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drm/radeon: Prevent too early kms-pageflips triggered by vblank.

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Since 3.16-rc1 we have this new failure:

When the userspace XOrg ddx schedules vblank events to
trigger deferred kms-pageflips, e.g., via the OML_sync_control
extension call glXSwapBuffersMscOML(), or if a glXSwapBuffers()
is called immediately after completion of a previous swapbuffers
call, e.g., in a tight rendering loop with minimal rendering,
it happens frequently that the pageflip ioctl() is executed
within the same vblank in which a previous kms-pageflip completed,
or - for deferred swaps - always one vblank earlier than requested
by the client app.

This causes premature pageflips and detection of failure by
the ddx, e.g., XOrg log warnings like...

"(WW) RADEON(1): radeon_dri2_flip_event_handler: Pageflip
completion event has impossible msc 201025 < target_msc 201026"

... and error/invalid return values of glXWaitForSbcOML() and
Intel_swap_events extension.

Reason is the new way in which kms-pageflips are programmed
since 3.16.

This commit changes the time window in which the hw can
execute pending programmed pageflips. Before, a pending flip
would get executed anywhere within the vblank interval. Now
a pending flip only gets executed at the leading edge of
vblank (start of front porch), making sure that a invocation
of the pageflip ioctl() within a given vblank interval will
only lead to pageflip completion in the following vblank.

Tested to death on a DCE-4 card.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Mario Kleiner
2014-07-03 03:45:02 +02:00
committed by Alex Deucher
parent 201bb62402
commit f53f81b257
4 changed files with 10 additions and 9 deletions
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5
drivers/gpu/drm/radeon/evergreen.c
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@@ -2642,8 +2642,9 @@ void evergreen_mc_resume(struct radeon_device *rdev, struct evergreen_mc_save *s
for (i = 0; i < rdev->num_crtc; i++) {
if (save->crtc_enabled[i]) {
tmp = RREG32(EVERGREEN_MASTER_UPDATE_MODE + crtc_offsets[i]);
if ((tmp & 0x3) != 0) {
tmp &= ~0x3;
if ((tmp & 0x7) != 3) {
tmp &= ~0x7;
tmp |= 0x3;
WREG32(EVERGREEN_MASTER_UPDATE_MODE + crtc_offsets[i], tmp);
}
tmp = RREG32(EVERGREEN_GRPH_UPDATE + crtc_offsets[i]);