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a=rsa-sha256; c=relaxed/relaxed; d=ew.tq-group.com; s=dkim; t=1741167334; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Jyc0o/VMOXI30xo+J36YcCxvEuBKWlv1PliS5DKyB2A=; b=rN9bkF/64KDDTPYAyySZk0Mm0QNhup6z5oj0FdVBAJZjJE3bsTsZc4IrHgusmWoLXEdRfI 3moeKx8BUzdxufYlLxK9uTJJSD/f9UHhUodtpxkAiiS7fVcDdR8uVIXxMP4nsm7g+/F6iG tzLt7nOzX/+NGGSUBHDVSeIEdT8qNofcL/iM+VJL58YtoyYKDQo53dXBR1O/aQ6cUwWXRB mxzHyJ3JzEcS1mHeZDs5kHKI529jrZoYjponLS7KZRBlJr55rx2GM+q8uGrt61SVqmRcyk E+2Ppd1dlHzFasqxvSSGWtwtXEzDSVxlS8pRk6nQeDzSFOz5UQRx2lMwF3mmkg== From: Alexander Stein To: Liu Ying , dri-devel@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, andrzej.hajda@intel.com, neil.armstrong@linaro.org, rfoss@kernel.org, Laurent.pinchart@ideasonboard.com, jonas@kwiboo.se, jernej.skrabec@gmail.com, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch, Rob Herring Subject: Re: [PATCH 3/5] dt-bindings: display: simple-bridge: Document DPI color encoder Date: Wed, 05 Mar 2025 10:35:26 +0100 Message-ID: <1891036.atdPhlSkOF@steina-w> Organization: TQ-Systems GmbH In-Reply-To: <20250304152320.GA2630063-robh@kernel.org> References: <20250304101530.969920-1-victor.liu@nxp.com> <20250304101530.969920-4-victor.liu@nxp.com> <20250304152320.GA2630063-robh@kernel.org> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1" X-Last-TLS-Session-Version: TLSv1.3 Hi, Am Dienstag, 4. M=E4rz 2025, 16:23:20 CET schrieb Rob Herring: > On Tue, Mar 04, 2025 at 06:15:28PM +0800, Liu Ying wrote: > > A DPI color encoder, as a simple display bridge, converts input DPI col= or > > coding to output DPI color coding, like Adafruit Kippah DPI hat[1] which > > converts input 18-bit pixel data to 24-bit pixel data(with 2 low padding > > bits in every color component though). Document the DPI color encoder. >=20 > Why do we need a node for this? Isn't this just wired how it is wired=20 > and there's nothing for s/w to see or do? I suppose if you are trying to= =20 > resolve the mode with 24-bit on one end and 18-bit on the other end, you= =20 > need to allow that and not require an exact match. You still might need=20 > to figure out which pins the 18-bit data comes out on, but you have that= =20 > problem with an 18-bit panel too. IOW, how is this any different if you=20 > have an 18-bit panel versus 24-bit panel? Especially panel-simple.c has a fixed configuration for each display, such = as: > .bus_format =3D MEDIA_BUS_FMT_RGB666_1X18 How would you allow or even know it should be addressed as MEDIA_BUS_FMT_RGB888_1X24 instead? I see different ways: 1. Create a new display setting/compatible 2. Add an overwrite property to the displays 3. Use a (transparent) bridge (this series) Number 1 is IMHO out of question. I personally don't like number 2 as this feels like adding quirks to displays, which they don't have. Number 3 actually describe the hardware connection. The only impact for software is to know which bus format it should use. Best regards Alexander =2D-=20 TQ-Systems GmbH | M=FChlstra=DFe 2, Gut Delling | 82229 Seefeld, Germany Amtsgericht M=FCnchen, HRB 105018 Gesch=E4ftsf=FChrer: Detlef Schneider, R=FCdiger Stahl, Stefan Schneider http://www.tq-group.com/