On Don, 2012-02-02 at 10:26 -0500, Ilija Hadzic wrote:
Evergreen and NI blit copy was broken if the buffer maps to a rectangle whose one dimension is 16384 (max dimension allowed by these chips). In the mainline kernel, the problem is exposed only when buffers are very large (1G), but it's still a problem. The problem could be exposed for smaller buffers if anyone modifies the algorithm for rectangle construction in r600_blit_create_rect() (the reason why someone would modify that algorithm is to tune the performance of buffer moves).
The root cause was in i2f() function which only operated on range between 0 and 16383. Fix this by extending the range of i2f() function to 0 to 32767.
While at it improve the function so that the range can be easily extended in the future (if it becomes necessary), cleanup lines over 80 characters, and replace in-line comments with one strategic comment that explains the crux of the function.
Credits to michel@daenzer.net for pointing out the root cause of the bug.
v2: Fix I2F_MAX_INPUT constant definition goof and warn only once if input argument is out of range. Edit the comment a little bit to avoid some linguistic confusion and make it look better in general.
Signed-off-by: Ilija Hadzic ihadzic@research.bell-labs.com
Reviewed-by: Michel Dänzer michel@daenzer.net