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. Maxime
signature.asc
Description: PGP signature
