Hi all,
here's a summary of the experiments I have been doing.
* A RS690 can not render a full-HD image in the vertical blanking time
(@50Hz) but the engine should easily be able to render a full screen
when split in two halves. This is the assumption I'm now working with
and I feel confident about this.
* For testing purpose I'm rendering the source image (SD-TV) to a top
and bottom half, I'm using the full image scaled to half the height,
this eases comparison between the top and bottom segment. Before
rendering a segment I load the AVIVO_D1MODE_VLINE_START_END register and
issue a WAIT_UNTIL condition. These are some of the results:
(hope this table works :-/)
INV start
stop
Result
top half
bottom half
Set
Set
0
540
540
1080
WAIT+FE
WAIT+FE
tearing
tearing
top half
bottom half Set
Set
0
540
540
1080
FE
FE
tearing
tearing
top half
bottom half
0
540
540
1080
FE
FE
tearing
tearing
top half
bottom half Set
Set
540
0 1080
540 WAIT+FE
WAIT+FE
tearing
STABLE
top half
bottom half Set
Set
0
540
540
1080
RE
RE
tearing
STABLE
top half
bottom half
0
540
540
1080
RE
RE
tearing
STABLE
top half
bottom half
270
810
275
815
RE
RE
tearing
STABLE
top half
bottom half
540
1080
545
1085
RE
RE
tearing
STABLE
top half
bottom half
810
270
815
275
RE
RE
tearing
tearing
top half
bottom half
-
0
-
5
-
RE
tearing
STABLE
top half
bottom half
1080
-
1085
-
RE
-
tearing
tearing
top half
bottom half
0
-
5
-
RE
-
tearing
tearing
RE=RADEON_WAIT_RE_CRTC_VLINE
FE=RADEON_WAIT_FE_CRTC_VLINE
WAIT=RADEON_WAIT_CRTC_VLINE
* I can only get the bottom segment stable, top is always tearing. If I
scale the playback window to normal size (around 300 lines) the top
segment is tearing and the bottom segment is stable, this is independent
of the position of the window (top/bottom screen). The register values
for vertical blanking are fixed and do not scale with the window in this
test, very surprising.
* To see if the problem would be in the source data I added a 2ms delay
between the loading of the data in the framebuffer and the starting of
the rendering, this has no effect.
* I tried using 3 wait points (line 0, 270, 810). This is causing
mplayer to slow down video playback (complains too slow machine). Every
wait_until seems to be waiting for a full frame instead of the
sequential position in one frame.
* I tried putting all commands in the ring buffer to ensure execution in
the right order:
- Write VLINE_START_END, write WAIT_UNTIL
- Write Vertex data top segement
- Write R300_DC_FLUSH_3D
- Write VLINE_START_END, write WAIT_UNTIL
- Write Vertex data bottom segement
- Write R300_DC_FLUSH_3D
The documentation seems to suggest this is needed for R500 chips but
should have no effect on R300 chips. On the RS690 this has no effect,
identical results. There seems to be a minor bug in the current code
here where the space in the ringbuffer is allocated, not sure if this is
critical.
* The AVIVO_D1MODE_VLINE_START_END is doing something but it's not clear
what is happening. The register size also puzzles me, there seem to be
14 bits reserved for start and stop position (IRC blog) while the
vertical counter register only has 13 bits.
I'm really starting to run out of idea's here, any input would be very
appreciated. The system is intended as a HTPC connected to a full-HD LCD
but is pretty useless with the current performance. Fglrx drivers are
incredible unstable with full-HD and 64-bit platform and also do not
seem to resolve the tearing issue.
Christiaan.
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