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[80.7.220.175]) by smtp.gmail.com with ESMTPSA id s2sm7540795wmh.9.2020.10.28.07.56.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Oct 2020 07:56:19 -0700 (PDT) Date: Wed, 28 Oct 2020 14:56:17 +0000 From: Daniel Thompson To: Alexandru Stan Cc: Heiko Stuebner , Rob Herring , Andy Gross , Bjorn Andersson , Thierry Reding , Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= , Lee Jones , Jingoo Han , Bartlomiej Zolnierkiewicz , Douglas Anderson , Matthias Kaehlcke , Enric Balletbo i Serra , devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 2/3] arm64: dts: qcom: trogdor: Add brightness-levels Message-ID: <20201028145617.ermdpqomthxxj7qe@holly.lan> References: <20201022050445.930403-1-amstan@chromium.org> <20201021220404.v3.2.Ie4d84af5a85e8dcb8f575845518fa39f324a827d@changeid> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201021220404.v3.2.Ie4d84af5a85e8dcb8f575845518fa39f324a827d@changeid> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 21, 2020 at 10:04:44PM -0700, Alexandru Stan wrote: > We want userspace to represent the human perceived brightness. > Since the led drivers and the leds themselves don't have a > linear response to the value we give them in terms of perceived > brightness, we'll bake the curve into the dts. > > The panel also doesn't have a good response under 5%, so we'll avoid > sending it anything lower than that. > > Note: Ideally this patch should be coupled with the driver change from > "backlight: pwm_bl: Fix interpolation", but it can work without it, > without looking too ugly. > > Signed-off-by: Alexandru Stan Acked-by: Daniel Thompson > --- > > 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>; > + > pwms = <&cros_ec_pwm 1>; > enable-gpios = <&tlmm 12 GPIO_ACTIVE_HIGH>; > power-supply = <&ppvar_sys>; > -- > 2.28.0