From: jsg <jsg@openbsd.org>
Date: Mon, 5 Aug 2024 02:42:47 +0000 (+0000)
Subject: drm/amdgpu/sdma5.2: Update wptr registers as well as doorbell
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=f61f9b4df6522f1134099e5785f14bd8c3a3cd02;p=openbsd

drm/amdgpu/sdma5.2: Update wptr registers as well as doorbell

From Alex Deucher
9d74e50098492e89f319ac6922db3c2062f69340 in linux-6.6.y/6.6.44
a03ebf116303e5d13ba9a2b65726b106cb1e96f6 in mainline linux
---

diff --git a/sys/dev/pci/drm/amd/amdgpu/sdma_v5_2.c b/sys/dev/pci/drm/amd/amdgpu/sdma_v5_2.c
index ac3ae213155..61afab0d0fc 100644
--- a/sys/dev/pci/drm/amd/amdgpu/sdma_v5_2.c
+++ b/sys/dev/pci/drm/amd/amdgpu/sdma_v5_2.c
@@ -188,6 +188,14 @@ static void sdma_v5_2_ring_set_wptr(struct amdgpu_ring *ring)
 		DRM_DEBUG("calling WDOORBELL64(0x%08x, 0x%016llx)\n",
 				ring->doorbell_index, ring->wptr << 2);
 		WDOORBELL64(ring->doorbell_index, ring->wptr << 2);
+		/* SDMA seems to miss doorbells sometimes when powergating kicks in.
+		 * Updating the wptr directly will wake it. This is only safe because
+		 * we disallow gfxoff in begin_use() and then allow it again in end_use().
+		 */
+		WREG32(sdma_v5_2_get_reg_offset(adev, ring->me, mmSDMA0_GFX_RB_WPTR),
+		       lower_32_bits(ring->wptr << 2));
+		WREG32(sdma_v5_2_get_reg_offset(adev, ring->me, mmSDMA0_GFX_RB_WPTR_HI),
+		       upper_32_bits(ring->wptr << 2));
 	} else {
 		DRM_DEBUG("Not using doorbell -- "
 				"mmSDMA%i_GFX_RB_WPTR == 0x%08x "
@@ -1666,6 +1674,10 @@ static void sdma_v5_2_ring_begin_use(struct amdgpu_ring *ring)
 	 * but it shouldn't hurt for other parts since
 	 * this GFXOFF will be disallowed anyway when SDMA is
 	 * active, this just makes it explicit.
+	 * sdma_v5_2_ring_set_wptr() takes advantage of this
+	 * to update the wptr because sometimes SDMA seems to miss
+	 * doorbells when entering PG.  If you remove this, update
+	 * sdma_v5_2_ring_set_wptr() as well!
 	 */
 	amdgpu_gfx_off_ctrl(adev, false);
 }