[PATCH 1/2] Revert "drm: Add and handle new aspect ratios in DRM layer"
Daniel Vetter
daniel at ffwll.ch
Tue Nov 15 08:51:35 UTC 2016
On Mon, Nov 14, 2016 at 10:26:08PM +0530, Sharma, Shashank wrote:
> On 11/14/2016 10:15 PM, Ville Syrjälä wrote:
> > 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.
>
> In any case, I guess addition of a cap for aspect ratio should fix the
> current objections for this implementation.
>
> And I will keep it 0 by default, so that no aspect ratio information is
> added until userspace sets the cap to 1 on its own.
Note that cap = needs new userspace.
-Daniel
>
>
> Regards
>
> Shashank
>
> > > 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
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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