Re: [PATCH v2 3/3] arm64: dts: qcom: trogdor: Add brightness-levels

From: Daniel Thompson <daniel.thompson@linaro.org>
To: Doug Anderson <dianders@chromium.org>
Cc: "Alexandru Stan" <amstan@chromium.org>,
	"Thierry Reding" <thierry.reding@gmail.com>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Lee Jones" <lee.jones@linaro.org>,
	"Jingoo Han" <jingoohan1@gmail.com>,
	"Bartlomiej Zolnierkiewicz" <b.zolnierkie@samsung.com>,
	"Heiko Stuebner" <heiko@sntech.de>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Andy Gross" <agross@kernel.org>,
	"Bjorn Andersson" <bjorn.andersson@linaro.org>,
	"Enric Balletbo i Serra" <enric.balletbo@collabora.com>,
	"Matthias Kaehlcke" <mka@chromium.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree@vger.kernel.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 3/3] arm64: dts: qcom: trogdor: Add brightness-levels
Date: Wed, 14 Oct 2020 12:33:13 +0100	[thread overview]
Message-ID: <20201014113313.y5uzugw5lpcbo46p@holly.lan> (raw)
In-Reply-To: <CAD=FV=W4fv_AdS7G2FFe2Kan3YYJ4D0MVJD90aJMrgCja5N4vg@mail.gmail.com>

On Tue, Oct 13, 2020 at 09:28:38AM -0700, Doug Anderson wrote:
> Hi,
> 
> On Tue, Oct 13, 2020 at 1:01 AM Alexandru Stan <amstan@chromium.org> wrote:
> >
> > Now that we have better interpolation for the backlight
> > ("backlight: pwm_bl: Fix interpolation"), we can now add the curve to
> > the trogdor boards, being careful to crop the low end.
> 
> Just to make it clear, the patch this depends on hasn't landed yet.
> Presumably it will land in the v5.10 timeframe?  That means that
> without extra coordination this patch can target v5.11.

You're talking about patch 1 from this set? Despite the title I view
the patch as changing policy (albeit one that does also fix some annoying
quantization errors at the same time) so it's not necessarily a
candidate for merging outside the merge window (I've not checked with
Lee but I think it likely the shutter is already down for features).

Moreover I'm not clear why there a dependency here that would stop the
changes landing in different trees.

Daniel.

> > Signed-off-by: Alexandru Stan <amstan@chromium.org>
> > ---
> >
> >  arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> > index bf875589d364..ccdabc6c4994 100644
> > --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> > +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> > @@ -179,6 +179,15 @@ pp3300_fp_tp: pp3300-fp-tp-regulator {
> >         backlight: backlight {
> >                 compatible = "pwm-backlight";
> >
> > +               /* The panels don't seem to like anything below ~ 5% */
> > +               brightness-levels = <
> > +                       196 256 324 400 484 576 676 784 900 1024 1156 1296
> > +                       1444 1600 1764 1936 2116 2304 2500 2704 2916 3136
> > +                       3364 3600 3844 4096
> > +               >;
> > +               num-interpolated-steps = <64>;
> > +               default-brightness-level = <951>;
> 
> I haven't done lots of digging here, but this matches what Alexandru
> and Matthias agreed upon for the downstream tree and seems sane.
> Thus:
> 
> Reviewed-by: Douglas Anderson <dianders@chromium.org>