[Intel-gfx] [PATCH-v2 0/3] drm/i915: interlaced mode support

[Peter Ross]

On Fri, Jan 20, 2012 at 10:24:03PM +1100, Peter Ross wrote:
> On Wed, Jan 18, 2012 at 12:55:15PM -0800, Jesse Barnes wrote:
> > On Wed, 18 Jan 2012 18:39:40 -0200
> > Paulo Zanoni <przanoni at gmail.com> wrote:
> > 
> > > Hi
> > > 
> > > 2012/1/18 Peter Ross <pross at xvid.org>:
> > > > This patch set enables enables interlaced mode output on
> > > > generation 3 and above chipsets.
> > > 
> > > I just tested that on HDMI.

Hey Paul, can you confirm which chipset you tested this on. I am keeping
track of who has had successes and fails in the patch comments.

I can also confirm that the patch also works on I915_G and I945_GME
chipsets using VGA out.

> > > The "interlace_allowed=1" patch seems fine: it made xrandr list more
> > > modes. But I believe patch 1 is still not correct. I tested that and
> > > instead of getting a 1920x1080 I got a 1920x1078 mode: vtotal, vblank
> > > and vsync were wrong. If you look at the patch, you'll see that the
> > > code has some "something -= 1" statements. I believe they could be
> > > wrong.
> > > 
> > > So I removed these lines and tested again... Now the mode is actually
> > > 1920x1080, but my monitor's OSD displays it as "1080p". So I also
> > > tested my TV and it reported "1080p at 25hz" too.
> > > 
> > > I guess we're still missing something... I'll try to debug.
> 
> Yep. I can confirm this problem too. With PATCH-v2, the output height
> is reduced by two lines. (I used a test bitmap to count the lines on CRT)
> 
> > Yeah for the interlaced case the -1 should be after the multiply, if
> > it's there at all...  would have to double check the docs.
> 
> The docs do suggest the timings need to be subtracted by one line.
> Performing the -1 after the *2 fixes the problem, and this has been tested
> on gen 3 and 4 chipsets.
> 
> When the -1 is removed altogether, the output is the visually identical
> to when the -1 is present. I'm erring on the side of keeping the -1,
> since that makes the implementation consistent with the documentation.

Another data point: The Intel G35 Display Driver for Windows XP does *not*
perform the -1. To determine this I dumped the G35 PCI memory region on
windows, and fed the dump file into intel_reg_dumper.

Cheers,

-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
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