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 <[email protected]> > Cc: Alexandre Torgue <[email protected]> > Cc: Alex Deucher <[email protected]> > Cc: Alison Wang <[email protected]> > Cc: Alyssa Rosenzweig <[email protected]> > Cc: Andrew Jeffery <[email protected]> > Cc: Andrzej Hajda <[email protected]> > Cc: Anitha Chrisanthus <[email protected]> > Cc: Benjamin Gaignard <[email protected]> > Cc: Ben Skeggs <[email protected]> > Cc: Boris Brezillon <[email protected]> > Cc: Brian Starkey <[email protected]> > Cc: Chen Feng <[email protected]> > Cc: Chen-Yu Tsai <[email protected]> > Cc: Christian Gmeiner <[email protected]> > Cc: "Christian König" <[email protected]> > Cc: Chun-Kuang Hu <[email protected]> > Cc: Edmund Dea <[email protected]> > Cc: Eric Anholt <[email protected]> > Cc: Fabio Estevam <[email protected]> > Cc: Gerd Hoffmann <[email protected]> > Cc: Haneen Mohammed <[email protected]> > Cc: Hans de Goede <[email protected]> > Cc: "Heiko Stübner" <[email protected]> > Cc: Huang Rui <[email protected]> > Cc: Hyun Kwon <[email protected]> > Cc: Inki Dae <[email protected]> > Cc: Jani Nikula <[email protected]> > Cc: Jernej Skrabec <[email protected]> > Cc: Jerome Brunet <[email protected]> > Cc: Joel Stanley <[email protected]> > Cc: John Stultz <[email protected]> > Cc: Jonas Karlman <[email protected]> > Cc: Jonathan Hunter <[email protected]> > Cc: Joonas Lahtinen <[email protected]> > Cc: Joonyoung Shim <[email protected]> > Cc: Jyri Sarha <[email protected]> > Cc: Kevin Hilman <[email protected]> > Cc: Kieran Bingham <[email protected]> > Cc: Krzysztof Kozlowski <[email protected]> > Cc: Kyungmin Park <[email protected]> > Cc: Laurent Pinchart <[email protected]> > Cc: Linus Walleij <[email protected]> > Cc: Liviu Dudau <[email protected]> > Cc: Lucas Stach <[email protected]> > Cc: Ludovic Desroches <[email protected]> > Cc: Marek Vasut <[email protected]> > Cc: Martin Blumenstingl <[email protected]> > Cc: Matthias Brugger <[email protected]> > Cc: Maxime Coquelin <[email protected]> > Cc: Maxime Ripard <[email protected]> > Cc: Melissa Wen <[email protected]> > Cc: Neil Armstrong <[email protected]> > Cc: Nicolas Ferre <[email protected]> > Cc: "Noralf Trønnes" <[email protected]> > Cc: NXP Linux Team <[email protected]> > Cc: Oleksandr Andrushchenko <[email protected]> > Cc: Patrik Jakobsson <[email protected]> > Cc: Paul Cercueil <[email protected]> > Cc: Pengutronix Kernel Team <[email protected]> > Cc: Philippe Cornu <[email protected]> > Cc: Philipp Zabel <[email protected]> > Cc: Qiang Yu <[email protected]> > Cc: Rob Clark <[email protected]> > Cc: Robert Foss <[email protected]> > Cc: Rob Herring <[email protected]> > Cc: Rodrigo Siqueira <[email protected]> > Cc: Rodrigo Vivi <[email protected]> > Cc: Roland Scheidegger <[email protected]> > Cc: Russell King <[email protected]> > Cc: Sam Ravnborg <[email protected]> > Cc: Sandy Huang <[email protected]> > Cc: Sascha Hauer <[email protected]> > Cc: Sean Paul <[email protected]> > Cc: Seung-Woo Kim <[email protected]> > Cc: Shawn Guo <[email protected]> > Cc: Stefan Agner <[email protected]> > Cc: Steven Price <[email protected]> > Cc: Sumit Semwal <[email protected]> > Cc: Thierry Reding <[email protected]> > Cc: Tian Tao <[email protected]> > Cc: Tomeu Vizoso <[email protected]> > Cc: Tomi Valkeinen <[email protected]> > Cc: VMware Graphics <[email protected]> > Cc: Xinliang Liu <[email protected]> > Cc: Xinwei Kong <[email protected]> > Cc: Yannick Fertre <[email protected]> > Cc: Zack Rusin <[email protected]> > Reviewed-by: Daniel Vetter <[email protected]> > Signed-off-by: Maxime Ripard <[email protected]> > > --- > > 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
