On Sun, 2013-04-07 at 09:56 +0800, Aaron Lu wrote: > Currently we decide if the _BQC is using index by first setting the > level to maximum, and then check if _BQC returned maximum; if not, we > say it is using index. > > This is not true for some buggy systems, where the _BQC method will > always return a constant value(e.g. 0 or 100 for the two broken system) > and thus break the current logic. So this patch tries to enhance the > quirk detect logic for _BQC: we do this by picking a test_level, it can > be the maximum level or the mininum one based on some condition. And we > don't make the assumption that if _BQC returned a value that is not what > we just set, it must be using an index. Instead, we will compare the > value returned from _BQC and if it doesn't match, see if the returned > value is an index. And if still no, clear the capability of _BQC. > > Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=42861 > Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=56011 > Reported-and-tested-by: Artem Savkov <artem.savkov@xxxxxxxxx> > Reported-by: Luis Medinas <lmedinas@xxxxxxxxx> > Reported-by: Cheppes <cheppes@xxxxxxxxxxxxxx> > Signed-off-by: Aaron Lu <aaron.lu@xxxxxxxxx> Acked-by: Zhang Rui <rui.zhang@xxxxxxxxx> thanks, rui > --- > Thanks Cheppes <cheppes@xxxxxxxxxxxxxx> for the suggestion of choosing > different levels to test, and also for the help of in code comment > correction. > > drivers/acpi/video.c | 67 ++++++++++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 57 insertions(+), 10 deletions(-) > > diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c > index 3cdd047..306ea2a 100644 > --- a/drivers/acpi/video.c > +++ b/drivers/acpi/video.c > @@ -632,6 +632,56 @@ acpi_video_cmp_level(const void *a, const void *b) > } > > /* > + * Decides if _BQC/_BCQ for this system is usable > + * > + * We do this by changing the level first and then read out the current > + * brightness level, if the value does not match, find out if it is using > + * index. If not, clear the _BQC/_BCQ capability. > + */ > +static int acpi_video_bqc_quirk(struct acpi_video_device *device, > + int max_level, int current_level) > +{ > + struct acpi_video_device_brightness *br = device->brightness; > + int result; > + unsigned long long level; > + int test_level; > + > + /* don't mess with existing known broken systems */ > + if (bqc_offset_aml_bug_workaround) > + return 0; > + > + /* > + * Some systems always report current brightness level as maximum > + * through _BQC, we need to test another value for them. > + */ > + test_level = current_level == max_level ? br->levels[2] : max_level; > + > + result = acpi_video_device_lcd_set_level(device, test_level); > + if (result) > + return result; > + > + result = acpi_video_device_lcd_get_level_current(device, &level, true); > + if (result) > + return result; > + > + if (level != test_level) { > + /* buggy _BQC found, need to find out if it uses index */ > + if (level < br->count) { > + if (br->flags._BCL_reversed) > + level = br->count - 3 - level; > + if (br->levels[level + 2] == test_level) > + br->flags._BQC_use_index = 1; > + } > + > + if (!br->flags._BQC_use_index) > + device->cap._BQC = device->cap._BCQ = 0; > + } > + > + return 0; > +} > + > + > +/* > * Arg: > * device : video output device (LCD, CRT, ..) > * > @@ -742,18 +792,15 @@ acpi_video_init_brightness(struct acpi_video_device *device) > if (result) > goto out_free_levels; > > - /* > - * Set the level to maximum and check if _BQC uses indexed value > - */ > - result = acpi_video_device_lcd_set_level(device, max_level); > - if (result) > - goto out_free_levels; > - > - result = acpi_video_device_lcd_get_level_current(device, &level, true); > + result = acpi_video_bqc_quirk(device, max_level, level_old); > if (result) > goto out_free_levels; > - > - br->flags._BQC_use_index = (level == max_level ? 0 : 1); > + /* > + * cap._BQC may get cleared due to _BQC is found to be broken > + * in acpi_video_bqc_quirk, so check again here. > + */ > + if (!device->cap._BQC) > + goto set_level; > > if (use_bios_initial_backlight) { > level = acpi_video_bqc_value_to_level(device, level_old); -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
