linux-kernel - [PATCH 5.12 052/242] drm/amdgpu: remove unsafe optimization to drop preamble ib

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Message-Id: <20210715182601.499183124@linuxfoundation.org>
Date:   Thu, 15 Jul 2021 20:36:54 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jiansong Chen <Jiansong.Chen@....com>,
        Hawking Zhang <Hawking.Zhang@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.12 052/242] drm/amdgpu: remove unsafe optimization to drop preamble ib

From: Jiansong Chen <Jiansong.Chen@....com>

[ Upstream commit 7d9c70d23550eb86a1bec1954ccaa8d6ec3a3328 ]

Take the situation with gfxoff, the optimization may cause
corrupt CE ram contents. In addition emit_cntxcntl callback
has similar optimization which firmware can handle properly
even for power feature.

Signed-off-by: Jiansong Chen <Jiansong.Chen@....com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
index 97c11aa47ad0..7892958d5f59 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
@@ -131,7 +131,7 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
 	struct amdgpu_device *adev = ring->adev;
 	struct amdgpu_ib *ib = &ibs[0];
 	struct dma_fence *tmp = NULL;
-	bool skip_preamble, need_ctx_switch;
+	bool need_ctx_switch;
 	unsigned patch_offset = ~0;
 	struct amdgpu_vm *vm;
 	uint64_t fence_ctx;
@@ -228,7 +228,6 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
 	if (need_ctx_switch)
 		status |= AMDGPU_HAVE_CTX_SWITCH;
 
-	skip_preamble = ring->current_ctx == fence_ctx;
 	if (job && ring->funcs->emit_cntxcntl) {
 		status |= job->preamble_status;
 		status |= job->preemption_status;
@@ -246,14 +245,6 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
 	for (i = 0; i < num_ibs; ++i) {
 		ib = &ibs[i];
 
-		/* drop preamble IBs if we don't have a context switch */
-		if ((ib->flags & AMDGPU_IB_FLAG_PREAMBLE) &&
-		    skip_preamble &&
-		    !(status & AMDGPU_PREAMBLE_IB_PRESENT_FIRST) &&
-		    !amdgpu_mcbp &&
-		    !amdgpu_sriov_vf(adev)) /* for SRIOV preemption, Preamble CE ib must be inserted anyway */
-			continue;
-
 		if (job && ring->funcs->emit_frame_cntl) {
 			if (secure != !!(ib->flags & AMDGPU_IB_FLAGS_SECURE)) {
 				amdgpu_ring_emit_frame_cntl(ring, false, secure);
-- 
2.30.2