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[2003:e4:1f4b:7100:f22f:74ff:fe1f:3a53]) by smtp.gmail.com with ESMTPSA id mj6-20020a170906af8600b00988781076e2sm9224352ejb.78.2023.07.17.06.25.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Jul 2023 06:25:09 -0700 (PDT) Date: Mon, 17 Jul 2023 15:25:07 +0200 From: Thierry Reding To: Dmitry Osipenko Cc: Svyatoslav Ryhel , David Heidelberg , Raffaele Tranquillini , Ion Agorria , Maxim Schwalm , Pedro =?utf-8?Q?=C3=82ngelo?= , Matt Merhar , Zack Pearsall , linux-tegra@vger.kernel.org Subject: Re: LVDS panel compatible strings Message-ID: References: <78ba744f-d7f6-2388-0330-1a5105c9dca5@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="X7db3DuSi1x05WRv" Content-Disposition: inline In-Reply-To: <78ba744f-d7f6-2388-0330-1a5105c9dca5@gmail.com> User-Agent: Mutt/2.2.10 (2023-03-25) Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org --X7db3DuSi1x05WRv Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jul 17, 2023 at 11:50:03AM +0300, Dmitry Osipenko wrote: > 17.07.2023 10:16, Thierry Reding =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > > For cases where the timings are the only things that differ, the DT > > bindings allow overriding the timings specifically. So you might get > > away with using one of the existing panels if it is close enough and > > patch up the timings in DT. >=20 > If panel-simple supported timings override from DT, then panel-lvds > indeed could be removed. But panel-simple doesn't support it: >=20 > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?= id=3Da21f18a993c56566db94ba836684bc32c070a82c I clearly didn't look at that patch closely enough. panel-simple has supported override modes since: commit b8a2948fa2b3a5a6da67fd57aa01c7318d795125 Author: Sean Paul Date: Thu Jul 11 13:34:53 2019 -0700 drm/panel: simple: Add ability to override typical timing =20 This patch adds the ability to override the typical display timing for a given panel. This is useful for devices which have timing constraints that do not apply across the entire display driver (eg: to avoid crosstalk between panel and digitizer on certain laptops). The rules are as follows: =20 - panel must not specify fixed mode (since the override mode will either be the same as the fixed mode, or we'll be unable to check the bounds of the overried) - panel must specify at least one display_timing range which will be used to ensure the override mode fits within its bounds =20 Changes in v2: - Parse the full display-timings node (using the native-mode) (Rob) Changes in v3: - No longer parse display-timings subnode, use panel-timing (Rob) Changes in v4: - Don't add mode from timing if override was specified (Thierry) - Add warning if timing and fixed mode was specified (Thierry) - Don't add fixed mode if timing was specified (Thierry) - Refactor/rename a bit to avoid extra indentation from "if" tests - i should be unsigned (Thierry) - Add annoying WARN_ONs for some cases (Thierry) - Simplify 'No display_timing found' handling (Thierry) - Rename to panel_simple_parse_override_mode() (Thierry) Changes in v5: - Added Heiko's Tested-by Changes in v6: - Rebased to drm-misc next - Added tags =20 Cc: Doug Anderson Cc: Eric Anholt Cc: Heiko Stuebner Cc: Jeffy Chen Cc: Rob Herring Cc: St=C3=A9phane Marchesin Cc: Thierry Reding Cc: devicetree@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: Sean Paul Tested-by: Enric Balletbo i Serra Signed-off-by: Douglas Anderson Tested-by: Heiko Stuebner Reviewed-by: Boris Brezillon Acked-by: Thierry Reding Signed-off-by: Sam Ravnborg Link: https://patchwork.freedesktop.org/patch/msgid/20190711203455.1256= 67-2-dianders@chromium.org Looking at the error message cited in the linked commit, the problem is that the Chunghwa panel has a fixed mode listed in the driver. However I don't see a reason why we can't get rid of that. The only place where I can find the compatible string for that used is for the Nexus 7, so we should be able to replace the fixed mode with the timings for that panel and remove the fixed mode. The initial Chunghwa panel driver support doesn't seem to have been based on the Nexus 7, so I suppose if we make the above change we could technically be breaking some setup out there, but since we have no way of knowing which device this was on, or if anybody still has access, the best we can do is hope that nothing breaks and fix things up if somebody complains. Thierry --X7db3DuSi1x05WRv Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAmS1QTAACgkQ3SOs138+ s6HkgxAAgWtTOcf+zRMFN2Ink1aBdURgA97iK8LMR7oxLbHh4kz+pI6QkzE/TxNu 2kq44Xqcdl9iqHFspUcNVjGVyv18ywqTRt/KoE8QeRefAlqFv7hq6wzehwroat7X os8yZy77ikfu0GFin/yQ9fRj5glTx90wOj39nZ40l8Az3se1KVuIdOycaaWcl22k 6dPUvMmFNOHbwyBTexX/qpAOJxl0QAqwmhk32KGzQ2QJbXVP0FlUedU+CkWXNWFJ QS/L1fbgdi405Ha8nnu7JlYNSSbPRf4MIPgduRutma5aVTeFKGUef5WFmPrldc5k LdETB/sWnLrCfe0pyvHtLtTvXXfZW62ezBZ6mnFNBgVcV+Ctpd59SjTziwGX0fco XqkvU3nAEIhlbv6fg4VrQL8j9OkEjPHnfqa8L1egrs5B8UVhnSY5yB/3b04Q9PsL +mqjfjxusk0uDXYe6WG850YW4jl+++28DCR/Y+eKxq7ekP54xS7eDMA3xc1hYpJf 2ecEBHrWeCyvr6uNIuP4k2Efwuaklw5Bx3GTKyPS5NzfcgKyVTMeZgRjBXga8SnX qyoClUfFJAsORpxfOAcaAmtpaQHC9dC8VeXFciQpKRJgoBlTCFiOPDuU2GwHyWR4 IdsDyu0mGX/Gz8g2N9SYWaCdFBTSvHIOvopT4lhIqpFTZo1taP0= =ENI6 -----END PGP SIGNATURE----- --X7db3DuSi1x05WRv--