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[73.63.253.164]) by smtp.gmail.com with ESMTPSA id o8sm1207075pjf.37.2020.07.20.21.27.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Jul 2020 21:27:06 -0700 (PDT) From: Alexandru Stan To: Thierry Reding , =?utf-8?q?Uwe_Kleine-K=C3=B6n?= =?utf-8?q?ig?= , Lee Jones , Daniel Thompson , Jingoo Han , Bartlomiej Zolnierkiewicz , Heiko Stuebner , Rob Herring Subject: [PATCH 0/3] PWM backlight interpolation adjustments Date: Mon, 20 Jul 2020 21:25:19 -0700 Message-Id: <20200721042522.2403410-1-amstan@chromium.org> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200721_002711_682213_41D7FA22 X-CRM114-Status: GOOD ( 11.73 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:541 listed in] [list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.0 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devicetree@vger.kernel.org, linux-fbdev@vger.kernel.org, Alexandru Stan , linux-pwm@vger.kernel.org, Douglas Anderson , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org, Matthias Kaehlcke , Enric Balletbo i Serra , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org I was trying to adjust the brightness for a new chromebook: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2291209 Like a lot of panels, the low end needs to be cropped, and now that we have the interpolation stuff I wanted to make use of it and bake in even the curve. I found the behavior a little unintuitive and non-linear. See patch 1 for a suggested fix for this. Unfortunatelly a few veyron dts files were relying on this (perhaps weird) behavior. Those devices also want a minimum brightness. The issue is that they also want the 0% point for turning off the display. https://github.com/torvalds/linux/commit/6233269bce47bd450196a671ab28eb1ec5eb88d9#diff-e401ae20091bbfb311a062c464f4f47fL23 So the idea here is to change those dts files to only say <3 255> (patch 3), and add in a virtual 0% point at the bottom of the scale (patch 2). We have to do this conditionally because it seems some devices like to have the scale inverted: % git grep "brightness-levels\s*=\s*<\s*[1-9]"|cat arch/arm/boot/dts/tegra124-apalis-eval.dts: brightness-levels = <255 231 223 207 191 159 127 0>; Alexandru Stan (3): backlight: pwm_bl: Fix interpolation backlight: pwm_bl: Artificially add 0% during interpolation ARM: dts: rockchip: Remove 0 point in backlight arch/arm/boot/dts/rk3288-veyron-jaq.dts | 2 +- arch/arm/boot/dts/rk3288-veyron-minnie.dts | 2 +- arch/arm/boot/dts/rk3288-veyron-tiger.dts | 2 +- drivers/video/backlight/pwm_bl.c | 78 +++++++++++----------- 4 files changed, 42 insertions(+), 42 deletions(-)