Hi, On Wed, Jul 08, 2026 at 01:11:49PM +0300, Cristian Ciocaltea wrote: > On 7/7/26 7:10 PM, Maxime Ripard wrote: > > On Fri, Jul 03, 2026 at 10:31:55PM +0300, Cristian Ciocaltea wrote: > >> Hi Dmitry, > >> > >> Thanks for your quick review! > >> > >> On 7/3/26 5:05 PM, Dmitry Baryshkov wrote: > >>> On Thu, Jul 02, 2026 at 05:46:15PM +0300, Cristian Ciocaltea wrote: > >>>> In preparation for adding HDMI 2.x source capabilities, introduce struct > >>>> drm_connector_hdmi_caps and a new drmm_connector_hdmi_init_with_caps() > >>>> helper. > >>>> > >>>> The existing drmm_connector_hdmi_init() helper currently takes > >>>> individual capability arguments such as supported_formats and max_bpc. > >>>> Adding more HDMI-specific arguments to that function would not scale > >>>> well, so move those values into a dedicated capabilities structure and > >>>> implement the existing helper as a wrapper around the new caps-based > >>>> interface. > >>> > >>> I think, it was an intention of Maxime: make sure that every driver is > >>> forced to provide some values here. With the struct-based init it is > >>> easy to overlook or to ommit a value. > >> > >> Agreed that the struct-based init loses the compile-time guarantee that > >> every > >> argument is explicitly provided - that's a real downside. > >> > >> I'd argue it's recoverable, though: the init helper validates the mandatory > >> fields, so a driver that omits a required value gets rejected at init time > >> rather than silently misconfigured. The "you must provide sane values" > >> property > >> is expected to be preserved, just enforced at runtime instead of by the > >> compiler. > > > > Yeah, I don't think we can win with C here. Rust might, but we're > > probably a long way from that. > > > >> The main motivation for the struct is scalability/maintainability as we > >> add HDMI > >> 2.x capabilities: new fields go into the struct rather than growing the > >> helper's > >> argument list, so existing callers don't need churny signature updates on > >> every > >> extension. > >> > >> FWIW, in the previous revision we discussed addressing the concern with a > >> callback instead. Sadly, I had to discard that approach, as it proved not > >> flexible enough, e.g. drm_bridge_connector_init() computes caps > >> dynamically, and > >> would have required either stateful callbacks, or storing > >> redundant/temporary > >> cap data in driver-private structures just to satisfy the callback. > > > > I just realized something reviewing your patch: we don't necessarily > > need an extra argument or a callback, we can just put these fields into > > drm_hdmi_connector_funcs directly, and then validate them in init. > > If I understand correctly, we should drop the drm_connector_hdmi_caps struct > introduced by this patch and move all its fields into > drm_hdmi_connector_funcs. > > In that case, how should we proceed with drmm_connector_hdmi_init()? I see the > following options: > > 1. Continue with drmm_connector_hdmi_init_with_caps() after removing the caps > parameter, and then drop drmm_connector_hdmi_init() after the migration.
If we're going that road, we can also move the format, bpc and vendor and product there for example. > 2. Keep the existing (unaltered) drmm_connector_hdmi_init(), which would be > slightly inconsistent: supported_formats and max_bpc would still be passed > as arguments, while the rest would go through drm_hdmi_connector_funcs. I'm not sure why we would want to do that? > 3. A variation of option 1: additionally rename > drmm_connector_hdmi_init_with_caps() to drmm_connector_hdmi_init() after > the > migration. It should be renamed indeed. Maxime
signature.asc
Description: PGP signature
