| Message ID | 1370818899-8595-4-git-send-email-matthew.garrett@nebula.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, Jun 09, 2013 at 07:01:39PM -0400, Matthew Garrett wrote: > Windows 8 leaves backlight control up to individual graphics drivers rather > than making ACPI calls itself. There's plenty of evidence to suggest that > the Intel driver for Windows doesn't use the ACPI interface, including the > fact that it's broken on a bunch of machines when the OS claims to support > Windows 8. The simplest thing to do appears to be to disable the ACPI > backlight interface on these systems. > > Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> Make sense and I guess it's easier to merge this all through the acpi tree. So Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> > --- > drivers/gpu/drm/i915/i915_dma.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c > index 3b315ba..23b6292 100644 > --- a/drivers/gpu/drm/i915/i915_dma.c > +++ b/drivers/gpu/drm/i915/i915_dma.c > @@ -1661,6 +1661,9 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags) > /* Must be done after probing outputs */ > intel_opregion_init(dev); > acpi_video_register(); > + /* Don't use ACPI backlight functions on Windows 8 platforms */ > + if (acpi_osi_version() >= ACPI_OSI_WIN_8) > + acpi_video_backlight_unregister(); > } > > if (IS_GEN5(dev)) > -- > 1.8.2.1 >
? ??2013-06-09 ? 19:01 -0400?Matthew Garrett ??? > Windows 8 leaves backlight control up to individual graphics drivers rather > than making ACPI calls itself. There's plenty of evidence to suggest that > the Intel driver for Windows doesn't use the ACPI interface, including the > fact that it's broken on a bunch of machines when the OS claims to support > Windows 8. The simplest thing to do appears to be to disable the ACPI > backlight interface on these systems. > > Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> > --- > drivers/gpu/drm/i915/i915_dma.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c > index 3b315ba..23b6292 100644 > --- a/drivers/gpu/drm/i915/i915_dma.c > +++ b/drivers/gpu/drm/i915/i915_dma.c > @@ -1661,6 +1661,9 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags) > /* Must be done after probing outputs */ > intel_opregion_init(dev); > acpi_video_register(); > + /* Don't use ACPI backlight functions on Windows 8 platforms */ > + if (acpi_osi_version() >= ACPI_OSI_WIN_8) > + acpi_video_backlight_unregister(); > } > > if (IS_GEN5(dev)) This patch set works to me on Acer Aspire V3 notebook for unregister the backlight interface of acpi video driver when i915 loaded. Acer Aspire V3 has the Windows8 support in DSDT. Tested-by: Lee, Chun-Yi <jlee@suse.com> Thanks a lot! Joey Lee
On 06/10/2013 07:01 AM, Matthew Garrett wrote: > Windows 8 leaves backlight control up to individual graphics drivers rather > than making ACPI calls itself. There's plenty of evidence to suggest that > the Intel driver for Windows doesn't use the ACPI interface, including the > fact that it's broken on a bunch of machines when the OS claims to support > Windows 8. The simplest thing to do appears to be to disable the ACPI > backlight interface on these systems. > > Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> > --- > drivers/gpu/drm/i915/i915_dma.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c > index 3b315ba..23b6292 100644 > --- a/drivers/gpu/drm/i915/i915_dma.c > +++ b/drivers/gpu/drm/i915/i915_dma.c > @@ -1661,6 +1661,9 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags) > /* Must be done after probing outputs */ > intel_opregion_init(dev); > acpi_video_register(); > + /* Don't use ACPI backlight functions on Windows 8 platforms */ > + if (acpi_osi_version() >= ACPI_OSI_WIN_8) > + acpi_video_backlight_unregister(); What about the platform driver created backlight interface? Oh right, thinkpad_acpi will not create backlight interface for them since they are not in DMI table, so acpi_video_backlight_support() will return true and thinkspad_acpi thinks ACPI video driver is controlling backlight so it will not create backlight interface for them. Then we will need to remember not to add any of those systems into the DMI table of video_detect.c, or thinkpad_acpi module will create backlight interface for them and according to reporter, that interface does not work either. What about a priority based solution? We can introduce a new field named priority to backlight_device and instead of calling another module's function like the unregister one here(which cause unnecessary module dependency), we only need to boost priority for its own interface. This field will be exported to sysfs, so user can change it during runtime too. And we can also introduce a new kernel command line as backlight.force_interface=raw/firmware/platform, to overcome the limited functionality provided by acpi_backlight=video/vendor, which does not involve GPU's interface. And we can place the quirk code in backlight layer instead of individual backlight functionality provider module. Suppose we have a backlight manager there, for all win8 systems, we can boost the raw type's priority on its registration, so no need to add code in intel/amd/etc./'s GPU driver code. With priority based solution, all backlight control interfaces stay, the priority field is an indication given by kernel to user space. For a complete description on backlight control background and the proposed solution, please take a look at: https://gist.github.com/aaronlu/5779828 It would be good to know your opinions, thanks. -Aaron
On Fri, 2013-06-14 at 14:47 +0800, Aaron Lu wrote: > What about a priority based solution? We can introduce a new field named > priority to backlight_device and instead of calling another module's > function like the unregister one here(which cause unnecessary module > dependency), we only need to boost priority for its own interface. This > field will be exported to sysfs, so user can change it during runtime > too. And we can also introduce a new kernel command line as > backlight.force_interface=raw/firmware/platform, to overcome the limited > functionality provided by acpi_backlight=video/vendor, which does not > involve GPU's interface. How would that work with existing userspace? > And we can place the quirk code in backlight layer instead of individual > backlight functionality provider module. Suppose we have a backlight > manager there, for all win8 systems, we can boost the raw type's > priority on its registration, so no need to add code in > intel/amd/etc./'s GPU driver code. But we'd need to add code to every piece of userspace that currently uses the backlight, right? > With priority based solution, all backlight control interfaces stay, > the priority field is an indication given by kernel to user space. We shouldn't export interfaces if we don't expect them to work.
On 06/15/2013 01:29 AM, Matthew Garrett wrote: > On Fri, 2013-06-14 at 14:47 +0800, Aaron Lu wrote: > >> What about a priority based solution? We can introduce a new field named >> priority to backlight_device and instead of calling another module's >> function like the unregister one here(which cause unnecessary module >> dependency), we only need to boost priority for its own interface. This >> field will be exported to sysfs, so user can change it during runtime >> too. And we can also introduce a new kernel command line as >> backlight.force_interface=raw/firmware/platform, to overcome the limited >> functionality provided by acpi_backlight=video/vendor, which does not >> involve GPU's interface. > > How would that work with existing userspace? User space tool will need to be updated to use this as stated in the gist page, I've patches for gsd-backlight-helper and xorg-x11-drv-intel, for others we can add I think if the priority based solution is deemed useful. > >> And we can place the quirk code in backlight layer instead of individual >> backlight functionality provider module. Suppose we have a backlight >> manager there, for all win8 systems, we can boost the raw type's >> priority on its registration, so no need to add code in >> intel/amd/etc./'s GPU driver code. > > But we'd need to add code to every piece of userspace that currently > uses the backlight, right? Yes that's the case. > >> With priority based solution, all backlight control interfaces stay, >> the priority field is an indication given by kernel to user space. > > We shouldn't export interfaces if we don't expect them to work. It's not easy to decide if they work or not sometimes, e.g. I came across a system that claims win8 in ACPI table and has an Intel GPU, while its ACPI video interface also works. With this patch, the working ACPI video interface is removed, while with the priority based solution, the GPU's interface priority gets higher, but the ACPI video interface still stays. Thanks, Aaron
On Sat, 2013-06-15 at 09:26 +0800, Aaron Lu wrote: > On 06/15/2013 01:29 AM, Matthew Garrett wrote: > > How would that work with existing userspace? > > User space tool will need to be updated to use this as stated in the > gist page, I've patches for gsd-backlight-helper and xorg-x11-drv-intel, > for others we can add I think if the priority based solution is deemed > useful. Right, that's not a great solution. > > We shouldn't export interfaces if we don't expect them to work. > > It's not easy to decide if they work or not sometimes, e.g. I came > across a system that claims win8 in ACPI table and has an Intel GPU, > while its ACPI video interface also works. With this patch, the working > ACPI video interface is removed, while with the priority based solution, > the GPU's interface priority gets higher, but the ACPI video interface > still stays. Well, Windows 8 will only use the ACPI backlight interface if the GPU driver decides to, right? So the logic for deciding whether to remove the ACPI backlight control or not should be left up to the GPU. There's no harm in refusing to expose a working method if there's another working method, but there is harm in exposing a broken one and expecting userspace to know the difference.
On 06/15/2013 09:38 AM, Matthew Garrett wrote: > On Sat, 2013-06-15 at 09:26 +0800, Aaron Lu wrote: >> It's not easy to decide if they work or not sometimes, e.g. I came >> across a system that claims win8 in ACPI table and has an Intel GPU, >> while its ACPI video interface also works. With this patch, the working >> ACPI video interface is removed, while with the priority based solution, >> the GPU's interface priority gets higher, but the ACPI video interface >> still stays. > > Well, Windows 8 will only use the ACPI backlight interface if the GPU > driver decides to, right? So the logic for deciding whether to remove > the ACPI backlight control or not should be left up to the GPU. There's I don't know this. From the document I googled, Microsoft suggests under win8, backlight should be controlled by the graphics driver for smooth brightness level change, instead of ACPI or other methods. So it is possible that OEM will not test the ACPI interface well and thus the interface is likely broken. I don't see why GPU driver has any better knowledge on which systems the firmware interface is broken or not. > no harm in refusing to expose a working method if there's another > working method, but there is harm in exposing a broken one and expecting > userspace to know the difference. BTW, the proposed solution is not meant to solve win8 problems alone, it should make solving other problems easy and make individual backlight control interface provider module independent with each other such as the platform drivers will not need to check if ACPI video driver will control backlight or not and can always create backlight interface(its default priority is lower that ACPI video driver's so will not be taken by user space by default, showing the same behavior of the current code). The current acpi_backlight=video/vendor kernel command line is pretty misleading, for laptops that do not have vendor backlight interface, adding acpi_backlight=vendor actually makes the system using the GPU's interface. Some laptops are using this switch to work around problems in ACPI video driver and users think they are using vendor interface. That's why I think we need a new command line as the backlight.force_interface=raw/firmware/platform. Instead of letting individual driver to make decisions on which backlight interface this system should use(either in platform driver as we currently did, see acer-wmi and asus-wmi, or GPU driver as this case), I think we need a better and clear way to handle such things. For example, suppose an acer laptop: vendor does not support backlight, ACPI video's backlight interface is broken and GPU's works, to make it work, user will need to select acer-wmi module while this module does not have anything to do with the functionality, but simply because it serves as the backlight manager for acer laptops. The above information and idea is formed while solving bugs reported in kernel bugzilla video component, the proposed solutin may not be good enough, but I hope we can find a better way to handle backlight problems. Thanks, Aaron
On Sat, Jun 15, 2013 at 12:14:42PM +0800, Aaron Lu wrote: > On 06/15/2013 09:38 AM, Matthew Garrett wrote: > > Well, Windows 8 will only use the ACPI backlight interface if the GPU > > driver decides to, right? So the logic for deciding whether to remove > > the ACPI backlight control or not should be left up to the GPU. There's > > I don't know this. From the document I googled, Microsoft suggests under > win8, backlight should be controlled by the graphics driver for smooth > brightness level change, instead of ACPI or other methods. So it is > possible that OEM will not test the ACPI interface well and thus the > interface is likely broken. I don't see why GPU driver has any better > knowledge on which systems the firmware interface is broken or not. The vendor will presumably have tested that backlight control works - if the GPU driver uses the ACPI interface and backlight control is broken, then the vendor would fix it. > > no harm in refusing to expose a working method if there's another > > working method, but there is harm in exposing a broken one and expecting > > userspace to know the difference. > > BTW, the proposed solution is not meant to solve win8 problems alone, it > should make solving other problems easy and make individual backlight > control interface provider module independent with each other such as > the platform drivers will not need to check if ACPI video driver will > control backlight or not and can always create backlight interface(its > default priority is lower that ACPI video driver's so will not be taken > by user space by default, showing the same behavior of the current code). Sure, but it still requires the replacement of existing userspace. We need to fix the problem with existing userspace, too. > The current acpi_backlight=video/vendor kernel command line is pretty > misleading, for laptops that do not have vendor backlight interface, > adding acpi_backlight=vendor actually makes the system using the GPU's > interface. Some laptops are using this switch to work around problems in > ACPI video driver and users think they are using vendor interface. > That's why I think we need a new command line as the > backlight.force_interface=raw/firmware/platform. No, I think we need to fix the bugs that currently require users to pass options. > Instead of letting individual driver to make decisions on which > backlight interface this system should use(either in platform driver as > we currently did, see acer-wmi and asus-wmi, or GPU driver as this case), > I think we need a better and clear way to handle such things. For > example, suppose an acer laptop: vendor does not support backlight, ACPI > video's backlight interface is broken and GPU's works, to make it work, > user will need to select acer-wmi module while this module does not have > anything to do with the functionality, but simply because it serves as > the backlight manager for acer laptops. How do these machines work under Windows? Until we know the answer to that, we don't know what the correct way to handle the problem is under Linux.
On 06/15/2013 12:19 PM, Matthew Garrett wrote: > On Sat, Jun 15, 2013 at 12:14:42PM +0800, Aaron Lu wrote: >> On 06/15/2013 09:38 AM, Matthew Garrett wrote: >>> Well, Windows 8 will only use the ACPI backlight interface if the GPU >>> driver decides to, right? So the logic for deciding whether to remove >>> the ACPI backlight control or not should be left up to the GPU. There's >> >> I don't know this. From the document I googled, Microsoft suggests under >> win8, backlight should be controlled by the graphics driver for smooth >> brightness level change, instead of ACPI or other methods. So it is >> possible that OEM will not test the ACPI interface well and thus the >> interface is likely broken. I don't see why GPU driver has any better >> knowledge on which systems the firmware interface is broken or not. > > The vendor will presumably have tested that backlight control works - if > the GPU driver uses the ACPI interface and backlight control is broken, > then the vendor would fix it. I don't think GPU driver uses ACPI interface, that's why for some systems, ACPI interface is broken while the GPU's is not. > >>> no harm in refusing to expose a working method if there's another >>> working method, but there is harm in exposing a broken one and expecting >>> userspace to know the difference. >> >> BTW, the proposed solution is not meant to solve win8 problems alone, it >> should make solving other problems easy and make individual backlight >> control interface provider module independent with each other such as >> the platform drivers will not need to check if ACPI video driver will >> control backlight or not and can always create backlight interface(its >> default priority is lower that ACPI video driver's so will not be taken >> by user space by default, showing the same behavior of the current code). > > Sure, but it still requires the replacement of existing userspace. We > need to fix the problem with existing userspace, too. Yes. The problem is two way. First, some of the backlight interface privoder module provides a broken interface; Two, the userspace picked a broken interface while there are usable ones. For example, in the win8 thinkpad case, the ACPI video driver provides broken interface and the GPU driver provides usable interface, but userspace choose ACPI video's interface. To make things complicated, if we make the broken interface disappear in ACPI video module, then the platform driver thinkpad_acpi will start to provide another broken interface. I have to say, solve it in the GPU code is a clever way, it's just a little weird to me for a broken interface to be blacklisted, we have to do it in another module, not the broken module itself. > >> The current acpi_backlight=video/vendor kernel command line is pretty >> misleading, for laptops that do not have vendor backlight interface, >> adding acpi_backlight=vendor actually makes the system using the GPU's >> interface. Some laptops are using this switch to work around problems in >> ACPI video driver and users think they are using vendor interface. >> That's why I think we need a new command line as the >> backlight.force_interface=raw/firmware/platform. > > No, I think we need to fix the bugs that currently require users to pass > options. For ACPI video driver, since it relies on firmware to do the right thing, if the functionality is broken, then it is, there is hardly anything we can do...(not always, we can quirk in some cases, but there are cases we can do nothing). In this case, we can: 1 Ask user to add acpi_backlight=vendor, so that ACPI video driver will not create backlight interface and userspace will not pick it; 2 Add that model in DMI table in video_detect.c, eliminating the need for that command line; 3 Add that model in DMI table in another module, let that module unregister backlight interface provided by ACPI video as is done in acer-wmi, asus-wmi, and i915 in this case; 3 Use the backlight section in xorg.conf to make X uses another backlight interface. This may not work for distros that use gsd-backlight-helper, which always prefers firmware. Which one do you prefer? > >> Instead of letting individual driver to make decisions on which >> backlight interface this system should use(either in platform driver as >> we currently did, see acer-wmi and asus-wmi, or GPU driver as this case), >> I think we need a better and clear way to handle such things. For >> example, suppose an acer laptop: vendor does not support backlight, ACPI >> video's backlight interface is broken and GPU's works, to make it work, >> user will need to select acer-wmi module while this module does not have >> anything to do with the functionality, but simply because it serves as >> the backlight manager for acer laptops. > > How do these machines work under Windows? Until we know the answer to > that, we don't know what the correct way to handle the problem is under > Linux. Do you mean we need to understand Windows behavior so that we can decide where to place the code to do the backlight management thing? So for win8 case, we know MS will use GPU driver to do backlight control, all this means to me is, ACPI video's and platform driver's interface are more likely broken on those systems, but it doesn't qualify why Linux' GPU driver should do the decision, it's not that the GPU driver can poke some GPU register and then decide oh, this model does not have working ACPI backlight interface. As this patch shows, we make the decision by OSI, which is not specific to GPU driver. BTW, I don't think any module knows something better than another module, all quirk logic and DMI entry we currently have in Linux are got by user's feedback(bug reports), it doesn't seem to me some module is natrually the one that should make this decision. Or do I miss something? Thanks, Aaron
On Sat, Jun 15, 2013 at 08:29:15PM +0800, Aaron Lu wrote: > On 06/15/2013 12:19 PM, Matthew Garrett wrote: > > The vendor will presumably have tested that backlight control works - if > > the GPU driver uses the ACPI interface and backlight control is broken, > > then the vendor would fix it. > > I don't think GPU driver uses ACPI interface, that's why for some > systems, ACPI interface is broken while the GPU's is not. On systems where the ACPI interface is broken, the GPU driver clearly doesn't use the ACPI interface. As yet, we don't know if that's always true, though. > > Sure, but it still requires the replacement of existing userspace. We > > need to fix the problem with existing userspace, too. > > Yes. The problem is two way. First, some of the backlight interface > privoder module provides a broken interface; Two, the userspace picked a > broken interface while there are usable ones. For example, in the win8 > thinkpad case, the ACPI video driver provides broken interface and the > GPU driver provides usable interface, but userspace choose ACPI video's > interface. To make things complicated, if we make the broken interface > disappear in ACPI video module, then the platform driver thinkpad_acpi > will start to provide another broken interface. I have to say, solve it > in the GPU code is a clever way, it's just a little weird to me for a > broken interface to be blacklisted, we have to do it in another module, > not the broken module itself. The ACPI driver has no way of making this kind of policy decision. The GPU driver does. > > No, I think we need to fix the bugs that currently require users to pass > > options. > > For ACPI video driver, since it relies on firmware to do the right thing, > if the functionality is broken, then it is, there is hardly anything we > can do...(not always, we can quirk in some cases, but there are cases we > can do nothing). In this case, we can: > 1 Ask user to add acpi_backlight=vendor, so that ACPI video driver will > not create backlight interface and userspace will not pick it; > 2 Add that model in DMI table in video_detect.c, eliminating the need for > that command line; > 3 Add that model in DMI table in another module, let that module > unregister backlight interface provided by ACPI video as is done in > acer-wmi, asus-wmi, and i915 in this case; > 3 Use the backlight section in xorg.conf to make X uses another > backlight interface. This may not work for distros that use > gsd-backlight-helper, which always prefers firmware. > > Which one do you prefer? I'd prefer to figure out how it works in Windows and implement it the same way. > > How do these machines work under Windows? Until we know the answer to > > that, we don't know what the correct way to handle the problem is under > > Linux. > > Do you mean we need to understand Windows behavior so that we can > decide where to place the code to do the backlight management thing? > So for win8 case, we know MS will use GPU driver to do backlight > control, all this means to me is, ACPI video's and platform driver's > interface are more likely broken on those systems, but it doesn't > qualify why Linux' GPU driver should do the decision, it's not that the > GPU driver can poke some GPU register and then decide oh, this model > does not have working ACPI backlight interface. As this patch shows, we > make the decision by OSI, which is not specific to GPU driver. Sure it is - for all we know there's a value in the opregion space that tells the Intel GPU driver which interface we should be using. We don't know because Intel haven't released a version of the opregion driver newer than 2007. It may be that all Windows 8 GPU drivers use the GPU backlight control registers directly and never use any firmware interface, but right now we simply don't know that. All we can do is look at the existing cases we have and say that it appears that Intel graphics systems don't use the ACPI interface. Anything more than that requires more evidence. > BTW, I don't think any module knows something better than another > module, all quirk logic and DMI entry we currently have in Linux are > got by user's feedback(bug reports), it doesn't seem to me some module > is natrually the one that should make this decision. Or do I miss > something? The GPU driver makes the policy decision under Windows 8, so it's the natural place to make this decision on Windows 8 systems.
Hi all,
So to me it looks like the discussion is going in circles a bit, hence let
me drop my maintainer-opinion here:
1. Matthew's patch series here looks reasonable, and if it fixes a bunch
of systems (which it seems to) it has my Ack and imo should go in. If acpi
maintainers can smash their Ack onto the acpi parts I'd very much like to
merge this into drm-intel-next, that should give us the most coverage for
intel systems.
Len, Rafael, are you ok with the acpi part of this and merging it through
drm-intel-next?
2. Imo the current amount of quirking we expose to users (we have kernel
options to disable the acpi interface, blacklist platform modules, all
backlights can be tested through sysfs and on top of that xf86-video-intel
has an xorg.conf to select the backlight used by the driver). I haven't
spotted a compelling reason in this thread to add another one, what we
have seems to be good enough to debug backligh issues.
3. Also, adding yet another backlight quirk mechanism isn't gonna
magically fix broken systems.
We _really_ should strive to make this just work and not offer the angry
user another roll of duct-tape for free.
4. The currently established priority selection for backlights of platform
> firmware > raw seems to be good enough. Note that the explicit list in
xf86-vidoe-intel is only used as a fallback for really old kernels which
do not expose this information. We could probably rip it out.
5. We've recently looked at opregion again and couldn't spot a hint.
Unfortnately it looks like both noodling better information out of Intel
and trying to publish an updated opregion spec seem to be losing games :(
We'll keep on trying though.
Aside at the end: If the gnome tool indeed has its own backlight code and
doesn't just use that as a fallback if the xrandr backligh property isn't
available, then that's just a serious bug in gnome and should be fixed
asap. But imo that's not something we should try to (nor do I see any way
how to) work around in the kernel.
Cheers, Daniel
On Sat, Jun 15, 2013 at 08:29:42PM +0200, Daniel Vetter wrote: > Aside at the end: If the gnome tool indeed has its own backlight code and > doesn't just use that as a fallback if the xrandr backligh property isn't > available, then that's just a serious bug in gnome and should be fixed > asap. But imo that's not something we should try to (nor do I see any way > how to) work around in the kernel. It's only used if there's no backlight property on the display.
On Saturday, June 15, 2013 08:29:42 PM Daniel Vetter wrote: > Hi all, > > So to me it looks like the discussion is going in circles a bit, hence let > me drop my maintainer-opinion here: > > 1. Matthew's patch series here looks reasonable, and if it fixes a bunch > of systems (which it seems to) it has my Ack and imo should go in. If acpi > maintainers can smash their Ack onto the acpi parts I'd very much like to > merge this into drm-intel-next, that should give us the most coverage for > intel systems. > > Len, Rafael, are you ok with the acpi part of this and merging it through > drm-intel-next? It has to go through the ACPI tree because of the ACPICA patch that needs to be synchronized with the ACPICA upstream. Sorry. That said, I'm going to take this patchset. > 2. Imo the current amount of quirking we expose to users (we have kernel > options to disable the acpi interface, blacklist platform modules, all > backlights can be tested through sysfs and on top of that xf86-video-intel > has an xorg.conf to select the backlight used by the driver). I haven't > spotted a compelling reason in this thread to add another one, what we > have seems to be good enough to debug backligh issues. > > 3. Also, adding yet another backlight quirk mechanism isn't gonna > magically fix broken systems. > > We _really_ should strive to make this just work and not offer the angry > user another roll of duct-tape for free. > > 4. The currently established priority selection for backlights of platform > > firmware > raw seems to be good enough. Note that the explicit list in > xf86-vidoe-intel is only used as a fallback for really old kernels which > do not expose this information. We could probably rip it out. > > 5. We've recently looked at opregion again and couldn't spot a hint. > Unfortnately it looks like both noodling better information out of Intel > and trying to publish an updated opregion spec seem to be losing games :( > We'll keep on trying though. > > Aside at the end: If the gnome tool indeed has its own backlight code and > doesn't just use that as a fallback if the xrandr backligh property isn't > available, then that's just a serious bug in gnome and should be fixed > asap. But imo that's not something we should try to (nor do I see any way > how to) work around in the kernel. Agreed. Thanks, Rafael
On Sat, Jun 15, 2013 at 10:27:06PM +0200, Rafael J. Wysocki wrote: > On Saturday, June 15, 2013 08:29:42 PM Daniel Vetter wrote: > > Hi all, > > > > So to me it looks like the discussion is going in circles a bit, hence let > > me drop my maintainer-opinion here: > > > > 1. Matthew's patch series here looks reasonable, and if it fixes a bunch > > of systems (which it seems to) it has my Ack and imo should go in. If acpi > > maintainers can smash their Ack onto the acpi parts I'd very much like to > > merge this into drm-intel-next, that should give us the most coverage for > > intel systems. > > > > Len, Rafael, are you ok with the acpi part of this and merging it through > > drm-intel-next? > > It has to go through the ACPI tree because of the ACPICA patch that needs to > be synchronized with the ACPICA upstream. Sorry. No problem, since we're pretty close to the merge window that would have at most resulted in a few more weeks of testing in i915 trees anyway. -rc kernels should still give us plenty of time to catch fallout, if there is any. > That said, I'm going to take this patchset. Thanks, Daniel
On Sunday, June 09, 2013 07:01:39 PM Matthew Garrett wrote: > Windows 8 leaves backlight control up to individual graphics drivers rather > than making ACPI calls itself. There's plenty of evidence to suggest that > the Intel driver for Windows doesn't use the ACPI interface, including the > fact that it's broken on a bunch of machines when the OS claims to support > Windows 8. The simplest thing to do appears to be to disable the ACPI > backlight interface on these systems. > > Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> > --- > drivers/gpu/drm/i915/i915_dma.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c > index 3b315ba..23b6292 100644 > --- a/drivers/gpu/drm/i915/i915_dma.c > +++ b/drivers/gpu/drm/i915/i915_dma.c > @@ -1661,6 +1661,9 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags) > /* Must be done after probing outputs */ > intel_opregion_init(dev); > acpi_video_register(); > + /* Don't use ACPI backlight functions on Windows 8 platforms */ > + if (acpi_osi_version() >= ACPI_OSI_WIN_8) > + acpi_video_backlight_unregister(); > } > > if (IS_GEN5(dev)) > Well, this causes build failures to happen when the ACPI video driver is modular and the graphics driver is not. I'm not sure how to resolve that, so suggestions are welcome. Thanks, Rafael
On Friday, July 05, 2013 02:20:14 PM Rafael J. Wysocki wrote: > On Sunday, June 09, 2013 07:01:39 PM Matthew Garrett wrote: > > Windows 8 leaves backlight control up to individual graphics drivers rather > > than making ACPI calls itself. There's plenty of evidence to suggest that > > the Intel driver for Windows doesn't use the ACPI interface, including the > > fact that it's broken on a bunch of machines when the OS claims to support > > Windows 8. The simplest thing to do appears to be to disable the ACPI > > backlight interface on these systems. > > > > Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> > > --- > > drivers/gpu/drm/i915/i915_dma.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c > > index 3b315ba..23b6292 100644 > > --- a/drivers/gpu/drm/i915/i915_dma.c > > +++ b/drivers/gpu/drm/i915/i915_dma.c > > @@ -1661,6 +1661,9 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags) > > /* Must be done after probing outputs */ > > intel_opregion_init(dev); > > acpi_video_register(); > > + /* Don't use ACPI backlight functions on Windows 8 platforms */ > > + if (acpi_osi_version() >= ACPI_OSI_WIN_8) > > + acpi_video_backlight_unregister(); > > } > > > > if (IS_GEN5(dev)) > > > > Well, this causes build failures to happen when the ACPI video driver is > modular and the graphics driver is not. > > I'm not sure how to resolve that, so suggestions are welcome. Actually, that happened with the radeon patch. That said, ACPI_OSI_WIN_8 doesn't make much sense for !CONFIG_ACPI, for example. What about making acpi_video_register() do the quirk instead? We could add an argument to it indicating whether or not quirks should be applied. Thanks, Rafael
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c index 3b315ba..23b6292 100644 --- a/drivers/gpu/drm/i915/i915_dma.c +++ b/drivers/gpu/drm/i915/i915_dma.c @@ -1661,6 +1661,9 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags) /* Must be done after probing outputs */ intel_opregion_init(dev); acpi_video_register(); + /* Don't use ACPI backlight functions on Windows 8 platforms */ + if (acpi_osi_version() >= ACPI_OSI_WIN_8) + acpi_video_backlight_unregister(); } if (IS_GEN5(dev))
Windows 8 leaves backlight control up to individual graphics drivers rather than making ACPI calls itself. There's plenty of evidence to suggest that the Intel driver for Windows doesn't use the ACPI interface, including the fact that it's broken on a bunch of machines when the OS claims to support Windows 8. The simplest thing to do appears to be to disable the ACPI backlight interface on these systems. Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> --- drivers/gpu/drm/i915/i915_dma.c | 3 +++ 1 file changed, 3 insertions(+)