Reading back the remapped HDP flush register seems to cause
problems on some platforms. All we need is a read, so read back
the memcfg register.
Fixes: f756dbac1ce1 ("drm/amdgpu/hdp5.2: do a posting read when flushing HDP")
Reported-by: Alexey Klimov <[email protected]>
Link: https://lists.freedesktop.org/archives/amd-gfx/2025-April/123150.html
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4119
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3908
Signed-off-by: Alex Deucher <[email protected]>
---
drivers/gpu/drm/amd/amdgpu/hdp_v5_2.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/hdp_v5_2.c
b/drivers/gpu/drm/amd/amdgpu/hdp_v5_2.c
index fcb8dd2876bcc..40940b4ab4007 100644
--- a/drivers/gpu/drm/amd/amdgpu/hdp_v5_2.c
+++ b/drivers/gpu/drm/amd/amdgpu/hdp_v5_2.c
@@ -33,7 +33,17 @@ static void hdp_v5_2_flush_hdp(struct amdgpu_device *adev,
if (!ring || !ring->funcs->emit_wreg) {
WREG32_NO_KIQ((adev->rmmio_remap.reg_offset +
KFD_MMIO_REMAP_HDP_MEM_FLUSH_CNTL) >> 2,
0);
- RREG32_NO_KIQ((adev->rmmio_remap.reg_offset +
KFD_MMIO_REMAP_HDP_MEM_FLUSH_CNTL) >> 2);
+ if (amdgpu_sriov_vf(adev)) {
+ /* this is fine because SR_IOV doesn't remap the
register */
+ RREG32_NO_KIQ((adev->rmmio_remap.reg_offset +
KFD_MMIO_REMAP_HDP_MEM_FLUSH_CNTL) >> 2);
+ } else {
+ /* We just need to read back a register to post the
write.
+ * Reading back the remapped register causes problems on
+ * some platforms so just read back the memory size
register.
+ */
+ if (adev->nbio.funcs->get_memsize)
+ adev->nbio.funcs->get_memsize(adev);
+ }
} else {
amdgpu_ring_emit_wreg(ring,
(adev->rmmio_remap.reg_offset +
KFD_MMIO_REMAP_HDP_MEM_FLUSH_CNTL) >> 2,
--
2.49.0
