From 1824e914e291a2e638828896acf8bc008b1018a1 Mon Sep 17 00:00:00 2001 From: Alex Deucher Date: Wed, 30 Apr 2025 12:46:56 -0400 Subject: [PATCH] drm/amdgpu/hdp5: use memcfg register to post the write for HDP flush commit 0e33e0f339b91eecd9558311449a3d1e728722d4 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: cf424020e040 ("drm/amdgpu/hdp5.0: 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 a5cb344033c7598762e89255e8ff52827abb57a4) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/amd/amdgpu/hdp_v5_0.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/amdgpu/hdp_v5_0.c b/drivers/gpu/drm/amd/amdgpu/hdp_v5_0.c index d3962d469088..40705e13ca56 100644 --- a/drivers/gpu/drm/amd/amdgpu/hdp_v5_0.c +++ b/drivers/gpu/drm/amd/amdgpu/hdp_v5_0.c @@ -33,7 +33,12 @@ static void hdp_v5_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); }