| Message ID | 1310538502.4968.95.camel@pasglop (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c index 7e5c801..25b2dab 100644 --- a/drivers/gpu/drm/radeon/r600.c +++ b/drivers/gpu/drm/radeon/r600.c @@ -3300,6 +3300,10 @@ int r600_irq_process(struct radeon_device *rdev) if (!rdev->ih.enabled || rdev->shutdown) return IRQ_NONE; + /* No MSIs, need a dummy read to flush PCI DMAs */ + if (!rdev->msi_enabled) + RREG32(IH_RB_WPTR); + wptr = r600_get_ih_wptr(rdev); rptr = rdev->ih.rptr; DRM_DEBUG("r600_irq_process start: rptr %d, wptr %d\n", rptr, wptr);
When not using MSIs, there is no guarantee that DMA from the device has been fully flushed to point where it's visible to the CPU when taking an interrupt. To get this guarantee, we need to perform an MMIO read from the device, which will flush all outstanding DMAs from bridges between the device and the system. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> --- (resent adding dri-devel to the CC list to hit patchwork) drivers/gpu/drm/radeon/r600.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-)