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bh=QFgcSxDwjQGmQohC290QGXRTuVmXVyuOEalaNkjC4ws=; b=ffvFEagvHMxcxYiWtdroyPQNdvLv1ifz3VFkmfX4Ma1/lCwCnkcQ1z5TloYCThJtsNEbVR Tl/HXf05ZSSsQobwVSpvnrzOwTaoF2ngm/scJqKUw4cv0uYRkdxjpM1gD8kqvNzOsB7587 mJ0C7A89FtwW3hcIYb3WEx0KSbOMoDe2FjigWHBimIoYM7Y08gzh8unAKgbBlc/8Y2Ts11 Apq5W3jhmeRmm2svhWKmIIw4sHHpyUfjA7BCBRKtOdMPEnAR6VoYOa4zbh4TFL1Dd15DKi 1nAQwvVkD6UErGkIJJIuJwWxon9Z21z/34FWPZaLONeELfD6Cis5CRYWNdejRw== Date: Tue, 2 Dec 2025 13:56:05 +0100 From: Kory Maincent To: Tomi Valkeinen Cc: Krzysztof Kozlowski , Markus Schneider-Pargmann , Luca Ceresoli , Louis Chauvet , Thomas Petazzoni , Miguel Gazquez , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, Jyri Sarha , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Russell King , Bartosz Golaszewski , Tony Lindgren , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec Subject: Re: [PATCH 05/21] ARM: dts: omap: Bind panel to panel-dpi instead of ti,tilcdc,panel driver Message-ID: <20251202135605.053ada96@kmaincent-XPS-13-7390> In-Reply-To: <1d9a9269-bfda-4d43-938b-2df6b82b9369@ideasonboard.com> References: <20251126-feature_tilcdc-v1-0-49b9ef2e3aa0@bootlin.com> <20251126-feature_tilcdc-v1-5-49b9ef2e3aa0@bootlin.com> <96b1b7bf-ddbe-4213-a201-dc89cf2998dd@ideasonboard.com> <3bc5bf92-05c3-4841-ab28-9bab2bb31cd5@kernel.org> <20251202104244.59a9e83d@kmaincent-XPS-13-7390> <20251202114416.09624a4b@kmaincent-XPS-13-7390> <94e254fa-289d-41ed-909f-1742cfbb2690@kernel.org> <20251202121856.0da62885@kmaincent-XPS-13-7390> <1d9a9269-bfda-4d43-938b-2df6b82b9369@ideasonboard.com> Organization: bootlin X-Mailer: Claws Mail 4.2.0 (GTK 3.24.41; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Last-TLS-Session-Version: TLSv1.3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251202_045621_382419_A09C6DC8 X-CRM114-Status: GOOD ( 35.47 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 2 Dec 2025 13:51:59 +0200 Tomi Valkeinen wrote: > Hi Kory, >=20 > On 02/12/2025 13:18, Kory Maincent wrote: > > On Tue, 2 Dec 2025 11:47:40 +0100 > > Krzysztof Kozlowski wrote: > I will not NAK, removing bindings and breaking users is under some > conditions acceptable. You just need to come with the reasons and impact. >=20 > Reason "is ugly" is usually not good enough. Especially if things were > working. Thanks for you reply. > >> > >> DTS cannot go to drm, which means you either need to separate the chan= ge > >> and make entire work bisectable and backwards compatible for some time > >> OR at least document clearly the impact as we always ask. =20 > >=20 > > The thing is, if I split it, it has to be in 3. One for the of DRM bus = flags > > support, a second for the the devicetree and binding change and a third= for > > the whole tilcdc and tda998x cleaning stuff. I think I will go for one > > series, with better documentation. > >=20 > > Now, what is your point of view on my question. Will you nak any binding > > removal even if the binding is ugly and legacy and imply maintaining an > > non-standard tilcdc panel driver? I know it breaks DTB compatibility but > > there is several argument to not keep it. See patch 6. =20 > The binding being ugly and having to maintain non-standard tilcdc panel > driver may be nice things for us, the users don't care. The users care > if their board no longer works. Yes I understand but then I have another question. At what cost should we continue to support legacy binding? Just figured out this case already happened, ti,tilcdc,slave binding was removed from the tilcdc driver: 739acd85ffdb7 ("drm/tilcdc: Remove obsolete "ti,tilcdc,slave" dts binding support") Even if there is still one mainline device tree that uses it: am335x-base0033.dts. :/ > And how does this sync with u-boot? It also has code for at least for a > few of these boards. U-boot has indeed a driver for the ti,tilcdc,panel binding. Changing this devicetree would beak display for these board in U-boot as it currently does not support the "panel-dpi" binding. > Are there even users for these boards? If not, maybe they can be just > removed? I'm personally not familiar with these boards, so I have no > idea of their age or distribution. These boards are quite old (>10 years) but I don't know if they are still u= sed by people. After a quick look they seem not available on the market. > One trick that can be done is to modify the loaded DTB at boot time, > detecting the old format, converting it to the new one, so that when the > drivers are probed they only see the new DTB. Yes, indeed that could do the trick. The things is, I don't have one of theses board to test it. I will try to look for an other way to test it. Regards, --=20 K=C3=B6ry Maincent, Bootlin Embedded Linux and kernel engineering https://bootlin.com