* Question about ACPI Video
@ 2010-01-25 9:45 luke lin
2010-01-26 0:58 ` Zhang Rui
0 siblings, 1 reply; 5+ messages in thread
From: luke lin @ 2010-01-25 9:45 UTC (permalink / raw)
To: linux-acpi; +Cc: Luke lin
Hi all,
I read the drivers/acpi/video.c:
895 result = acpi_video_device_lcd_set_level(device, max_level);
896 if (result)
897 goto out_free_levels;
898
899 result = acpi_video_device_lcd_get_level_current(device, &level);
900 if (result)
901 goto out_free_levels;
902
903 br->flags._BQC_use_index = (level == max_level ? 0 : 1);
904
905 if (!br->flags._BQC_use_index) {
912 for (i = 2; i < br->count; i++)
913 if (level_old == br->levels[i])
914 level = level_old;
915 goto set_level;
916 }
why after level == max_level, it will still need set_level again?
is this a bug, or it is necessary.
thx
luke
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Question about ACPI Video
2010-01-25 9:45 Question about ACPI Video luke lin
@ 2010-01-26 0:58 ` Zhang Rui
2010-01-26 3:24 ` Len Brown
2010-01-27 18:02 ` Edward Shao
0 siblings, 2 replies; 5+ messages in thread
From: Zhang Rui @ 2010-01-26 0:58 UTC (permalink / raw)
To: luke lin; +Cc: linux-acpi, Luke lin
On Mon, 2010-01-25 at 17:45 +0800, luke lin wrote:
> Hi all,
>
> I read the drivers/acpi/video.c:
>
> 895 result = acpi_video_device_lcd_set_level(device, max_level);
> 896 if (result)
> 897 goto out_free_levels;
> 898
> 899 result = acpi_video_device_lcd_get_level_current(device, &level);
> 900 if (result)
> 901 goto out_free_levels;
> 902
> 903 br->flags._BQC_use_index = (level == max_level ? 0 : 1);
> 904
> 905 if (!br->flags._BQC_use_index) {
> 912 for (i = 2; i < br->count; i++)
> 913 if (level_old == br->levels[i])
> 914 level = level_old;
> 915 goto set_level;
> 916 }
> why after level == max_level, it will still need set_level again?
> is this a bug, or it is necessary.
>
Because setting the backlight to max_level is just to check if _BQC uses
indexed value. We need to set the backlight back after this is done.
thanks,
rui
> thx
> luke
> --
> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Question about ACPI Video
2010-01-26 0:58 ` Zhang Rui
@ 2010-01-26 3:24 ` Len Brown
2010-01-27 18:02 ` Edward Shao
1 sibling, 0 replies; 5+ messages in thread
From: Len Brown @ 2010-01-26 3:24 UTC (permalink / raw)
To: Zhang Rui; +Cc: luke lin, linux-acpi, Luke lin
> > why after level == max_level, it will still need set_level again?
> > is this a bug, or it is necessary.
> >
> Because setting the backlight to max_level is just to check if _BQC uses
> indexed value. We need to set the backlight back after this is done.
perhaps a good place for a comment?
thanks,
Len Brown, Intel Open Source Technology Center
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Question about ACPI Video
2010-01-26 0:58 ` Zhang Rui
2010-01-26 3:24 ` Len Brown
@ 2010-01-27 18:02 ` Edward Shao
2010-01-28 7:04 ` Zhang Rui
1 sibling, 1 reply; 5+ messages in thread
From: Edward Shao @ 2010-01-27 18:02 UTC (permalink / raw)
To: Zhang Rui; +Cc: linux-acpi, Luke lin
On Tue, Jan 26, 2010 at 8:58 AM, Zhang Rui <rui.zhang@intel.com> wrote:
> On Mon, 2010-01-25 at 17:45 +0800, luke lin wrote:
>> Hi all,
>>
>> I read the drivers/acpi/video.c:
>>
>> 895 result = acpi_video_device_lcd_set_level(device, max_level);
>> 896 if (result)
>> 897 goto out_free_levels;
>> 898
>> 899 result = acpi_video_device_lcd_get_level_current(device, &level);
>> 900 if (result)
>> 901 goto out_free_levels;
>> 902
>> 903 br->flags._BQC_use_index = (level == max_level ? 0 : 1);
>> 904
>> 905 if (!br->flags._BQC_use_index) {
>> 912 for (i = 2; i < br->count; i++)
>> 913 if (level_old == br->levels[i])
>> 914 level = level_old;
>> 915 goto set_level;
>> 916 }
>> why after level == max_level, it will still need set_level again?
>> is this a bug, or it is necessary.
>>
> Because setting the backlight to max_level is just to check if _BQC uses
> indexed value. We need to set the backlight back after this is done.
>
> thanks,
> rui
Hi~
I'm wondering why check (level == max_level) can make sure if _BQC
uses indexed value?
Is it possible that both level and max_level is indexed value?
Thank you very much.
--
Best Regards,
Edward
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Question about ACPI Video
2010-01-27 18:02 ` Edward Shao
@ 2010-01-28 7:04 ` Zhang Rui
0 siblings, 0 replies; 5+ messages in thread
From: Zhang Rui @ 2010-01-28 7:04 UTC (permalink / raw)
To: Edward Shao; +Cc: linux-acpi, Luke lin
On Thu, 2010-01-28 at 02:02 +0800, Edward Shao wrote:
> On Tue, Jan 26, 2010 at 8:58 AM, Zhang Rui <rui.zhang@intel.com> wrote:
> > On Mon, 2010-01-25 at 17:45 +0800, luke lin wrote:
> >> Hi all,
> >>
> >> I read the drivers/acpi/video.c:
> >>
> >> 895 result = acpi_video_device_lcd_set_level(device, max_level);
> >> 896 if (result)
> >> 897 goto out_free_levels;
> >> 898
> >> 899 result = acpi_video_device_lcd_get_level_current(device, &level);
> >> 900 if (result)
> >> 901 goto out_free_levels;
> >> 902
> >> 903 br->flags._BQC_use_index = (level == max_level ? 0 : 1);
> >> 904
> >> 905 if (!br->flags._BQC_use_index) {
> >> 912 for (i = 2; i < br->count; i++)
> >> 913 if (level_old == br->levels[i])
> >> 914 level = level_old;
> >> 915 goto set_level;
> >> 916 }
> >> why after level == max_level, it will still need set_level again?
> >> is this a bug, or it is necessary.
> >>
> > Because setting the backlight to max_level is just to check if _BQC uses
> > indexed value. We need to set the backlight back after this is done.
> >
> > thanks,
> > rui
>
> Hi~
>
> I'm wondering why check (level == max_level) can make sure if _BQC
> uses indexed value?
> Is it possible that both level and max_level is indexed value?
>
If both _BQC and _BCL uses indexed value, then we don't need to treat
them as indexed value. :p
for example,
_BCL returns {0, 1, 2, 3, 4, 5, ... }, the index of level n is n.
If _BQC uses indexed value, it should returns n for level n.
so this equals a BIOS that both _BCL and _BQC use percentage values.
thanks,
rui
> Thank you very much.
>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2010-01-28 7:06 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2010-01-25 9:45 Question about ACPI Video luke lin
2010-01-26 0:58 ` Zhang Rui
2010-01-26 3:24 ` Len Brown
2010-01-27 18:02 ` Edward Shao
2010-01-28 7:04 ` Zhang Rui
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