From 03f108a718a7dfaeb9f0501fc0f5e34379172cba Mon Sep 17 00:00:00 2001 From: Alex Deucher Date: Wed, 30 Apr 2025 12:48:51 -0400 Subject: [PATCH] drm/amdgpu/hdp6: use memcfg register to post the write for HDP flush commit ca28e80abe4219c8f1a2961ae05102d70af6dc87 upstream. 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: abe1cbaec6cf ("drm/amdgpu/hdp6.0: do a posting read when flushing HDP") Reported-by: Alexey Klimov 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 Reviewed-by: Felix Kuehling Signed-off-by: Alex Deucher (cherry picked from commit 84141ff615951359c9a99696fd79a36c465ed847) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/amd/amdgpu/hdp_v6_0.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/amdgpu/hdp_v6_0.c b/drivers/gpu/drm/amd/amdgpu/hdp_v6_0.c index b6d71ec1debf..0d0c568f3839 100644 --- a/drivers/gpu/drm/amd/amdgpu/hdp_v6_0.c +++ b/drivers/gpu/drm/amd/amdgpu/hdp_v6_0.c @@ -33,7 +33,12 @@ static void hdp_v6_0_flush_hdp(struct amdgpu_device *adev, { if (!ring || !ring->funcs->emit_wreg) { WREG32((adev->rmmio_remap.reg_offset + KFD_MMIO_REMAP_HDP_MEM_FLUSH_CNTL) >> 2, 0); - RREG32((adev->rmmio_remap.reg_offset + KFD_MMIO_REMAP_HDP_MEM_FLUSH_CNTL) >> 2); + /* 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, 0); }