drm/radeon/kms: fix possible sigbus in evergreen accel code

Not upstream in Linus's tree as it was fixed by a much more intrusive
patch in a different manner, commit c919b371cb734f42b11

2.6.35 and 2.6.36 do not contain blit support for evergreen
asics so if they use unmappable vram, you can end up with an
unreachable buffer address.  This should not be applied to drm-next
as that tree already contains evergreen blit support.  This should
only be applied to the 2.6.35 and 2.6.36 stable trees.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=30188

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
index 0bfb83638a5d6819fd9ae13e561b5a23622631e5..82cc369a85ec56b0afda6e4532e7038dbfe01a2e 100644 (file)
--- a/drivers/gpu/drm/radeon/evergreen.c
+++ b/drivers/gpu/drm/radeon/evergreen.c
@@ -1389,6 +1389,8 @@ int evergreen_mc_init(struct radeon_device *rdev)
        rdev->mc.mc_vram_size = RREG32(CONFIG_MEMSIZE) * 1024 * 1024;
        rdev->mc.real_vram_size = RREG32(CONFIG_MEMSIZE) * 1024 * 1024;
        rdev->mc.visible_vram_size = rdev->mc.aper_size;
+       /* limit it to the aperture size for now as there is no blit support in 2.6.35/36*/
+       rdev->mc.real_vram_size = rdev->mc.visible_vram_size;
        r600_vram_gtt_location(rdev, &rdev->mc);
        radeon_update_bandwidth_info(rdev);