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Received: from 108-198-5-147.lightspeed.okcbok.sbcglobal.net ([108.198.5.147]:52402 helo=[192.168.0.134]) by vern.gendns.com with esmtpsa (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.92) (envelope-from ) id 1hpxYq-00ACvU-41; Tue, 23 Jul 2019 12:22:44 -0400 Subject: Re: [1/3] RFT: drm/pl111: Support grayscale To: dri-devel@lists.freedesktop.org References: <20190723133755.22677-2-linus.walleij@linaro.org> From: David Lechner Message-ID: <1c988006-af6a-934c-5661-853cd9842c83@lechnology.com> Date: Tue, 23 Jul 2019 11:22:43 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190723133755.22677-2-linus.walleij@linaro.org> Content-Language: en-US X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - vern.gendns.com X-AntiAbuse: Original Domain - lists.infradead.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - lechnology.com X-Get-Message-Sender-Via: vern.gendns.com: authenticated_id: davidmain+lechnology.com/only user confirmed/virtual account not confirmed X-Authenticated-Sender: vern.gendns.com: davidmain@lechnology.com X-Source: X-Source-Args: X-Source-Dir: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190723_092331_674464_EF0E0B31 X-CRM114-Status: GOOD ( 10.90 ) 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: Fabian Vogt , Daniel Tang , Linus Walleij , linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 7/23/19 8:37 AM, Linus Walleij wrote: > Migrating the TI nspire calculators to use the PL111 driver for > framebuffer requires grayscale support for the elder panel > which uses 8bit grayscale only. > > DRM does not support 8bit grayscale framebuffers in memory, > but by defining the bus format to be MEDIA_BUS_FMT_Y8_1X8 we > can get the hardware to turn on a grayscaling feature and > convert the RGB framebuffer to grayscale for us. > What would it take to add proper grayscale framebuffer support to DRM? I've been using the RGB to gray conversion method for a while now with st7586 and it is OK but is creates extra work if you want things to actually look "good" instead of "OK" because you have to add code to userspace programs to craft images in a certain way so that they come out on the other side looking as intended on the actual display. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel