* [PATCH 6/7] ACPI video: introduce module parameter video.use_bios_initial_backlight
@ 2010-12-06 7:04 Zhang Rui
2010-12-06 16:03 ` Randy Dunlap
2010-12-14 5:10 ` Len Brown
0 siblings, 2 replies; 4+ messages in thread
From: Zhang Rui @ 2010-12-06 7:04 UTC (permalink / raw)
To: Brown, Len; +Cc: linux-acpi@vger.kernel.org, Matthew Garrett, Zhang, Rui
Introduce module parameter video.use_bios_initial_backlight.
Some BIOSes claim they use the minimum backlight at boot,
and this may bring dimming screen after boot.
https://bugzilla.kernel.org/show_bug.cgi?id=21212
use video.use_bios_initl_backlight=0 to use
the maximum backlight level after boot.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
---
drivers/acpi/video.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
Index: linux-2.6/drivers/acpi/video.c
===================================================================
--- linux-2.6.orig/drivers/acpi/video.c
+++ linux-2.6/drivers/acpi/video.c
@@ -80,6 +80,13 @@ module_param(brightness_switch_enabled,
static int allow_duplicates;
module_param(allow_duplicates, bool, 0644);
+/*
+ * Some BIOSes claim they use minimum backlight at boot,
+ * and this may bring dimming screen after boot
+ */
+static int use_bios_initial_backlight = 1;
+module_param(use_bios_initial_backlight, bool, 0644);
+
static int register_count = 0;
static int acpi_video_bus_add(struct acpi_device *device);
static int acpi_video_bus_remove(struct acpi_device *device, int type);
@@ -705,9 +712,11 @@ acpi_video_init_brightness(struct acpi_v
* when invoked for the first time, i.e. level_old is invalid.
* set the backlight to max_level in this case
*/
- for (i = 2; i < br->count; i++)
- if (level_old == br->levels[i])
- level = level_old;
+ if (use_bios_initial_backlight) {
+ for (i = 2; i < br->count; i++)
+ if (level_old == br->levels[i])
+ level = level_old;
+ }
goto set_level;
}
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 6/7] ACPI video: introduce module parameter video.use_bios_initial_backlight
2010-12-06 7:04 [PATCH 6/7] ACPI video: introduce module parameter video.use_bios_initial_backlight Zhang Rui
@ 2010-12-06 16:03 ` Randy Dunlap
2010-12-14 5:10 ` Len Brown
1 sibling, 0 replies; 4+ messages in thread
From: Randy Dunlap @ 2010-12-06 16:03 UTC (permalink / raw)
To: Zhang Rui; +Cc: Brown, Len, linux-acpi@vger.kernel.org, Matthew Garrett
On Mon, 06 Dec 2010 15:04:27 +0800 Zhang Rui wrote:
>
> Introduce module parameter video.use_bios_initial_backlight.
>
> Some BIOSes claim they use the minimum backlight at boot,
> and this may bring dimming screen after boot.
> https://bugzilla.kernel.org/show_bug.cgi?id=21212
>
> use video.use_bios_initl_backlight=0 to use
> the maximum backlight level after boot.
Hi,
Where is this documented?
> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> ---
> drivers/acpi/video.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> Index: linux-2.6/drivers/acpi/video.c
> ===================================================================
> --- linux-2.6.orig/drivers/acpi/video.c
> +++ linux-2.6/drivers/acpi/video.c
> @@ -80,6 +80,13 @@ module_param(brightness_switch_enabled,
> static int allow_duplicates;
> module_param(allow_duplicates, bool, 0644);
>
> +/*
> + * Some BIOSes claim they use minimum backlight at boot,
> + * and this may bring dimming screen after boot
> + */
> +static int use_bios_initial_backlight = 1;
> +module_param(use_bios_initial_backlight, bool, 0644);
> +
> static int register_count = 0;
> static int acpi_video_bus_add(struct acpi_device *device);
> static int acpi_video_bus_remove(struct acpi_device *device, int type);
> @@ -705,9 +712,11 @@ acpi_video_init_brightness(struct acpi_v
> * when invoked for the first time, i.e. level_old is invalid.
> * set the backlight to max_level in this case
> */
> - for (i = 2; i < br->count; i++)
> - if (level_old == br->levels[i])
> - level = level_old;
> + if (use_bios_initial_backlight) {
> + for (i = 2; i < br->count; i++)
> + if (level_old == br->levels[i])
> + level = level_old;
> + }
> goto set_level;
> }
>
>
>
> --
---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 6/7] ACPI video: introduce module parameter video.use_bios_initial_backlight
2010-12-06 7:04 [PATCH 6/7] ACPI video: introduce module parameter video.use_bios_initial_backlight Zhang Rui
2010-12-06 16:03 ` Randy Dunlap
@ 2010-12-14 5:10 ` Len Brown
2010-12-14 5:21 ` Zhang Rui
1 sibling, 1 reply; 4+ messages in thread
From: Len Brown @ 2010-12-14 5:10 UTC (permalink / raw)
To: Zhang Rui; +Cc: linux-acpi@vger.kernel.org, Matthew Garrett
On Mon, 6 Dec 2010, Zhang Rui wrote:
>
> Introduce module parameter video.use_bios_initial_backlight.
there must be a more concise way to say that...
> Some BIOSes claim they use the minimum backlight at boot,
> and this may bring dimming screen after boot.
> https://bugzilla.kernel.org/show_bug.cgi?id=21212
>
> use video.use_bios_initl_backlight=0 to use
> the maximum backlight level after boot.
this looks like a BIOS workaround.
should there be a way to invoke this workaround automatically?
thanks,
-Len
>
> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> ---
> drivers/acpi/video.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> Index: linux-2.6/drivers/acpi/video.c
> ===================================================================
> --- linux-2.6.orig/drivers/acpi/video.c
> +++ linux-2.6/drivers/acpi/video.c
> @@ -80,6 +80,13 @@ module_param(brightness_switch_enabled,
> static int allow_duplicates;
> module_param(allow_duplicates, bool, 0644);
>
> +/*
> + * Some BIOSes claim they use minimum backlight at boot,
> + * and this may bring dimming screen after boot
> + */
> +static int use_bios_initial_backlight = 1;
> +module_param(use_bios_initial_backlight, bool, 0644);
> +
> static int register_count = 0;
> static int acpi_video_bus_add(struct acpi_device *device);
> static int acpi_video_bus_remove(struct acpi_device *device, int type);
> @@ -705,9 +712,11 @@ acpi_video_init_brightness(struct acpi_v
> * when invoked for the first time, i.e. level_old is invalid.
> * set the backlight to max_level in this case
> */
> - for (i = 2; i < br->count; i++)
> - if (level_old == br->levels[i])
> - level = level_old;
> + if (use_bios_initial_backlight) {
> + for (i = 2; i < br->count; i++)
> + if (level_old == br->levels[i])
> + level = level_old;
> + }
> goto set_level;
> }
>
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 6/7] ACPI video: introduce module parameter video.use_bios_initial_backlight
2010-12-14 5:10 ` Len Brown
@ 2010-12-14 5:21 ` Zhang Rui
0 siblings, 0 replies; 4+ messages in thread
From: Zhang Rui @ 2010-12-14 5:21 UTC (permalink / raw)
To: Len Brown; +Cc: linux-acpi@vger.kernel.org, Matthew Garrett
On Tue, 2010-12-14 at 13:10 +0800, Len Brown wrote:
> On Mon, 6 Dec 2010, Zhang Rui wrote:
>
> >
> > Introduce module parameter video.use_bios_initial_backlight.
>
> there must be a more concise way to say that...
>
> > Some BIOSes claim they use the minimum backlight at boot,
> > and this may bring dimming screen after boot.
> > https://bugzilla.kernel.org/show_bug.cgi?id=21212
> >
> > use video.use_bios_initl_backlight=0 to use
> > the maximum backlight level after boot.
>
> this looks like a BIOS workaround.
yes.
> should there be a way to invoke this workaround automatically?
>
no.
because it's hard for software to detect if the screen is dark.
maybe we need another dmi list for this issue.
thanks,
rui
> thanks,
> -Len
>
> >
> > Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> > ---
> > drivers/acpi/video.c | 15 ++++++++++++---
> > 1 file changed, 12 insertions(+), 3 deletions(-)
> >
> > Index: linux-2.6/drivers/acpi/video.c
> > ===================================================================
> > --- linux-2.6.orig/drivers/acpi/video.c
> > +++ linux-2.6/drivers/acpi/video.c
> > @@ -80,6 +80,13 @@ module_param(brightness_switch_enabled,
> > static int allow_duplicates;
> > module_param(allow_duplicates, bool, 0644);
> >
> > +/*
> > + * Some BIOSes claim they use minimum backlight at boot,
> > + * and this may bring dimming screen after boot
> > + */
> > +static int use_bios_initial_backlight = 1;
> > +module_param(use_bios_initial_backlight, bool, 0644);
> > +
> > static int register_count = 0;
> > static int acpi_video_bus_add(struct acpi_device *device);
> > static int acpi_video_bus_remove(struct acpi_device *device, int type);
> > @@ -705,9 +712,11 @@ acpi_video_init_brightness(struct acpi_v
> > * when invoked for the first time, i.e. level_old is invalid.
> > * set the backlight to max_level in this case
> > */
> > - for (i = 2; i < br->count; i++)
> > - if (level_old == br->levels[i])
> > - level = level_old;
> > + if (use_bios_initial_backlight) {
> > + for (i = 2; i < br->count; i++)
> > + if (level_old == br->levels[i])
> > + level = level_old;
> > + }
> > goto set_level;
> > }
> >
> >
> >
^ permalink raw reply [flat|nested] 4+ messages in thread
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Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2010-12-06 7:04 [PATCH 6/7] ACPI video: introduce module parameter video.use_bios_initial_backlight Zhang Rui
2010-12-06 16:03 ` Randy Dunlap
2010-12-14 5:10 ` Len Brown
2010-12-14 5:21 ` Zhang Rui
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