Hi Maxime, Thank you for the patch.
On Thu, May 20, 2021 at 04:24:35PM +0200, Maxime Ripard wrote: > New KMS properties come with a bunch of requirements to avoid each > driver from running their own, inconsistent, set of properties, > eventually leading to issues like property conflicts, inconsistencies > between drivers and semantics, etc. > > Let's document what we expect. > > Cc: Alexandre Belloni <alexandre.bell...@bootlin.com> > Cc: Alexandre Torgue <alexandre.tor...@foss.st.com> > Cc: Alex Deucher <alexander.deuc...@amd.com> > Cc: Alison Wang <alison.w...@nxp.com> > Cc: Alyssa Rosenzweig <alyssa.rosenzw...@collabora.com> > Cc: Andrew Jeffery <and...@aj.id.au> > Cc: Andrzej Hajda <a.ha...@samsung.com> > Cc: Anitha Chrisanthus <anitha.chrisant...@intel.com> > Cc: Benjamin Gaignard <benjamin.gaign...@linaro.org> > Cc: Ben Skeggs <bske...@redhat.com> > Cc: Boris Brezillon <bbrezil...@kernel.org> > Cc: Brian Starkey <brian.star...@arm.com> > Cc: Chen Feng <puck.c...@hisilicon.com> > Cc: Chen-Yu Tsai <w...@csie.org> > Cc: Christian Gmeiner <christian.gmei...@gmail.com> > Cc: "Christian König" <christian.koe...@amd.com> > Cc: Chun-Kuang Hu <chunkuang...@kernel.org> > Cc: Edmund Dea <edmund.j....@intel.com> > Cc: Eric Anholt <e...@anholt.net> > Cc: Fabio Estevam <feste...@gmail.com> > Cc: Gerd Hoffmann <kra...@redhat.com> > Cc: Haneen Mohammed <hamohammed...@gmail.com> > Cc: Hans de Goede <hdego...@redhat.com> > Cc: "Heiko Stübner" <he...@sntech.de> > Cc: Huang Rui <ray.hu...@amd.com> > Cc: Hyun Kwon <hyun.k...@xilinx.com> > Cc: Inki Dae <inki....@samsung.com> > Cc: Jani Nikula <jani.nik...@linux.intel.com> > Cc: Jernej Skrabec <jernej.skra...@siol.net> > Cc: Jerome Brunet <jbru...@baylibre.com> > Cc: Joel Stanley <j...@jms.id.au> > Cc: John Stultz <john.stu...@linaro.org> > Cc: Jonas Karlman <jo...@kwiboo.se> > Cc: Jonathan Hunter <jonath...@nvidia.com> > Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com> > Cc: Joonyoung Shim <jy0922.s...@samsung.com> > Cc: Jyri Sarha <jyri.sa...@iki.fi> > Cc: Kevin Hilman <khil...@baylibre.com> > Cc: Kieran Bingham <kieran.bingham+rene...@ideasonboard.com> > Cc: Krzysztof Kozlowski <krzysztof.kozlow...@canonical.com> > Cc: Kyungmin Park <kyungmin.p...@samsung.com> > Cc: Laurent Pinchart <laurent.pinch...@ideasonboard.com> > Cc: Linus Walleij <linus.wall...@linaro.org> > Cc: Liviu Dudau <liviu.du...@arm.com> > Cc: Lucas Stach <l.st...@pengutronix.de> > Cc: Ludovic Desroches <ludovic.desroc...@microchip.com> > Cc: Marek Vasut <ma...@denx.de> > Cc: Martin Blumenstingl <martin.blumensti...@googlemail.com> > Cc: Matthias Brugger <matthias....@gmail.com> > Cc: Maxime Coquelin <mcoquelin.st...@gmail.com> > Cc: Maxime Ripard <mrip...@kernel.org> > Cc: Melissa Wen <melissa....@gmail.com> > Cc: Neil Armstrong <narmstr...@baylibre.com> > Cc: Nicolas Ferre <nicolas.fe...@microchip.com> > Cc: "Noralf Trønnes" <nor...@tronnes.org> > Cc: NXP Linux Team <linux-...@nxp.com> > Cc: Oleksandr Andrushchenko <oleksandr_andrushche...@epam.com> > Cc: Patrik Jakobsson <patrik.r.jakobs...@gmail.com> > Cc: Paul Cercueil <p...@crapouillou.net> > Cc: Pengutronix Kernel Team <ker...@pengutronix.de> > Cc: Philippe Cornu <philippe.co...@foss.st.com> > Cc: Philipp Zabel <p.za...@pengutronix.de> > Cc: Qiang Yu <yuq...@gmail.com> > Cc: Rob Clark <robdcl...@gmail.com> > Cc: Robert Foss <robert.f...@linaro.org> > Cc: Rob Herring <r...@kernel.org> > Cc: Rodrigo Siqueira <rodrigosiqueiram...@gmail.com> > Cc: Rodrigo Vivi <rodrigo.v...@intel.com> > Cc: Roland Scheidegger <srol...@vmware.com> > Cc: Russell King <li...@armlinux.org.uk> > Cc: Sam Ravnborg <s...@ravnborg.org> > Cc: Sandy Huang <h...@rock-chips.com> > Cc: Sascha Hauer <s.ha...@pengutronix.de> > Cc: Sean Paul <s...@poorly.run> > Cc: Seung-Woo Kim <sw0312....@samsung.com> > Cc: Shawn Guo <shawn...@kernel.org> > Cc: Stefan Agner <ste...@agner.ch> > Cc: Steven Price <steven.pr...@arm.com> > Cc: Sumit Semwal <sumit.sem...@linaro.org> > Cc: Thierry Reding <thierry.red...@gmail.com> > Cc: Tian Tao <tiant...@hisilicon.com> > Cc: Tomeu Vizoso <tomeu.viz...@collabora.com> > Cc: Tomi Valkeinen <to...@kernel.org> > Cc: VMware Graphics <linux-graphics-maintai...@vmware.com> > Cc: Xinliang Liu <xinliang....@linaro.org> > Cc: Xinwei Kong <kong.kongxin...@hisilicon.com> > Cc: Yannick Fertre <yannick.fer...@foss.st.com> > Cc: Zack Rusin <za...@vmware.com> > Reviewed-by: Daniel Vetter <daniel.vet...@ffwll.ch> > Signed-off-by: Maxime Ripard <max...@cerno.tech> > > --- > > Changes from v2: > - Typos and wording reported by Daniel and Alex > --- > Documentation/gpu/drm-kms.rst | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst > index 87e5023e3f55..c28b464dd397 100644 > --- a/Documentation/gpu/drm-kms.rst > +++ b/Documentation/gpu/drm-kms.rst > @@ -463,6 +463,25 @@ KMS Properties > This section of the documentation is primarily aimed at user-space > developers. > For the driver APIs, see the other sections. > > +Requirements > +------------ > + > +KMS drivers might need to add extra properties to support new features. > +Each new property introduced in a driver need to meet a few s/need/needs/ > +requirements, in addition to the one mentioned above.: s/above./above/ > + > +- It must be standardized, with some documentation to describe how the > + property can be used. > + > +- It must provide a generic helper in the core code to register that > + property on the object it attaches to. > + > +- Its content must be decoded by the core and provided in the object's > + associated state structure. That includes anything drivers might want to > + precompute, like :c:type:`struct drm_clip_rect <drm_clip_rect>` for planes. Does this effectively mean that we completely forbid driver-specific properties ? While I agree that we should strive for standardization, there are two issues that worry me. The first one is simple, we may need to control features that would be very device-specific, and standardizing properties doesn't seem to make much sense in that case. The second issue relates to properties that could be applicable to multiple devices, but for which we have a single driver. Designing a standard with a single data point usually leads to a bad design. I'm not sure how to handle this correctly though, as we certainly don't want this to be taken as an excuse to create driver-specific properties when generic properties would make sense. > +- An IGT test must be submitted where reasonable. > + > Property Types and Blob Property Support > ---------------------------------------- > -- Regards, Laurent Pinchart
