, right?

We are going to rever commit 886129a8eebe for other reasons, so can you please revert it from 3.16-rc5 on your system and report back?

Yes, with both 751109aad583 and 886129a8eebe reverted, changing the brightness works again.

Quoted 24 lines · Julian Wollrath

Am Mon, 14 Jul 2014 20:21:19 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 21 lines · Julian Wollrath

Quoted 10 lines

Hi,

Quoted 7 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video:
change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

Quoted 5 lines

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

And reverting commit 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1) make that last problem go away, right?

Quoted 4 lines

Quoted 2 lines

We are going to rever commit 886129a8eebe for other reasons, so can you please revert it from 3.16-rc5 on your system and report back?

Yes, with both 751109aad583 and 886129a8eebe reverted, changing the brightness works again.

What if you revert 886129a8eebe alone?

Quoted 29 lines · Julian Wollrath

Quoted 28 lines

Am Mon, 14 Jul 2014 20:21:19 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 25 lines · Julian Wollrath

Quoted 10 lines

Hi,

Quoted 7 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video: change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

Quoted 6 lines

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

And reverting commit 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1) make that last problem go away, right?

We are going to rever commit 886129a8eebe for other reasons, so can you please revert it from 3.16-rc5 on your system and report back?

Quoted 4 lines

Quoted 2 lines

Yes, with both 751109aad583 and 886129a8eebe reverted, changing the brightness works again.

What if you revert 886129a8eebe alone?

I mean, what exactly do you need to pass to the kernel command line in that case to make brightness switching work?

Am Mon, 14 Jul 2014 21:10:47 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 35 lines · Rafael J. Wysocki

Quoted 33 lines · Julian Wollrath

Quoted 25 lines

Am Mon, 14 Jul 2014 20:21:19 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 22 lines · Julian Wollrath

Quoted 10 lines

Hi,

Quoted 7 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video: change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

Quoted 6 lines

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

And reverting commit 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1) make that last problem go away, right?

Quoted 5 lines

Quoted 3 lines

We are going to rever commit 886129a8eebe for other reasons, so can you please revert it from 3.16-rc5 on your system and report back?

Yes, with both 751109aad583 and 886129a8eebe reverted, changing the brightness works again.

What if you revert 886129a8eebe alone?

Quoted 2 lines

I mean, what exactly do you need to pass to the kernel command line in that case to make brightness switching work?

I need to pass
acpi_osi="!Windows 2012" video.brightness_switch_enabled=1 video.use_native_backlight=-1

If I leave one of these parameters out, the brightness switch stops working.

Quoted 43 lines · Julian Wollrath

Am Mon, 14 Jul 2014 21:10:47 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 30 lines · Rafael J. Wysocki

Quoted 29 lines · Julian Wollrath

Quoted 28 lines

Am Mon, 14 Jul 2014 20:21:19 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 25 lines · Julian Wollrath

Quoted 10 lines

Hi,

Quoted 7 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video: change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

Quoted 6 lines

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

And reverting commit 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1) make that last problem go away, right?

We are going to rever commit 886129a8eebe for other reasons, so can you please revert it from 3.16-rc5 on your system and report back?

Quoted 7 lines

Quoted 4 lines

Quoted 2 lines

Yes, with both 751109aad583 and 886129a8eebe reverted, changing the brightness works again.

What if you revert 886129a8eebe alone?

I mean, what exactly do you need to pass to the kernel command line in that case to make brightness switching work?

I need to pass
acpi_osi="!Windows 2012" video.brightness_switch_enabled=1 video.use_native_backlight=-1

Quoted 2 lines

If I leave one of these parameters out, the brightness switch stops working.

With 886129a8eebe reverted you should not need video.brightness_switch_enabled=1.

Aaron, what do you think?

Quoted 44 lines · Rafael J. Wysocki

Quoted 43 lines · Julian Wollrath

Am Mon, 14 Jul 2014 21:10:47 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 30 lines · Rafael J. Wysocki

Quoted 29 lines · Julian Wollrath

Quoted 28 lines

Am Mon, 14 Jul 2014 20:21:19 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 25 lines · Julian Wollrath

Quoted 10 lines

Hi,

Quoted 7 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video: change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

Quoted 6 lines

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

And reverting commit 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1) make that last problem go away, right?

We are going to rever commit 886129a8eebe for other reasons, so can you please revert it from 3.16-rc5 on your system and report back?

Quoted 7 lines

Quoted 4 lines

Quoted 2 lines

Yes, with both 751109aad583 and 886129a8eebe reverted, changing the brightness works again.

What if you revert 886129a8eebe alone?

I mean, what exactly do you need to pass to the kernel command line in that case to make brightness switching work?

I need to pass
acpi_osi="!Windows 2012" video.brightness_switch_enabled=1 video.use_native_backlight=-1

Quoted 6 lines

Quoted 2 lines

If I leave one of these parameters out, the brightness switch stops working.

With 886129a8eebe reverted you should not need video.brightness_switch_enabled=1.

Aaron, what do you think?

I agree.

I suppose Julian is not using an standard GUI so he needs the in kernel processing of the backlight event. And his laptop has a broken ACPI interface in Win8 mode, so he also needs the "!Windows 2012" option.

With a standard GUI environment, his system would have only one interface left: the GPU one and everything should work. But of course, that may not be his config.

Quoted 58 lines · Aaron Lu

Quoted 44 lines · Rafael J. Wysocki

Quoted 43 lines · Julian Wollrath

Am Mon, 14 Jul 2014 21:10:47 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 30 lines · Rafael J. Wysocki

Quoted 29 lines · Julian Wollrath

Quoted 28 lines

Am Mon, 14 Jul 2014 20:21:19 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 25 lines · Julian Wollrath

Quoted 10 lines

Hi,

Quoted 7 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video: change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

Quoted 6 lines

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

And reverting commit 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1) make that last problem go away, right?

We are going to rever commit 886129a8eebe for other reasons, so can you please revert it from 3.16-rc5 on your system and report back?

Quoted 7 lines

Quoted 4 lines

Quoted 2 lines

Yes, with both 751109aad583 and 886129a8eebe reverted, changing the brightness works again.

What if you revert 886129a8eebe alone?

I mean, what exactly do you need to pass to the kernel command line in that case to make brightness switching work?

I need to pass
acpi_osi="!Windows 2012" video.brightness_switch_enabled=1 video.use_native_backlight=-1

Quoted 6 lines

Quoted 2 lines

If I leave one of these parameters out, the brightness switch stops working.

With 886129a8eebe reverted you should not need video.brightness_switch_enabled=1.

Aaron, what do you think?

I agree.

I suppose Julian is not using an standard GUI so he needs the in kernel processing of the backlight event. And his laptop has a broken ACPI interface in Win8 mode, so he also needs the "!Windows 2012" option.

Quoted 3 lines

With a standard GUI environment, his system would have only one interface left: the GPU one and everything should work. But of course, that may not be his config.

Well, do we need to revert 751109aad583 too, then?

It seems that it may break other systems without a desktop environment, may it not?

Quoted 58 lines · Aaron Lu

Quoted 44 lines · Rafael J. Wysocki

Quoted 43 lines · Julian Wollrath

Am Mon, 14 Jul 2014 21:10:47 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 30 lines · Rafael J. Wysocki

Quoted 29 lines · Julian Wollrath

Quoted 28 lines

Am Mon, 14 Jul 2014 20:21:19 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 25 lines · Julian Wollrath

Quoted 10 lines

Hi,

Quoted 7 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video: change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

Quoted 6 lines

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

And reverting commit 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1) make that last problem go away, right?

We are going to rever commit 886129a8eebe for other reasons, so can you please revert it from 3.16-rc5 on your system and report back?

Quoted 7 lines

Quoted 4 lines

Quoted 2 lines

Yes, with both 751109aad583 and 886129a8eebe reverted, changing the brightness works again.

What if you revert 886129a8eebe alone?

I mean, what exactly do you need to pass to the kernel command line in that case to make brightness switching work?

I need to pass
acpi_osi="!Windows 2012" video.brightness_switch_enabled=1 video.use_native_backlight=-1

Quoted 6 lines

Quoted 2 lines

If I leave one of these parameters out, the brightness switch stops working.

With 886129a8eebe reverted you should not need video.brightness_switch_enabled=1.

Aaron, what do you think?

I agree.

I suppose Julian is not using an standard GUI so he needs the in kernel processing of the backlight event. And his laptop has a broken ACPI interface in Win8 mode, so he also needs the "!Windows 2012" option.

Quoted 3 lines

With a standard GUI environment, his system would have only one interface left: the GPU one and everything should work. But of course, that may not be his config.

Well, do we need to revert 751109aad583 too, then?

If we have to consider the following config:
1 ACPI backlight interface works(or can work with some cmdline option);

2 Not using a normal GUI(depends on ACPI video module to do the in
kernel backlight level change on hotkey press).
Then we will need to revert 751109aad583.

Hi,

Quoted 59 lines · Rafael J. Wysocki

Quoted 58 lines · Aaron Lu

Quoted 44 lines · Rafael J. Wysocki

Quoted 43 lines · Julian Wollrath

Am Mon, 14 Jul 2014 21:10:47 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 30 lines · Rafael J. Wysocki

Quoted 29 lines · Julian Wollrath

Quoted 28 lines

Am Mon, 14 Jul 2014 20:21:19 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 25 lines · Julian Wollrath

Quoted 10 lines

Hi,

Quoted 7 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video: change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

Quoted 6 lines

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

And reverting commit 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1) make that last problem go away, right?

We are going to rever commit 886129a8eebe for other reasons, so can you please revert it from 3.16-rc5 on your system and report back?

Quoted 7 lines

Quoted 4 lines

Quoted 2 lines

Yes, with both 751109aad583 and 886129a8eebe reverted, changing the brightness works again.

What if you revert 886129a8eebe alone?

I mean, what exactly do you need to pass to the kernel command line in that case to make brightness switching work?

I need to pass
acpi_osi="!Windows 2012" video.brightness_switch_enabled=1 video.use_native_backlight=-1

Quoted 6 lines

Quoted 2 lines

If I leave one of these parameters out, the brightness switch stops working.

With 886129a8eebe reverted you should not need video.brightness_switch_enabled=1.

Aaron, what do you think?

I agree.

I suppose Julian is not using an standard GUI so he needs the in kernel processing of the backlight event. And his laptop has a broken ACPI interface in Win8 mode, so he also needs the "!Windows 2012" option.

Quoted 5 lines

Quoted 3 lines

With a standard GUI environment, his system would have only one interface left: the GPU one and everything should work. But of course, that may not be his config.

Well, do we need to revert 751109aad583 too, then?

No, just no, clearly using the acpi video interface for backlight control is the wrong thing to do on win8 generation laptops, if we don't flip the default we're going to end up with a never ending list of quirks for models where the acpi-video interface is broken.

Quoted 2 lines · Aaron Lu

If we have to consider the following config:
1 ACPI backlight interface works(or can work with some cmdline option);

And the BIOS advertises native win8 support.

Quoted 4 lines

2 Not using a normal GUI(depends on ACPI video module to do the in
kernel backlight level change on hotkey press).
Then we will need to revert 751109aad583.

I think the combination of 1 and 2 makes the subset of users potentially affected by this so small, that we really should continue with video.use_native_backlight=1 as default, the other route adding more and more and more and more quirks is sheer madness.

Regards,

Hans

On 07/15/2014 10:05 PM, Hans de Goede wrote:

Quoted 6 lines · Aaron Lu

Quoted 3 lines

If we have to consider the following config:
1 ACPI backlight interface works(or can work with some cmdline option);

And the BIOS advertises native win8 support.

Right.
So this condition should be:
1 ACPI backlight interface works in Win8 mode;

This means, for Julian's system, the commit 751109aad583 doesn't need to be reverted as the ACPI backlight interface on his system only works when the acpi_osi="!Windows 2012" is added. In that case, the video.use_native_backlight=X doesn't make any difference anymore.

Quoted 1 line · Aaron Lu

On 07/15/2014 10:05 PM, Hans de Goede wrote:

[cut]

Quoted 11 lines

Quoted 6 lines · Aaron Lu

Quoted 3 lines

If we have to consider the following config:
1 ACPI backlight interface works(or can work with some cmdline option);

And the BIOS advertises native win8 support.

Right.
So this condition should be:
1 ACPI backlight interface works in Win8 mode;

Quoted 4 lines

This means, for Julian's system, the commit 751109aad583 doesn't need to be reverted as the ACPI backlight interface on his system only works when the acpi_osi="!Windows 2012" is added. In that case, the video.use_native_backlight=X doesn't make any difference anymore.

But Julian reports that he needs to revert that commit to make things work as before for him. What gives?

Hi,

Quoted 21 lines · Rafael J. Wysocki

Quoted 1 line · Aaron Lu

On 07/15/2014 10:05 PM, Hans de Goede wrote:

[cut]

Quoted 15 lines

Quoted 6 lines · Aaron Lu

Quoted 3 lines

If we have to consider the following config:
1 ACPI backlight interface works(or can work with some cmdline option);

And the BIOS advertises native win8 support.

Right.
So this condition should be:
1 ACPI backlight interface works in Win8 mode;

This means, for Julian's system, the commit 751109aad583 doesn't need to be reverted as the ACPI backlight interface on his system only works when the acpi_osi="!Windows 2012" is added. In that case, the video.use_native_backlight=X doesn't make any difference anymore.

Quoted 2 lines

But Julian reports that he needs to revert that commit to make things work as before for him. What gives?

Likely what is happening is that this commit is still affecting Julian because we check if the bios is advertising win8 support, not if we are advertising win8 support ourselves.

Julian, I've jumped into this thread halfway, so I'm not 100% clear on your original problem. From what I've read sofar you need acpi_osi="!Windows 2012" for backlight control to work. That in itself is a sign that things are not as they should be, and this is actually what the new default of video.use_native_backlight=1 is trying to fix.

If you boot the new kernel without acpi_osi="!Windows 2012" and without video.use_native_backlight=X (so using the new default of video.use_native_backlight=1), what does ls /sys/class/backlight say then ?

If there is a directory in there can you then cd in to that directory, and do: "cat max_brightness" and then "echo value > brightness" (the latter as root) with value being a number, once half of max_brightness, once full brightness and see if this controls your backlight brightness.

Assuming this test succeeds, is your problem resolved then? And if not what is the problem?

Quoted 24 lines · Hans de Goede

Hi,

Quoted 21 lines · Rafael J. Wysocki

Quoted 1 line · Aaron Lu

On 07/15/2014 10:05 PM, Hans de Goede wrote:

[cut]

Quoted 15 lines

Quoted 6 lines · Aaron Lu

Quoted 3 lines

If we have to consider the following config:
1 ACPI backlight interface works(or can work with some cmdline option);

And the BIOS advertises native win8 support.

Right.
So this condition should be:
1 ACPI backlight interface works in Win8 mode;

This means, for Julian's system, the commit 751109aad583 doesn't need to be reverted as the ACPI backlight interface on his system only works when the acpi_osi="!Windows 2012" is added. In that case, the video.use_native_backlight=X doesn't make any difference anymore.

Quoted 6 lines

Quoted 2 lines

But Julian reports that he needs to revert that commit to make things work as before for him. What gives?

Likely what is happening is that this commit is still affecting Julian because we check if the bios is advertising win8 support, not if we are advertising win8 support ourselves.

Perhaps the firmware on Julian's laptop has _OSI("Windows 2013") and if that is the case, the acpi_gbl_osi_data will still get the value of ACPI_OSI_WIN_8 and acpi_osi_is_win8() will return true...

Julian,
Please attach your acpidump, thanks.

Quoted 16 lines

Julian, I've jumped into this thread halfway, so I'm not 100% clear on your original problem. From what I've read sofar you need acpi_osi="!Windows 2012" for backlight control to work. That in itself is a sign that things are not as they should be, and this is actually what the new default of video.use_native_backlight=1 is trying to fix.

If you boot the new kernel without acpi_osi="!Windows 2012" and without video.use_native_backlight=X (so using the new default of video.use_native_backlight=1), what does ls /sys/class/backlight say then ?

If there is a directory in there can you then cd in to that directory, and do: "cat max_brightness" and then "echo value > brightness" (the latter as root) with value being a number, once half of max_brightness, once full brightness and see if this controls your backlight brightness.

Quoted 2 lines

Assuming this test succeeds, is your problem resolved then? And if not what is the problem?

The problem is Julian is using a lightweight GUI that do not respond to backlight hotkey events. So he needs the in kernel processing of backlight events and for that to work, he has to add the acpi_osi="!Windows 2012" cmdline option.

Hi,

Quoted 55 lines · Aaron Lu

Quoted 24 lines · Hans de Goede

Hi,

Quoted 21 lines · Rafael J. Wysocki

Quoted 1 line · Aaron Lu

On 07/15/2014 10:05 PM, Hans de Goede wrote:

[cut]

Quoted 15 lines

Quoted 6 lines · Aaron Lu

Quoted 3 lines

If we have to consider the following config:
1 ACPI backlight interface works(or can work with some cmdline option);

And the BIOS advertises native win8 support.

Right.
So this condition should be:
1 ACPI backlight interface works in Win8 mode;

This means, for Julian's system, the commit 751109aad583 doesn't need to be reverted as the ACPI backlight interface on his system only works when the acpi_osi="!Windows 2012" is added. In that case, the video.use_native_backlight=X doesn't make any difference anymore.

Quoted 6 lines

Quoted 2 lines

But Julian reports that he needs to revert that commit to make things work as before for him. What gives?

Likely what is happening is that this commit is still affecting Julian because we check if the bios is advertising win8 support, not if we are advertising win8 support ourselves.

Perhaps the firmware on Julian's laptop has _OSI("Windows 2013") and if that is the case, the acpi_gbl_osi_data will still get the value of ACPI_OSI_WIN_8 and acpi_osi_is_win8() will return true...

Julian,
Please attach your acpidump, thanks.

Quoted 16 lines

Julian, I've jumped into this thread halfway, so I'm not 100% clear on your original problem. From what I've read sofar you need acpi_osi="!Windows 2012" for backlight control to work. That in itself is a sign that things are not as they should be, and this is actually what the new default of video.use_native_backlight=1 is trying to fix.

If you boot the new kernel without acpi_osi="!Windows 2012" and without video.use_native_backlight=X (so using the new default of video.use_native_backlight=1), what does ls /sys/class/backlight say then ?

If there is a directory in there can you then cd in to that directory, and do: "cat max_brightness" and then "echo value > brightness" (the latter as root) with value being a number, once half of max_brightness, once full brightness and see if this controls your backlight brightness.

Quoted 7 lines

Quoted 2 lines

Assuming this test succeeds, is your problem resolved then? And if not what is the problem?

The problem is Julian is using a lightweight GUI that do not respond to backlight hotkey events. So he needs the in kernel processing of backlight events and for that to work, he has to add the acpi_osi="!Windows 2012" cmdline option.

I really think we don't want people like Julian to be passing acpi_osi="!Windows 2012", just so that they may get a working acpi-video backlight control (and possible a dozen of bad side-effects), just so that they can use the brightness_switch_enabled=1 key processing.

AFAIK we all agree that the best way forward with backlight control on Windows 8 laptops is not using acpi_osi="!Windows 2012", as that is a way too big hammer, instead video.use_native_backlight=1 should be used which is why we are making this the default in 3.16.

I realize that this does not fix Julian's problem. As I see it there are 2 separate problems here:

1) backlight control issues on Windows 8 laptops, this is what we are trying to solve with video.use_native_backlight=1 (and without using any acpi_osi override)

2) Some component in the stack needs to responds to backlight key-presses and actually use the backlight control to change the backlight setting, normally this is done by gnome / kde / unity / xfce, but what about users not running those? For some of those users brightness_switch_enabled=1 has been making things work for them, but that only works if acpi-video controls the backlight, which it does not do everywhere, and which we want to get away from for Windows 8 laptops since it is just too broken there.

Note that 2. is not limited to Windows 8 laptops / acpi-video in any way, we've 23 non acpi-video backlight drivers under drivers/platform/x86/ alone + the native gpu backlight drivers. So what we really need is a solution for any laptop not using acpi-video for backlight control and not running one of the big 4 desktop environments.

Note that we pretty much have the same problem for any acpi event, power button pressed, lid closed, etc. are all "key press" type events typically handles by the desktop enviroment (e.g. we don't automatically suspend on lid-close, we just tell userspace). And we already have a solution for these type of events when running a desktop environment which handles them, these get handled by acpid. So to me it seems that the obvious (and one and only right) way to fix this is to teach acpid to deal with brightness key-presses.

I'm willing to write a patch for acpid to implement this, and then Julian's setup should just work without needing any special kernel commandline options.

Julian would that be an acceptable solution for you, and would you be willing to test such a patch ?

Regards,

Hans

I realize that this does not fix Julian's problem. As I see it there are 2 separate problems here:

1) backlight control issues on Windows 8 laptops, this is what we are trying to solve with video.use_native_backlight=1 (and without using any acpi_osi override)

2) Some component in the stack needs to responds to backlight key-presses and actually use the backlight control to change the backlight setting, normally this is done by gnome / kde / unity / xfce, but what about users not running those? For some of those users brightness_switch_enabled=1 has been making things work for them, but that only works if acpi-video controls the backlight, which it does not do everywhere, and which we want to get away from for Windows 8 laptops since it is just too broken there.

Note that 2. is not limited to Windows 8 laptops / acpi-video in any way, we've 23 non acpi-video backlight drivers under drivers/platform/x86/ alone + the native gpu backlight drivers. So what we really need is a solution for any laptop not using acpi-video for backlight control and not running one of the big 4 desktop environments.

Note that we pretty much have the same problem for any acpi event, power button pressed, lid closed, etc. are all "key press" type events typically handles by the desktop enviroment (e.g. we don't automatically suspend on lid-close, we just tell userspace). And we already have a solution for these type of events when running a desktop environment which handles them, these get handled by acpid. So to me it seems that

the obvious (and one and only right) way to fix this is to teach acpid to deal with brightness key-presses.

I'm willing to write a patch for acpid to implement this, and then Julian's setup should just work without needing any special kernel commandline options.

Julian would that be an acceptable solution for you, and would you be willing to test such a patch ?

Hi,

On 07/16/2014 10:13 AM, Hans de Goede wrote:

<snip>

Quoted 23 lines

I realize that this does not fix Julian's problem. As I see it there are 2 separate problems here:

1) backlight control issues on Windows 8 laptops, this is what we are trying to solve with video.use_native_backlight=1 (and without using any acpi_osi override)

2) Some component in the stack needs to responds to backlight key-presses and actually use the backlight control to change the backlight setting, normally this is done by gnome / kde / unity / xfce, but what about users not running those? For some of those users brightness_switch_enabled=1 has been making things work for them, but that only works if acpi-video controls the backlight, which it does not do everywhere, and which we want to get away from for Windows 8 laptops since it is just too broken there.

Note that 2. is not limited to Windows 8 laptops / acpi-video in any way, we've 23 non acpi-video backlight drivers under drivers/platform/x86/ alone + the native gpu backlight drivers. So what we really need is a solution for any laptop not using acpi-video for backlight control and not running one of the big 4 desktop environments.

Quoted 7 lines

Note that we pretty much have the same problem for any acpi event, power button pressed, lid closed, etc. are all "key press" type events typically handles by the desktop enviroment (e.g. we don't automatically suspend on lid-close, we just tell userspace). And we already have a solution for these type of events when running a desktop environment which handles them, these get handled by acpid. So to me it seems that

s/handles/does not handle/ small but important typo.

Quoted 9 lines

the obvious (and one and only right) way to fix this is to teach acpid to deal with brightness key-presses.

I'm willing to write a patch for acpid to implement this, and then Julian's setup should just work without needing any special kernel commandline options.

Julian would that be an acceptable solution for you, and would you be willing to test such a patch ?

Am Wed, 16 Jul 2014 10:35:33 +0200
schrieb Hans de Goede <[email protected]>:

Quoted 42 lines

Hi,

On 07/16/2014 10:13 AM, Hans de Goede wrote:

<snip>

Quoted 23 lines

I realize that this does not fix Julian's problem. As I see it there are 2 separate problems here:

1) backlight control issues on Windows 8 laptops, this is what we are trying to solve with video.use_native_backlight=1 (and without using any acpi_osi override)

2) Some component in the stack needs to responds to backlight key-presses and actually use the backlight control to change the backlight setting, normally this is done by gnome / kde / unity / xfce, but what about users not running those? For some of those users brightness_switch_enabled=1 has been making things work for them, but that only works if acpi-video controls the backlight, which it does not do everywhere, and which we want to get away from for Windows 8 laptops since it is just too broken there.

Note that 2. is not limited to Windows 8 laptops / acpi-video in any way, we've 23 non acpi-video backlight drivers under drivers/platform/x86/ alone + the native gpu backlight drivers. So what we really need is a solution for any laptop not using acpi-video for backlight control and not running one of the big 4 desktop environments.

Quoted 7 lines

Note that we pretty much have the same problem for any acpi event, power button pressed, lid closed, etc. are all "key press" type events typically handles by the desktop enviroment (e.g. we don't automatically suspend on lid-close, we just tell userspace). And we already have a solution for these type of events when running a desktop environment which handles them, these get handled by acpid. So to me it seems that

s/handles/does not handle/ small but important typo.

Quoted 3 lines

the obvious (and one and only right) way to fix this is to teach acpid to deal with brightness key-presses.

Quoted 6 lines

Quoted 6 lines

I'm willing to write a patch for acpid to implement this, and then Julian's setup should just work without needing any special kernel commandline options.

Julian would that be an acceptable solution for you, and would you be willing to test such a patch ?

Yes, of course that would be an acceptable solution for me and yes, I would be willing to test such a patch.

Quoted 51 lines · Julian Wollrath

Quoted 38 lines

Am Mon, 14 Jul 2014 21:10:47 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 35 lines · Rafael J. Wysocki

Quoted 33 lines · Julian Wollrath

Quoted 25 lines

Am Mon, 14 Jul 2014 20:21:19 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 22 lines · Julian Wollrath

Quoted 10 lines

Hi,

Quoted 7 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video: change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

Quoted 6 lines

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

And reverting commit 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1) make that last problem go away, right?

Quoted 5 lines

Quoted 3 lines

We are going to rever commit 886129a8eebe for other reasons, so can you please revert it from 3.16-rc5 on your system and report back?

Yes, with both 751109aad583 and 886129a8eebe reverted, changing the brightness works again.

What if you revert 886129a8eebe alone?

Quoted 8 lines

Quoted 2 lines

I mean, what exactly do you need to pass to the kernel command line in that case to make brightness switching work?

I need to pass
acpi_osi="!Windows 2012" video.brightness_switch_enabled=1
video.use_native_backlight=-1

If I leave one of these parameters out, the brightness switch stops working.

With 886129a8eebe reverted you should not need
video.brightness_switch_enabled=1.

Quoted 1 line

Aaron, what do you think?

I agree.

I suppose Julian is not using an standard GUI so he needs the in kernel processing of the backlight event.

And his laptop has a broken
ACPI interface in Win8 mode, so he also needs the "!Windows 2012" option.

With a standard GUI environment, his system would have only one interface left: the GPU one and everything should work. But of course, that may not be his config.

Thanks,
Aaron

Am Mon, 14 Jul 2014 21:10:47 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 35 lines · Rafael J. Wysocki

Quoted 33 lines · Julian Wollrath

Quoted 25 lines

Am Mon, 14 Jul 2014 20:21:19 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 22 lines · Julian Wollrath

Quoted 10 lines

Hi,

Quoted 7 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video: change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

Quoted 6 lines

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

And reverting commit 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1) make that last problem go away, right?

Quoted 5 lines

Quoted 3 lines

We are going to rever commit 886129a8eebe for other reasons, so can you please revert it from 3.16-rc5 on your system and report back?

Yes, with both 751109aad583 and 886129a8eebe reverted, changing the brightness works again.

What if you revert 886129a8eebe alone?

Quoted 2 lines

I mean, what exactly do you need to pass to the kernel command line in that case to make brightness switching work?

I need to pass
acpi_osi="!Windows 2012" video.brightness_switch_enabled=1 video.use_native_backlight=-1

If I leave one of these parameters out, the brightness switch stops working.

Quoted 44 lines

Am Mon, 14 Jul 2014 21:10:47 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 30 lines · Rafael J. Wysocki

Quoted 29 lines · Julian Wollrath

Quoted 28 lines

Am Mon, 14 Jul 2014 20:21:19 +0200
schrieb "Rafael J. Wysocki" <[email protected]>:

Quoted 25 lines · Julian Wollrath

Quoted 10 lines

Hi,

Quoted 7 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video: change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

Quoted 6 lines

small correction: It setting "acpi_osi=!Windows 2012" does only help when using a kernel with commit 886129a8eebe as HEAD, with v3.16-rc4 setting video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 or just one of them, does not make changing the brightness work again.

And reverting commit 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1) make that last problem go away, right?

We are going to rever commit 886129a8eebe for other reasons, so can you please revert it from 3.16-rc5 on your system and report back?

Quoted 7 lines

Quoted 4 lines

Quoted 2 lines

Yes, with both 751109aad583 and 886129a8eebe reverted, changing the brightness works again.

What if you revert 886129a8eebe alone?

I mean, what exactly do you need to pass to the kernel command line in that case to make brightness switching work?

I need to pass
acpi_osi="!Windows 2012" video.brightness_switch_enabled=1
video.use_native_backlight=-1

Quoted 2 lines

If I leave one of these parameters out, the brightness switch stops working.

If you only pass the following 2 cmdline options:
acpi_osi="!Windows 2012" video.brightness_switch_enabled=1 Will there be the /sys/class/backlight/acpi_videoX file?

Hi,

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video: change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

With best regards,
Julian Wollrath
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Quoted 6 lines

changing the brightness on my Thinkpad X230 with Intel HD4000 graphics, stopped working after commit 886129a8eebe (ACPI / video:
change acpi-video brightness_switch_enabled default to 0). Changing it back to 1, fixes the problem, if "acpi_osi=!Windows 2012" is also set. Before that commit just setting "acpi_osi=!Windows 2012" was enough to get changing the brightness working.

Does your system have /sys/class/backlight/intel_backlight? Does it work if you manually change the brightness file like this:

# cd /sys/class/backlight/intel_backlight
# cat max_brightness
xxxxx
# echo xxx > brightness
# echo xxx > brightness
...