On Fri, Aug 26, 2011 at 01:31:38PM +0200, David Herrmann wrote:
> On Fri, Aug 26, 2011 at 11:58 AM, Jason Stubbs <jasonbstubbs@xxxxxxxxx> wrote:
> > From: Jason Stubbs <jasonbstubbs@xxxxxxxxx>
> >
> > On some Samsung laptops the brightness regulation works slightly different.
> > All SABI commands except for set_brightness work as expected. The behaviour
> > of set_brightness is as follows:
> >
> > - Setting a new brightness will only step one level toward the new brightness
> > level. For example, setting a level of 5 when the current level is 2 will
> > result in a brightness level of 3.
> > - A spurious KEY_BRIGHTNESS_UP or KEY_BRIGHTNESS_DOWN event is also generated
> > along with the change in brightness.
> > - Neither of the above two issues occur when changing from/to brightness
> > level 0.
> >
> > This patch adds detection and a non-intrusive workaround for the above issues.
> >
> > Signed-off-by: Jason Stubbs <jasonbstubbs@xxxxxxxxx>
> >
> > ---
> >
> > diff --git a/drivers/platform/x86/samsung-laptop.c b/drivers/platform/x86/samsung-laptop.c
> > index ee68c1c..b193bf0 100644
> > --- a/drivers/platform/x86/samsung-laptop.c
> > +++ b/drivers/platform/x86/samsung-laptop.c
> > @@ -226,6 +226,7 @@ static struct backlight_device *backlight_device;
> > static struct mutex sabi_mutex;
> > static struct platform_device *sdev;
> > static struct rfkill *rfk;
> > +static bool has_stepping_quirk;
> >
> > static int force;
> > module_param(force, bool, 0);
> > @@ -382,6 +383,17 @@ static void set_brightness(u8 user_brightness)
> > {
> > u8 user_level = user_brightness + sabi_config->min_brightness;
> >
> > + if (has_stepping_quirk && user_level != 0) {
> > + /*
> > + * short circuit if the specified level is what's already set
> > + * to prevent the screen from flickering needlessly
> > + */
> > + if (user_brightness == read_brightness())
> > + return;
> > +
> > + sabi_set_command(sabi_config->commands.set_brightness, 0);
> > + }
> > +
> > sabi_set_command(sabi_config->commands.set_brightness, user_level);
> > }
> >
> > @@ -390,6 +402,34 @@ static int get_brightness(struct backlight_device *bd)
> > return (int)read_brightness();
> > }
> >
> > +static void check_for_stepping_quirk(void)
> > +{
> > + u8 initial_level = read_brightness();
> > + u8 check_level;
> > +
> > + /*
> > + * Some laptops exhibit the strange behaviour of stepping toward
> > + * (rather than setting) the brightness except when changing to/from
> > + * brightness level 0. This behaviour is checked for here and worked
> > + * around in set_brightness.
> > + */
> > +
> > + if (initial_level <= 2)
> > + check_level = initial_level + 2;
> > + else
> > + check_level = initial_level - 2;
> > +
> > + has_stepping_quirk = false;
> > + set_brightness(check_level);
> > +
> > + if (read_brightness() != check_level) {
> > + has_stepping_quirk = true;
> > + pr_info("enabled workaround for brightness stepping quirk\n");
> > + }
> > +
> > + set_brightness(initial_level);
> > +}
> > +
> > static int update_status(struct backlight_device *bd)
> > {
> > set_brightness(bd->props.brightness);
> > @@ -796,6 +836,9 @@ static int __init samsung_init(void)
> > }
> > }
> >
> > + /* Check for stepping quirk */
> > + check_for_stepping_quirk();
> > +
> > /* knock up a platform device to hang stuff off of */
> > sdev = platform_device_register_simple("samsung", -1, NULL, 0);
> > if (IS_ERR(sdev))
> >
> >
>
> Thank you, Jason.
> Tested-by: David Herrmann <dh.herrmann@xxxxxxxxxxxxxx>
>
> And Greg, could you actually "git add" the new samsung patches in your
> repository? You added them to "series" but didn't submit the actual
> patch files. That would be great.
Now done, sorry about that.
greg k-h
--
To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
