On 4/27/21 6:00 AM, Daniel Vetter wrote: > On Tue, Apr 27, 2021 at 10:40:24AM +0300, Pekka Paalanen wrote: >> On Mon, 26 Apr 2021 14:30:53 -0300 >> Leandro Ribeiro <leandro.ribeiro@xxxxxxxxxxxxx> wrote: >> >>> On 4/26/21 7:58 AM, Simon Ser wrote: >>>> On Monday, April 26th, 2021 at 9:36 AM, Pekka Paalanen <ppaalanen@xxxxxxxxx> wrote: >>>> >>>>>>> This should probably explain what the bits in the mask correspond to. >>>>>>> As in, which CRTC does bit 0 refer to, and so on. >>>>>> >>>>>> What about: >>>>>> >>>>>> "possible_crtcs: Bitmask of CRTC's compatible with the plane. CRTC's are >>>>>> created and they receive an index, which corresponds to their position >>>>>> in the bitmask. CRTC with index 0 will be in bit 0, and so on." >>>>> >>>>> This would still need to explain where can I find this index. >>>> >>> >>> What do you mean? >>> >>>> This closed merge request had some docs about possible CRTCs: >>>> >>>> https://gitlab.freedesktop.org/mesa/drm/-/merge_requests/102 >>>> >>> I'm afraid I don't know exactly what you expect to be documented here >>> that is still missing. Could you please elaborate? >>> >>> Thanks a lot! >> >> The documentation you add is talking about "CRTC index". What defines a >> CRTC object's index? How do I determine what index a CRTC object has? >> >> The answer is, AFAIK, that the index is never stored explicitly >> anywhere. You have to get the DRM resources structure, which has an >> array for CRTC IDs. The index is the index to that array, IIRC. So if >> one does not already know this, it is going to be really hard to figure >> out what the "index" is. It might even be confused with the object ID, >> which it is not but the ID might by complete accident be less than 32 >> so it would look ok at first glance. >> >> If the index is already explained somewhere else, a reference to that >> documentation would be enough. > > I think if we do this we should have a DOC: section in the drm_mode.h uapi > header which explains how the index is computed, and then we reference > that everywhere. Because otherwise there's going to be a _lot_ of > duplication of this all over. Kernel-internally we solve this by just > referencing drm_foo_index() family of functions, but for the uapi there's > really nothing, so needs text. > > -Daniel > Ok, I've sent a v3 with a small section to document how to get the index of a CRTC object from userspace perspective. But I could only find two comments that would benefit from it (at least in "Userland interfaces" page). Thanks! _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
