Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755410Ab3JJMrl (ORCPT ); Thu, 10 Oct 2013 08:47:41 -0400 Received: from hydra.sisk.pl ([212.160.235.94]:50645 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752763Ab3JJMri (ORCPT ); Thu, 10 Oct 2013 08:47:38 -0400 From: "Rafael J. Wysocki" To: Aaron Lu Cc: linux-acpi@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Daniel Vetter , Matthew Garrett , Seth Forshee , Lee Chun-Yi , Richard Purdie , Igor Gnatenko , Yves-Alexis Perez , Felipe Contreras , Jani Nikula , Ben Jencks , Steven Newbury , James Hogan , Kamal Mostafa , Joerg Platte , Kalle Valo , Martin Steigerwald , =?ISO-8859-1?Q?J=F6rg?= Otte , Mike Galbraith , platform-driver-x86@vger.kernel.org, Mika Westerberg , Henrique de Moraes Holschuh Subject: Re: [PATCH v4 3/4] ACPI / video: Do not register backlight if win8 and native interface exists Date: Thu, 10 Oct 2013 14:59:02 +0200 Message-ID: <2800253.nfx2dehBQN@vostro.rjw.lan> User-Agent: KMail/4.10.5 (Linux/3.11.0+; KDE/4.10.5; x86_64; ; ) In-Reply-To: <5255FCBF.6090708@intel.com> References: <1381214401-24672-1-git-send-email-aaron.lu@intel.com> <9897358.0Z0t2PgJOe@vostro.rjw.lan> <5255FCBF.6090708@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6474 Lines: 151 On Thursday, October 10, 2013 09:02:55 AM Aaron Lu wrote: > On 10/10/2013 08:29 AM, Rafael J. Wysocki wrote: > > On Tuesday, October 08, 2013 02:40:00 PM Aaron Lu wrote: > >> According to 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 [8] 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". > >> > >> So for Win8 systems, if there is native backlight control interface > >> registered by GPU driver, ACPI video will not register its own. For > >> users who prefer to keep ACPI video's backlight interface, the existing > >> kernel cmdline option acpi_backlight=video can be used. > >> > >> Signed-off-by: Aaron Lu > >> Tested-by: Igor Gnatenko > >> Tested-by: Yves-Alexis Perez > >> Tested-by: Mika Westerberg > >> --- > >> drivers/acpi/internal.h | 5 ++--- > >> drivers/acpi/video.c | 10 +++++----- > >> drivers/acpi/video_detect.c | 14 ++++++++++++-- > >> 3 files changed, 19 insertions(+), 10 deletions(-) > >> > >> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h > >> index 20f4233..453ae8d 100644 > >> --- a/drivers/acpi/internal.h > >> +++ b/drivers/acpi/internal.h > >> @@ -169,9 +169,8 @@ int acpi_create_platform_device(struct acpi_device *adev, > >> Video > >> -------------------------------------------------------------------------- */ > >> #if defined(CONFIG_ACPI_VIDEO) || defined(CONFIG_ACPI_VIDEO_MODULE) > >> -bool acpi_video_backlight_quirks(void); > >> -#else > >> -static inline bool acpi_video_backlight_quirks(void) { return false; } > >> +bool acpi_osi_is_win8(void); > >> +bool acpi_video_verify_backlight_support(void); > >> #endif > >> > >> #endif /* _ACPI_INTERNAL_H_ */ > >> diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c > >> index 3bd1eaa..343db59 100644 > >> --- a/drivers/acpi/video.c > >> +++ b/drivers/acpi/video.c > >> @@ -1256,8 +1256,8 @@ acpi_video_switch_brightness(struct acpi_video_device *device, int event) > >> unsigned long long level_current, level_next; > >> int result = -EINVAL; > >> > >> - /* no warning message if acpi_backlight=vendor is used */ > >> - if (!acpi_video_backlight_support()) > >> + /* no warning message if acpi_backlight=vendor or a quirk is used */ > >> + if (!acpi_video_verify_backlight_support()) > >> return 0; > >> > >> if (!device->brightness) > >> @@ -1386,13 +1386,13 @@ acpi_video_bus_get_devices(struct acpi_video_bus *video, > >> static int acpi_video_bus_start_devices(struct acpi_video_bus *video) > >> { > >> return acpi_video_bus_DOS(video, 0, > >> - acpi_video_backlight_quirks() ? 1 : 0); > >> + acpi_osi_is_win8() ? 1 : 0); > >> } > >> > >> static int acpi_video_bus_stop_devices(struct acpi_video_bus *video) > >> { > >> return acpi_video_bus_DOS(video, 0, > >> - acpi_video_backlight_quirks() ? 0 : 1); > >> + acpi_osi_is_win8() ? 0 : 1); > >> } > >> > >> static void acpi_video_bus_notify(struct acpi_device *device, u32 event) > >> @@ -1558,7 +1558,7 @@ acpi_video_bus_match(acpi_handle handle, u32 level, void *context, > >> > >> static void acpi_video_dev_register_backlight(struct acpi_video_device *device) > >> { > >> - if (acpi_video_backlight_support()) { > >> + if (acpi_video_verify_backlight_support()) { > >> struct backlight_properties props; > >> struct pci_dev *pdev; > >> acpi_handle acpi_parent; > >> diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c > >> index 940edbf..23d7d26 100644 > >> --- a/drivers/acpi/video_detect.c > >> +++ b/drivers/acpi/video_detect.c > >> @@ -37,6 +37,7 @@ > >> #include > >> #include > >> #include > >> +#include > >> > >> #include "internal.h" > >> > >> @@ -233,11 +234,11 @@ static void acpi_video_caps_check(void) > >> acpi_video_get_capabilities(NULL); > >> } > >> > >> -bool acpi_video_backlight_quirks(void) > >> +bool acpi_osi_is_win8(void) > >> { > >> return acpi_gbl_osi_data >= ACPI_OSI_WIN_8; > >> } > >> -EXPORT_SYMBOL(acpi_video_backlight_quirks); > >> +EXPORT_SYMBOL(acpi_osi_is_win8); > >> > >> /* Promote the vendor interface instead of the generic video module. > >> * This function allow DMI blacklists to be implemented by externals > >> @@ -283,6 +284,15 @@ int acpi_video_backlight_support(void) > >> } > >> EXPORT_SYMBOL(acpi_video_backlight_support); > >> > >> +bool acpi_video_verify_backlight_support(void) > >> +{ > >> + if (!(acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO) && > >> + acpi_osi_is_win8() && backlight_device_registered(BACKLIGHT_RAW)) > >> + return false; > > > > If I'm not mistaken, this will introduce a regression for the people who have > > problems with the native i915 backlight on Win8-compatible systems. I'd prefer > > to avoid that at this point. > > > > OK, I see. > > Then I'm afraid a new kernel command line option is needed, something > like video.use_native_backlight and set it to false by default, then > for people who need to avoid the ACPI video backlight interface, they > can add video.use_native_backlight=true to kernel cmdline. > > One thing I need to mention is, with the new cmdline option, users will > need to manually add a kernel cmdline option to make backlight work on > their systems, while they can already make backlight work by modifying > xorg.conf to specify using intel_backlight interface, so it doesn't seem > this patchset will be very useful then... Except if we add a (black)list of systems where that option will be 'true' by default instead of the _OSI blacklist we have today. Also we can switch the default during development cycles to get an idea about how many systems are affected and maybe we can find a way to fix them, in which case we can simply drop the option. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/