We can still map 1000 entries back to 256, it will just mean some of them won't result in any brightness change. If that's not acceptable, I guess a dynamic 1:1 mapping is sufficient. Jesse On Tue, 18 Nov 2014 23:18:35 +0000 "Eoff, Ullysses A" <ullysses.a.eoff@xxxxxxxxx> wrote: > Thanks Jesse for the ack. > > Unfortunately I just learned from Stéphane that there > are certain devices which only support 256 levels, so this > patch would do us no good at solving the real issue for > such devices. > > Why can't we just use a dynamic 1:1 mapping as was > suggested before? I would vote for that instead. > > ---- > U. Artie > > > -----Original Message----- > > From: Jesse Barnes [mailto:jbarnes@xxxxxxxxxxxxxxxx] > > Sent: Tuesday, November 18, 2014 9:23 AM > > To: Eoff, Ullysses A > > Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Jani Nikula > > Subject: Re: [PATCH] drm/i915: expose a fixed brightness range to userspace > > > > On Tue, 11 Nov 2014 12:30:38 -0800 > > "U. Artie Eoff" <ullysses.a.eoff@xxxxxxxxx> wrote: > > > > > A userspace brightness range that is larger than the hardware > > > brightness range does not have a 1:1 mapping and can result > > > in brightness != actual_brightness for some values. > > > > > > Expose a fixed brightness range of [0..1000] to userspace so > > > that all values can map 1:1 into the hardware brightness > > > range. This would assume that the hardware range is always > > > greater than 1000, otherwise we're right back to the original > > > issue. > > > > > > This patch is based on Jani Nikula's proposed change in the > > > referenced ML thread, except use the range [0..1000] instead; > > > which was recommended by Jesse Barnes for smoother backlight > > > transitions. > > > > > > Reference: http://lists.freedesktop.org/archives/intel-gfx/2014-November/055221.html > > > Signed-off-by: U. Artie Eoff <ullysses.a.eoff@xxxxxxxxx> > > > --- > > > drivers/gpu/drm/i915/intel_panel.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c > > > index 4d63839..f74f5f2 100644 > > > --- a/drivers/gpu/drm/i915/intel_panel.c > > > +++ b/drivers/gpu/drm/i915/intel_panel.c > > > @@ -1057,7 +1057,7 @@ static int intel_backlight_device_register(struct intel_connector *connector) > > > * Note: Everything should work even if the backlight device max > > > * presented to the userspace is arbitrarily chosen. > > > */ > > > - props.max_brightness = panel->backlight.max; > > > + props.max_brightness = 1000; > > > props.brightness = scale_hw_to_user(connector, > > > panel->backlight.level, > > > props.max_brightness); > > > > Yeah looks ok to me. I guess Jani has to ack it too. > > > > Reviewed-by: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx> > > > > -- > > Jesse Barnes, Intel Open Source Technology Center > -- Jesse Barnes, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
