From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: Re: ACPI/i915: Cannot configure display brightness on Dell Latitude E6440 Date: Wed, 24 Sep 2014 16:34:21 +0200 Message-ID: <5422D66D.6090903@redhat.com> References: <201409232206.02819@pali> <201409241114.11604@pali> <5422B354.4010005@redhat.com> <201409241453.46756@pali> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <201409241453.46756@pali> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: =?UTF-8?B?UGFsaSBSb2jDoXI=?= Cc: Aaron Lu , David Airlie , Daniel Vetter , intel-gfx@lists.freedesktop.org, "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, dri-devel@lists.freedesktop.org, Zhang Rui , Len Brown List-Id: linux-acpi@vger.kernel.org SGksCgpPbiAwOS8yNC8yMDE0IDAyOjUzIFBNLCBQYWxpIFJvaMOhciB3cm90ZToKPiBPbiBXZWRu ZXNkYXkgMjQgU2VwdGVtYmVyIDIwMTQgMTQ6MDQ6MzYgSGFucyBkZSBHb2VkZSB3cm90ZToKPj4g SGksCj4+Cj4+IE9uIDA5LzI0LzIwMTQgMTE6MTQgQU0sIFBhbGkgUm9ow6FyIHdyb3RlOgo+Pj4g T24gV2VkbmVzZGF5IDI0IFNlcHRlbWJlciAyMDE0IDEwOjU5OjQxIFBhbGkgUm9ow6FyIHdyb3Rl Ogo+Pj4+IE9uIFdlZG5lc2RheSAyNCBTZXB0ZW1iZXIgMjAxNCAxMDoxOTozOCBIYW5zIGRlIEdv ZWRlIHdyb3RlOgo+Pj4+PiBIaSwKPj4+Pj4KPj4+Pj4gT24gMDkvMjMvMjAxNCAxMDo0NCBQTSwg UGFsaSBSb2jDoXIgd3JvdGU6Cj4+Pj4+PiBPbiBUdWVzZGF5IDIzIFNlcHRlbWJlciAyMDE0IDIy OjMxOjMxIHlvdSB3cm90ZToKPj4+Pj4+PiBIaSwKPj4+Pj4+Pgo+Pj4+Pj4+IE9uIDA5LzIzLzIw MTQgMTA6MDYgUE0sIFBhbGkgUm9ow6FyIHdyb3RlOgo+Pj4+Pj4+PiBIZWxsbywKPj4+Pj4+Pj4K Pj4+Pj4+Pj4gYWZ0ZXIgYmlnIGNoYW5nZXMgaW4gYWNwaSB2aWRlby9pOTE1IGNvZGUgSSBjYW5u 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d2UgZG8gaWYgeW91IGRvbid0IHNwZWNpZnkgYW55IGtlcm5lbApjb21tYW5kbGluZSBwYXJhbWV0 ZXJzLCBjYXNlIGNsb3NlZC4KClJlZ2FyZHMsCgpIYW5zCl9fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fCkludGVsLWdmeCBtYWlsaW5nIGxpc3QKSW50ZWwtZ2Z4 QGxpc3RzLmZyZWVkZXNrdG9wLm9yZwpodHRwOi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxt YW4vbGlzdGluZm8vaW50ZWwtZ2Z4Cg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753320AbaIXOej (ORCPT ); Wed, 24 Sep 2014 10:34:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55538 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752888AbaIXOeg (ORCPT ); Wed, 24 Sep 2014 10:34:36 -0400 Message-ID: <5422D66D.6090903@redhat.com> Date: Wed, 24 Sep 2014 16:34:21 +0200 From: Hans de Goede User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: =?UTF-8?B?UGFsaSBSb2jDoXI=?= CC: "Rafael J. Wysocki" , Zhang Rui , Len Brown , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, Aaron Lu , Daniel Vetter , Jani Nikula , David Airlie , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Subject: Re: ACPI/i915: Cannot configure display brightness on Dell Latitude E6440 References: <201409232206.02819@pali> <201409241114.11604@pali> <5422B354.4010005@redhat.com> <201409241453.46756@pali> In-Reply-To: <201409241453.46756@pali> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 09/24/2014 02:53 PM, Pali Rohár wrote: > On Wednesday 24 September 2014 14:04:36 Hans de Goede wrote: >> Hi, >> >> On 09/24/2014 11:14 AM, Pali Rohár wrote: >>> On Wednesday 24 September 2014 10:59:41 Pali Rohár wrote: >>>> On Wednesday 24 September 2014 10:19:38 Hans de Goede wrote: >>>>> Hi, >>>>> >>>>> On 09/23/2014 10:44 PM, Pali Rohár wrote: >>>>>> On Tuesday 23 September 2014 22:31:31 you wrote: >>>>>>> Hi, >>>>>>> >>>>>>> On 09/23/2014 10:06 PM, Pali Rohár wrote: >>>>>>>> Hello, >>>>>>>> >>>>>>>> after big changes in acpi video/i915 code I cannot >>>>>>>> change display brightness on my Dell Latitude E6440 >>>>>>>> with kernel 3.17-rc6. With kernel 3.13 everything >>>>>>>> worked fine. >>>>>>>> >>>>>>>> More information about this problem: >>>>>>>> >>>>>>>> For configuring brightness on Dell laptops there are 4 >>>>>>>> ways: 1) via acpi video driver >>>>>>>> 2) via dell-laptop driver >>>>>>>> 3) via i915 drm driver >>>>>>>> 4) from userspace with special dell SMI call >>>>>>>> >>>>>>>> (e.g with program dellLcdBrightness from libsmbios >>>>>>>> package) >>>>>>>> >>>>>>>> Methods 2) and 4) are same, both making special SMI >>>>>>>> call and Bios handing this request (just 2 is from >>>>>>>> kernel and 4 from userspace) >>>>>>>> >>>>>>>> Method 1) via acpi video driver working, but is not >>>>>>>> perfect. Driver can be used to change brightness (but >>>>>>>> only some levels, probably this depends on acpi/DSDT >>>>>>>> tables), but cannot be used to retrieve current >>>>>>>> brightness (when BIOS/SMI change brightness acpi driver >>>>>>>> report old incorrect value). So I prefer dell-laptop >>>>>>>> driver instead acpi video. >>>>>>>> >>>>>>>> Method 3) working even with 3.17-rc6 kernel but because >>>>>>>> that backlight device exported by i915 is marked as >>>>>>>> raw, desktop programs prefer to use other devices. >>>>>>>> >>>>>>>> Moreover it looks like that methods 1) 2) and 4) just >>>>>>>> forward request to method 3). So in any cased >>>>>>>> brightness is changed by i915 drm driver. >>>>>>>> >>>>>>>> I'm not sure (correct me if I'm wrong!) but I think >>>>>>>> that intel i915 drm driver accept changes (file >>>>>>>> intel_opregion.c) only if acpi function >>>>>>>> acpi_video_verify_backlight_support() returns true. >>>>>>>> >>>>>>>> Function acpi_video_verify_backlight_support() returns >>>>>>>> true iff: function acpi_video_backlight_support() >>>>>>>> returns true AND at least one of these functions >>>>>>>> returns false: acpi_osi_is_win8() >>>>>>>> acpi_video_use_native_backlight() >>>>>>>> backlight_device_registered(BACKLIGHT_RAW) >>>>>>>> >>>>>>>> On my notebook acpi_osi_is_win8() returns true (as is >>>>>>>> win8 compliant), >>>>>>>> backlight_device_registered(BACKLIGHT_RAW) returns true >>>>>>>> as I'm using intel i915 drm driver with raw backlight >>>>>>>> device and acpi_video_use_native_backlight() returns >>>>>>>> true/false depending on >>>>>>>> "video.use_native_backlight" kernel param. Default is >>>>>>>> true. >>>>>>>> >>>>>>>> So if I want to have working acpi video driver with >>>>>>>> display brightness support I need to boot kernel with >>>>>>>> param: "video.use_native_backlight=0". I tested it with >>>>>>>> kernel 3.17-rc6 and this param really enabled display >>>>>>>> brightness support via acpi video driver -- which is >>>>>>>> good. >>>>>>>> >>>>>>>> Driver dell-laptop creating backligh device for >>>>>>>> brightness control only if >>>>>>>> acpi_video_backlight_support() returns false. There is >>>>>>>> complicated condition for it and when kernel is booted >>>>>>>> with "video.use_native_backlight=0" that function >>>>>>>> returns true. >>>>>>>> >>>>>>>> So conclusion is: With current code in kernel 3.17-rc6 >>>>>>>> it is not possible to control brightness of display >>>>>>>> with native driver dell-laptop on Dell Latitude E6440 >>>>>>>> (and probably on others too)!!! >>>>>>>> >>>>>>>> And Because laptop is win8 compliant and you create >>>>>>>> decision to use native driver (instead acpi one) it is >>>>>>>> not possible to control display brightness without >>>>>>>> tweeks in kernel cmdline. >>>>>>>> >>>>>>>> As I wrote I would rather to use native dell-laptop >>>>>>>> driver for controlling brightness, but it is not >>>>>>>> possible. >>>>>>>> >>>>>>>> So how to solve this problem? >>>>>>>> >>>>>>>> Quick solution would be to set use_native_backlight >>>>>>>> false for some Dell laptops which means, that acpi >>>>>>>> video will be used and in this case intel i915 driver >>>>>>>> will *not* drop backlight change request. >>>>>>>> >>>>>>>> Another solution could be to disable check in >>>>>>>> dell_laptop driver and add use_native_backlight=0 to >>>>>>>> hooks. But this create two backlight interfaces (which >>>>>>>> is not good), but only way (for now) how to make >>>>>>>> dell_laptop working again. >>>>>>>> >>>>>>>> Better and maybe only one proper solution would be to >>>>>>>> teach intel drm i915 driver to not drop backlight >>>>>>>> change request for Dell laptops (or all??). (This >>>>>>>> allows to work both acpi video and dell_laptop drivers >>>>>>>> without any change and with *any* value in param >>>>>>>> use_native_backlight). I think that problematic code is >>>>>>>> in function asle_set_backlight() in file >>>>>>>> intel_opregion.c (but I'm not sure). My idea is that >>>>>>>> "drop" event function it is caused by this commit >>>>>>>> 0b9f7d93ca6109048a4eb06332b666b6e29df4fe (but I'm not >>>>>>>> sure). >>>>>>>> >>>>>>>> At least something must be done as I think that I'm not >>>>>>>> only one who has Dell laptop and brightness >>>>>>>> configuration is really important... >>>>>>> >>>>>>> I don't understand your problem, the kernel is selecting >>>>>>> the i915 backlight driver, making that the only one >>>>>>> available to userspace, so the one problem you state >>>>>>> with the i915 driver, that it is "raw" is not an issue, >>>>>>> as userspace will pick it when it is the only one. >>>>>> >>>>>> It is not only one. >>>>> >>>>> Are you sure, if you do not specify any commandline >>>>> parameters, then neither dell-laptop nor acpi-video should >>>>> register a backlight interface. >>>>> >>>>> dell-laptop.c has: >>>>> >>>>> #ifdef CONFIG_ACPI >>>>> >>>>> /* In the event of an ACPI backlight being >>>>> available, >>>>> >>>>> don't * register the platform controller. >>>>> >>>>> */ >>>>> >>>>> if (acpi_video_backlight_support()) >>>>> >>>>> return 0; >>>>> >>>>> #endif >>>>> >>>>> And acpi_video_backlight_support() will (normally) return >>>>> true on acpi-backlight capable systems independent of >>>>> use_native_backlight. >>>>> >>>>> And drivers/acpi/video.c has this: >>>>> /* no warning message if acpi_backlight=vendor or >>>>> a >>>>> >>>>> quirk is used */ if >>>>> (!acpi_video_verify_backlight_support()) >>>>> >>>>> return; >>>>> >>>>> ... >>>>> >>>>> bool acpi_video_verify_backlight_support(void) >>>>> { >>>>> >>>>> if (acpi_osi_is_win8() && >>>>> >>>>> acpi_video_use_native_backlight() && >>>>> backlight_device_registered(BACKLIGHT_RAW)) return false; >>>>> >>>>> return acpi_video_backlight_support(); >>>>> >>>>> } >>>>> >>>>> So unlike the check in dell-laptop this one does depend on >>>>> the use_native_backlight setting. >>>> >>>> It depends (see my previous mail). Here is code: >>>> >>>> static bool acpi_video_use_native_backlight(void) >>>> { >>>> >>>> if (use_native_backlight_param != -1) >>>> >>>> return use_native_backlight_param; >>>> >>>> else >>>> >>>> return use_native_backlight_dmi; >>>> >>>> } >> >> Not sure what you're trying to say here, the default for >> this is 1, so if you don't specify anything, then this: >> >> bool acpi_video_verify_backlight_support(void) >> { >> if (acpi_osi_is_win8() && >> acpi_video_use_native_backlight() && >> backlight_device_registered(BACKLIGHT_RAW)) return false; >> return acpi_video_backlight_support(); >> } >> >> Will return false, and you won't get an acpi_video0 backlight >> interface, only the intel_backlight one, and everything >> should just work (except for the turning off on low >> settings). >> > > When I do not specify param acpi_video_verify_backlight_support() > will return false because acpi_osi_is_win8() returns true. > >> Have you tried not using any kernel commandline options? What >> happens? >> > > Yes, then kernel create two backlight devices: one raw from i915 > module and one normal from dell-laptop module. Erm, no it won't, unless you've other kernel commandline options active as well. dell-laptop contains this: #ifdef CONFIG_ACPI /* In the event of an ACPI backlight being available, don't * register the platform controller. */ if (acpi_video_backlight_support()) return 0; #endif And acpi_video_backlight_support() will still report 1, so dell-laptop will not register a backlight interface unless your meddling with things / config options. > Userspace will > pick dell-laptop for using. And due to commit 0b9f7d93 (which > disabling events when acpi_video_verify_backlight_support returns > false) dell-laptop backlight not working. So controlling > brightness from userspace does not work. Right, so stop doing whatever you are doing which causes dell-laptop to register a backlight interface as by default it will not do that, and your problem is gone. >>>>> I've just checked 3.17 on my E6430 and there this works as >>>>> it should, I only get the intel_backlight in >>>>> /sys/class/backlight >>>>> >>>>>> Also dell-laptop (or acpi video) backlight >>>>>> interface is created (depends on use_native_backlight >>>>>> param). And userspace will pick dell-laptop (or acpi >>>>>> video) to use (which cannot change brightness). >>>>>> >>>>>>> Why would you want to use dell-laptop despite the i915 >>>>>>> driver working fine ? >>>>>> >>>>>> i915 working only if I compile kernel without acpi video >>>>>> dell- laptop support (distributions compile kernel with >>>>>> these drivers) and i915 is not good for usage. First it >>>>>> provides more then thousand brightness levels and lot of >>>>>> (with low numbers) completely turn display off. And if >>>>>> userspace map these thousand levels into 5-10 levels (as >>>>>> nobody want to press brightness key up/down 1000x) two >>>>>> lowest levels cause display off. >>>>> >>>>> More and more laptops will only have working backlight >>>>> control at all when using i915, so userspace will need to >>>>> learn to better deal with backlight controls with these >>>>> ranges. And low pwm levels turning the backlight of is >>>>> normal for raw interfaces, if userspace does not want >>>>> this, then they should not go so low. >>>> >>>> So then kernel should report which low levels turn >>>> backlight off so userspace will know which levels should >>>> avoid. But this is not implemented yet. >>>> >>>>> I suggest that you file a bug against your desktop >>>>> environment that it is not using the backlight controls in >>>>> an optimal manner, from the kernel pov everything is >>>>> working fine. >>>> >>>> Once I will know which levels should not DE use I can >>>> report bug. >>>> >>>>>> With acpi >>>>>> video and dell-laptop driver levels are mapped into small >>>>>> level space in perfect way. So this is reason I want to >>>>>> use dell-laptop for controlling brightness. >>>>> >>>>> If you want to use dell-laptop, specify >>>>> acpi_backlight=vendor on the kernel commandline, that will >>>>> give you dell_laptop + intel_backlight as backlight >>>>> interfaces, and userspace should prefer dell_laptop. >>>> >>>> With acpi_backlight=vendor dell-laptop is not working, see >>>> my previous mail. In this case intel i915 drm driver >>>> ignore bios events for changing brightness. And userspace >>>> prefer to use dell_laptop which do nothing! >>> >>> Ok, that problematic commit is: >>> >>> ACPI / i915: ignore firmware requests for backlight change >>> 0b9f7d93ca6109048a4eb06332b666b6e29df4fe >>> >>> When I reverted it acpi_backlight=vendor started working >>> again (via dell_laptop). Without reverting that commit >>> dell_laptop simply do nothing. >>> >>> Tested and on my laptop Dell Latitude E6440 driver >>> dell_laptop does not work with above commit. >> >> Hmm, interesting, so when dell-laptop registers and makes a >> few calls using the dell-laptop acpi interface, > > No, dell-laptop is *not* acpi driver. See my first mail. It uses > dell dcdbas driver which makes SMI calls for SMBIOS. But it (on > my machine! no idea about other older once) just forward > brightness change to intel driver. And it has useful brightness > levels (no lot of levels which turning display off). > > And making SMI calls can be done also from userspace. There is > tool dellLcdBrightness in libsmbios package which for brightness. > And commit 0b9f7d93ca6109048a4eb06332b666b6e29df4fe broke > functionality of that tool. > >> then you either stop getting key press events through the >> acpi-video-bus, or dell-laptop is just a shim around the i915 >> interface with the firmware calling into itself on these >> models. Given that dell-laptop is ancient, the shim story is >> not that far fetched. >> > > Brightness Fn keys are reported by WMI (dell-wmi driver), so they > working without dell-laptop and acpi video drivers perfectly. > >> Do you still get an on screen display showing the brightness >> when using a kernel without this patch + >> acpi_backlight=vendor ? >> > > Brightness Fn keys are reported to userspace (from WMI input > device) with any combination of video.use_native_backlight and > acpi_backlight kernel params. Ok, so the dell-laptop interface is just an obsolete wrapper around the i915 opregion code, which shows that the right interface to use is the i915 one, which we do if you don't specify any kernel commandline parameters, case closed. Regards, Hans