[Bug 2506] New: Radeon: Hardware Cursor messes up TV out.

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https://bugs.freedesktop.org/show_bug.cgi?id=2506          
     
           Summary: Radeon: Hardware Cursor messes up TV out.
           Product: DRI
           Version: XOrg CVS
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DDX drivers
        AssignedTo: dri...@li...
        ReportedBy: ar...@if...


GPU: Radeon 7500 Mobile 32mb (IBM Thinkpad T41 model-num:2378-DLU)
X Server: X.org CVS Feburary 2nd, 2005
Basic Description: If a hardware cursor is used when TV out is enabled, the
Display on the TV gets corurpted.

I have known of this problem since June of last year. I have not been able to
test it on another machines as I lack access to another maching with a radeon
running linux. The problem is reproducable every time on my own machine.

To reproduce, simply start X with a hardware cursor (option "SWCURSOR" disabled)
and enable TV by means of enabling "VGAAccess", "BIOSHotKeys" and running
'atitvout -f t' when X is running. The -f option on atitvout (force ATI-Rage)
mode is nessisary as the regular R126/Radeon mode '-r' fails. The display will
appear on the TV as normal, except the cursor will be a black rectangle that is
about 48-ish pixels square. The black square contains some series of pixels that
are transparent or random colours. Apart from that the display will be fine
until the cursor is moved a certain distance. Once the cursor is moved a regular
distance the image on the TV gets currupted. It appears to me as if the gamma
has been increased sevearly and then the brightness of each pixel modularly
divided (Think that is the correct term, you know how 20 modularly divided by 16
 is 4 and 34 modularly divided by 16 is 2 (20 - 16 = 4, 34 - 2(16) = 2) so that
realy bright areas of the screen are black. I beleive this is because of a
hardware gamma bug, as when switched back to the LDC (atitvout -f l) the image
on the LCD looks to have had the gamma on it turned up. The bug is not dependant
on 3D accelleration (NOACCEL has no effect) and xgamma doesn't do anything to
fix the problem. 2D, 3D and XV out are all effected. The display is recoverable
by restarting X, but the bug will still occur if TV-out and hardware cursor are
still used. The bug produces no output to the X log.

Not really a major bug, but still a bit anoying. Can be solved by using a
software cursor when TV-out is needed. My guess (only a guess, I've never seen
the code, and I probably wouldn't understand it) is that somehow the gamma is
increased when the hardware cursor is drawn on the tv-out, and the TV-out DAC
can't handle such large numbers, so the top bits get's 'clipped' (my guess is a
buffer overflow) and the remaining bits are used as the brightness (per pixel
here.) Thanks for any help.          
     
     
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