[PATCH 1/2] Revert "drm: Add and handle new aspect ratios in DRM layer"
Ville Syrjälä
ville.syrjala at linux.intel.com
Mon Nov 14 16:45:18 UTC 2016
On Mon, Nov 14, 2016 at 10:12:04PM +0530, Sharma, Shashank wrote:
> Regards
>
> Shashank
>
>
> On 11/14/2016 9:50 PM, Ville Syrjälä wrote:
> > On Mon, Nov 14, 2016 at 09:37:18PM +0530, Sharma, Shashank wrote:
> >> Regards
> >>
> >> Shashank
> >>
> >>
> >> On 11/14/2016 9:19 PM, Ville Syrjälä wrote:
> >>> On Mon, Nov 14, 2016 at 08:14:34PM +0530, Sharma, Shashank wrote:
> >>>> Regards
> >>>> Shashank
> >>>>> the revert:
> >>>>>
> >>>>> HDMI2 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 700mm x 390mm
> >>>>> - 1920x1080 60.00*+
> >>>>> - 1920x1080i 60.00 50.00
> >>>>> + 1920x1080 60.00*+ 50.00 59.94 30.00 25.00 24.00 29.97 23.98
> >>>>> + 1920x1080i 60.00 50.00 59.94
> >>>>> 1600x1200 60.00
> >>>>> 1680x1050 59.88
> >>>>> 1280x1024 75.02 60.02
> >>>>> @@ -13,30 +13,29 @@
> >>>>> 1360x768 60.02
> >>>>> 1280x800 59.91
> >>>>> 1152x864 75.00
> >>>>> - 1280x720 60.00 50.00
> >>>>> + 1280x720 60.00 50.00 59.94
> >>>>> 1024x768 75.03 70.07 60.00
> >>>>> 832x624 74.55
> >>>>> 800x600 72.19 75.00 60.32
> >>>>> - 640x480 75.00 72.81 66.67 59.94
> >>>>> + 720x576 50.00
> >>>>> + 720x480 60.00 59.94
> >>>>> + 640x480 75.00 72.81 66.67 60.00 59.94
> >>>>> 720x400 70.08
> >>>> None of these aspect ratios are new modes / new aspect ratios from HDMI
> >>>> 2.0/CEA-861-F
> >>>> These are the existing modes, and should be independent of reverted
> >>>> patches.
> >>> They're affected because your patches changed them by adding the aspect
> >>> ratio flags to them.
> >> Yes, But they are independent of reverted patch, which adds aspect ratio
> >> for HDMI 2.0 ratios (64:27 and 256:135)
> > The second patch had to be reverted so that the first patch would revert
> > cleanly.
> >
> >>>>> This was with sna, which does this:
> >>>>> #define KNOWN_MODE_FLAGS ((1<<14)-1)
> >>>>> if (mode->status == MODE_OK && kmode->flags & ~KNOWN_MODE_FLAGS)
> >>>>> mode->status = MODE_BAD; /* unknown flags => unhandled */
> >>>>> so all the modes with an aspect ratio just vanished.
> >>>>>
> >>>>> -modesetting and -ati on the other hand just copy over the unknown
> >>>>> bits into the xrandr mode structure, which sounds dubious at best:
> >>>>> mode->Flags = kmode->flags; //& FLAG_BITS;
> >>>>> I've not checked what damage it can actually cause.
> >>>>>
> >>>>>
> >>>>> It looks like a few modes disappeared from the kernel's mode list
> >>>>> as well, presumably because some cea modes in the list originated from
> >>>>> DTDs and whanot so they don't have an aspect ratio and that causes
> >>>>> add_alternate_cea_modes() to ignore them. So not populating an aspect
> >>>>> ratio for cea modes originating from a source other than
> >>>>> edid_cea_modes[] looks like another bug to me as well.
> >>>> I am writing a patch series to cap the aspect ratio implementation under
> >>>> a drm_cap_hdmi2_aspect_ratios
> >>>> This is how its going to work (inspired from the 2D/stereo series from
> >>>> damien L)
> >>>>
> >>>> - Add a new capability hdmi2_ar
> >>> It should be just a generic "expose aspect ratio flags to userspace?"
> >> Makes sense, in this way we can even revert the aspect_ratio property
> >> for HDMI connector, as discussed during
> >> the code review sessions of this patch series. In this way, when kernel
> >> will expose the aspect ratios, it will either
> >> do the aspect ratios as per EDID, or wont.
> >>>> - by default parsing the new hdmi 2.0 aspect ratio will be disabled
> >>>> under check of this cap
> >>>> - during bootup time, while initializing the display, a userspace can
> >>>> get_cap on the hdmi2_aspect_ratio
> >>>> - If it wants HDMI 2.0 aspect ratio support, it will set the cap, and
> >>>> kernel will expose these aspect ratios
> >>>>> Another bug I think might be the ordering of the modes with aspect ratio
> >>>>> specified. IIRC the spec says that the preferred aspect ratio should be
> >>>>> listed first in the EDID, but I don't think we preserve that ordering
> >>>>> in the final mode list. I guess we could fix that by somehow noting
> >>>>> which aspect ratio is preferred and sort based on that, or we try to
> >>>>> preserve the order from the EDID until we're ready to sort, and then do
> >>>>> the sorting with a stable algorithm.
> >>>> AFAIK The mode order and priority is decided and arranged in userspace,
> >>>> based on various factors like
> >>>> - preferred mode.
> >>>> - previously applied mode in previous sessions (like for android tvs)
> >>>> - Bigger h/w vs better refresh rate ?
> >>>> - Xserver applies its own algorithms to decide which mode should be
> >>>> shown first.
> >>> Xorg does sort on its own. But since it doesn't know anything about
> >>> aspect ratios and whatnot I wouldn't rely on that for anything. I
> >>> also wouldn't expect eg. wayland compositors to do their own sorting.
> >>> And yeah, looks like weston at least doesn't do any sorting whatsoever.
> >>>
> >>>> I dont think kernel needs to bother about it.
> >>> So I'm going to say that we in fact do need to bother.
> >>>
> >> IMHO, making policies for UI is not a part of kernel design, a UI
> >> manager (Hardware composed, X or Wayland) should take care of it, as
> >> they have access to much information (Like previously applied mode, user
> >> preference etc). When it comes to sorting of modes, the only general rule
> >> across drivers like FB, V4L2, I have seen is the first mode in the list
> >> should be preferred mode, which we are still keeping. And after that our
> >> probed_modes were
> >> anyways not sorted now, so it doesn't matter further.
> > Having userspace be responsible for sorting the aspect ratios would
> > perhaps require that userspace parses the EDID, which is pretty crazy.
> Why ?
> userspace has to just set cap for aspect ratio, and kernel can read
> EDID, parse the CEA block, populate the aspect ratios flags
> and add the modes (Just what this patch was doing, except the cap part)
> Once userspace has the getResources/getConnector call filled, it can
> access all the modes (with and without aspect) and do the sorting
> in any way it wants.
> > I guess it could try to deduce something from the physical aspect ratio
> > of the display, but I'm not sure that's quite what we want either.
> >
> > Also we already sort the modes in the kernel anyway, so it's not like
> > we'd be doing something new by also considering the aspect ratios.
> > I would at the very least want to avoid a totally random order between
> > modes that differ only by the aspect ratio.
> Path: get_connector -> probe_single_connector_mode -> drm_add_edid_modes
> Again, IMHO, we don't sort the modes in kernel, we populate modes in a
> particular order, which is:
> (From drm_edid.c::drm_add_edid_modes)
> ##############################################################
> /*
> * EDID spec says modes should be preferred in this order:
> * - preferred detailed mode
> * - other detailed modes from base block
> * - detailed modes from extension blocks
> * - CVT 3-byte code modes
> * - standard timing codes
> * - established timing codes
> * - modes inferred from GTF or CVT range information
> *
> * We get this pretty much right.
> *
> * XXX order for additional mode types in extension blocks?
> */
> num_modes += add_detailed_modes(connector, edid, quirks);
> num_modes += add_cvt_modes(connector, edid);
> num_modes += add_standard_modes(connector, edid);
> num_modes += add_established_modes(connector, edid);
> num_modes += add_cea_modes(connector, edid);
> num_modes += add_alternate_cea_modes(connector, edid);
> num_modes += add_displayid_detailed_modes(connector, edid);
> ###############################################################
>
> Here the modes are added in the connector, in the same order they are
> arranged into their respective blocks in EDID.
> But the order to read the block is a preferred order (no sorting).
>
> Now, in this patch series, we are adding aspect ratio information in
> edid_cea_modes db, which is going to affect only
> add_cea/alternate_cea_modes() call, and the modes accordingly.
> Please let me know if I misunderstood something here.
We explicitly sort the modes after this.
>
> Regards
> Shashank
> >> If X server doesn't know what to do with aspect ratio flags, it can
> >> chose not to set the cap, and if HWC knows, it can chose to set. This is
> >> the same situation as 2D stereo modes
> >> which are existing already.
> >>
> >> Regards
> >> Shashank
--
Ville Syrjälä
Intel OTC
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