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[66.90.144.107]) by smtp.gmail.com with ESMTPSA id d20-20020a056871041400b0013c8ae74a14sm6257284oag.42.2022.12.20.10.19.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Dec 2022 10:19:49 -0800 (PST) Received: (nullmailer pid 858419 invoked by uid 1000); Tue, 20 Dec 2022 18:19:48 -0000 Date: Tue, 20 Dec 2022 12:19:48 -0600 From: Rob Herring To: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Cc: devicetree@vger.kernel.org, Fabio Estevam , Daniel Vetter , David Airlie , Sascha Hauer , dri-devel@lists.freedesktop.org, NXP Linux Team , Krzysztof Kozlowski , Philipp Zabel , Shawn Guo , Pengutronix Kernel Team , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v3 0/2] drm/imx/lcdc: Implement DRM driver for imx21 Message-ID: <20221220181948.GA828243-robh@kernel.org> References: <20221216175006.456831-1-u.kleine-koenig@pengutronix.de> <20221216235758.GA88372-robh@kernel.org> <20221217183806.bvo5vypm6axycdte@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20221217183806.bvo5vypm6axycdte@pengutronix.de> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Sat, Dec 17, 2022 at 07:38:06PM +0100, Uwe Kleine-König wrote: > On Fri, Dec 16, 2022 at 05:57:58PM -0600, Rob Herring wrote: > > On Fri, Dec 16, 2022 at 06:50:04PM +0100, Uwe Kleine-König wrote: > > > Hello, > > > > > > Changes since v2: > > > > > > - added allOf as Krzysztof requested > > > - reworked driver based on Philipp's comments > > > (improved error handling, different selects, moved driver to a subdirectory, > > > header sorting, drm_err instead of DRM_ERROR, inlined > > > imx_lcdc_check_mode_change, make use of dev_err_probe()) > > > > > > Krzysztof also pointed out that we're now having two compatibles for a > > > single hardware. Admittedly this is unusual, but this is the chance that > > > the (bad) compatible identifier imx21-fb gets deprecated. The hardware > > > is called LCDC and only the linux (framebuffer) driver is called imxfb. > > > > The problem is you can't have firmware (with the DTB) that supports > > both. Well, you can if you want to have some firmware setting that > > selects which one. Otherwise, it's really an OS problem to decide what > > to use. > > I don't understand what you intend to say here. The same applies if the > compatible is the same for both binding alternatives, isn't it? Only if you have both nodes in the DT and both enabled. But 2 enabled nodes at the same address is also a dtc warning, so I was assuming you didn't do that. > Do you consider a firmware problem better or an OS problem? The OS created the problem, so they get to keep it. But a PC BIOS is full of OS compatibility switches, so... In the end, it's the platforms' decision really. I just want what the implications of having 2 compatibles are to be understood. Rob