radeon_cursor

[Vladimir Dergachev]

Hi all,

  I've been looking at ati/radeon_cursor.c and I've been having problems 
understanding how the driver ensures that the video engine is idle which 
swapping cursor.

  My understanding is that the cursor update runs in a separate thread (as 
the mouse still works when the server is otherwise locked up).

  However, CURSOR_SWAPPING_START() does not contain anything to wait for 
engine idle, which seems to imply that we can be writing cursor data while 
the engine is busy.

  This is indeed what I see with R300 - when glxtest is running full speed
I get a lockup when mouse crosses window boundaries (this involves 
changing cursor shape because of window manager).

  On the other hand, I am aware that this does not appear to cause lockup 
in plain Radeons and R200 cards.

  Would anyone know why ?

                        thank you !

                             Vladimir Dergachev