Thanks Thierry and Daniel for concluding this discussion, while I was on vacation. Here are the next steps, which I am planning to go for (Please correct me if my understanding is not right) - Shashank to review first of the SCDC patch, and give comments or R-B. - Shashank to work on Thierry's review comments on HF-VSDB parsing patch (including creation of a sub-class nested drm_hdmi_info within drm_display_info) and publish V2 - Thierry/Daniel to review V2 and give comments or R-B Regards Shashank -----Original Message----- From: Daniel Vetter [mailto:daniel.vetter@xxxxxxxx] On Behalf Of Daniel Vetter Sent: Tuesday, December 6, 2016 1:49 PM To: Thierry Reding <thierry.reding@xxxxxxxxx> Cc: Daniel Vetter <daniel@xxxxxxxx>; Sharma, Shashank <shashank.sharma@xxxxxxxxx>; Jose Abreu <joabreu@xxxxxxxxxxxx>; dri-devel@xxxxxxxxxxxxxxxxxxxxx Subject: Re: [PATCH v2 2/3] drm/edid: Implement SCDC support detection On Mon, Dec 05, 2016 at 06:11:44PM +0100, Thierry Reding wrote: > On Mon, Dec 05, 2016 at 05:21:24PM +0100, Daniel Vetter wrote: > > On Mon, Dec 05, 2016 at 12:11:46PM +0100, Thierry Reding wrote: > > > On Mon, Dec 05, 2016 at 09:16:27AM +0100, Daniel Vetter wrote: > > > > On Mon, Dec 05, 2016 at 08:57:43AM +0100, Thierry Reding wrote: > > > > > On Sat, Dec 03, 2016 at 04:35:24AM +0000, Sharma, Shashank wrote: > > > > > > Hi Thierry, > > > > > > > > > > > > If you can please have a look on this patch, I had written one to parse HF-VSDB, which was covering SCDC detection too. > > > > > > https://patchwork.kernel.org/patch/9452259/ > > > > > > > > > > I think there had been pushback before about caching > > > > > capabilities from EDID, so from that point of view my patch is > > > > > more inline with existing EDID parsing API. > > > > > > > > Hm, where was that pushback? We do have a bit a mess between > > > > explicitly parsing stuff (e.g. eld) and stuffing parsed data into drm_display_info. > > > > > > You did object to a very similar patch some time ago that did a > > > similar thing for DPCD stuff. And also Villa had commented on an > > > earlier patch from Jose about concerns of bloating core structures: > > > > > > https://patchwork.freedesktop.org/patch/104806/ > > > > DPCD I complained about because somehow we ended up with 2 sets of > > helpers, one filling a struct and the others returning directly. I > > objected to the fact that there's 2 (and imo your patch duplicated > > even more), not that I think one approach is clearly inferior to the other. > > My recollection is that I had proposed that I do the work of > transitioning users of the parsers to the cached information but you > had said that it wasn't worth the churn and that we should just go > with the existing scheme of passing around the DPCD buffer and > extending the parsers as necessary. Hm, I guess it wasn't clear to me that you've offered to do all the conversions. Doing that would be awesome I think (but quite a bit of work), and if we bother with it, parsing into a struct is imo the better idea long-term. > From that I inferred that the same would be true for EDID and since we > already have a couple of helpers that operate on struct edid * and > which return features, continuing that scheme was preferred. > > Anyway, I don't really care either way. Maybe you and Ville can duke > it out whether or not we want all of the fields parsed, irrespective > of whether or not they will be used. Then I'll go with whatever you decide. > > > Demanding that there's some real users is also a valid point. > > > > > > I think long-term stuffing it into drm_display_info is probably > > > > better, since then we only have 1 interaction point between the > > > > probe code and the atomic_check code. That should be useful for > > > > eventually fixing the lack of locking between the two, if I ever > > > > get around to that ;-) > > > > > > I don't really have objections to caching the results of parsing, > > > it's what I had proposed and what seemed most natural back when I > > > was working on the DPCD helpers. But if we now agree that this is > > > the preferred way to do things, then we should at least agree that > > > it applies to all areas for the sake of consistency. > > > > > > Also, it might be worth looking into improving the structures, and > > > maybe adding new ones to order things more conveniently or at > > > least group them in some logical way. In my opinion some of our > > > data structures are becoming somewhat... unwieldy. > > > > We're pretty good at consuming fairly invasive refactorings in drm-misc. > > So it just boils down to get some agreement on what things should > > look like (+1 from my side to parsing stuff into structs as a > > general idea), and then massaging all the existing users of the > > "wrong" interface using cocci and sed. > > > > Unfortunately "just" ;-) > > I think by now it would be useful to have a nested structure within > struct drm_display_info that contains HDMI specific bits. We already > have a number of candidates that could be extracted into such a > structure (drm_detect_hdmi_monitor(), drm_detect_monitor_audio(), > drm_rgb_quant_range_selectable(), ...). > > Another possibility would be to subclass struct drm_display_info, as > in: > > struct drm_hdmi_info { > struct drm_display_info display; > > /* HDMI specific information */ > ... > }; > > Or yet another would be to create struct drm_hdmi_info as a separate > structure and provide a helper which will extract the necessary info > from the EDID. Drivers could then store that in driver-private data > whereas struct drm_display_info could be reduced to the generic bits > that it used to have. I think nested drm_hdmi_info within drm_display_info sounds like a fine idea. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
