FAILED: patch "[PATCH] drm/amdgpu: publish IH enabled before PSP programs IH_RB_CNTL" failed to apply to 5.15-stable tree

[Sasha Levin <sashal@kernel.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 9d550dd1a3b4b96da49f3560a84b5c2413a88cd3
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261109202411-failed-5.15-9d550dd1a3b4@kernel.org' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From 9d550dd1a3b4b96da49f3560a84b5c2413a88cd3 Mon Sep 17 00:00:00 2001
From: Milan Milicevic <Milan.Milicevic@amd.com>
Date: Wed, 28 Oct 2026 15:31:55 +0100
Subject: [PATCH] drm/amdgpu: publish IH enabled before PSP programs IH_RB_CNTL

On SR-IOV, programming IH_RB_CNTL through PSP is slow enough for the
first MSI to arrive before ih->enabled is set. amdgpu_ih_process()
then drops the interrupt, rptr stays at 0, and RPTR_REARM never
generates another edge, so every ring hits the fence fallback timer.

Set ih->enabled before psp_reg_program() on the indirect IH path for
Navi10 and IH v6.0, and clear it if programming fails.

Signed-off-by: Danijel Slivka <Danijel.Slivka@amd.com>
Signed-off-by: Milan Milicevic <Milan.Milicevic@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit b2f9434f9d17c94798e8d8957af3adc4a9949016)
Cc: stable@vger.kernel.org
---
 drivers/gpu/drm/amd/amdgpu/ih_v6_0.c   | 13 ++++++++++++-
 drivers/gpu/drm/amd/amdgpu/navi10_ih.c | 13 ++++++++++++-
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/ih_v6_0.c b/drivers/gpu/drm/amd/amdgpu/ih_v6_0.c
index 8dee486496501..478b7169f44c2 100644
--- a/drivers/gpu/drm/amd/amdgpu/ih_v6_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/ih_v6_0.c
@@ -168,8 +168,19 @@ static int ih_v6_0_toggle_ring_interrupts(struct amdgpu_device *adev,
 		tmp = REG_SET_FIELD(tmp, IH_RB_CNTL, ENABLE_INTR, (enable ? 1 : 0));
 
 	if (amdgpu_sriov_vf(adev) && amdgpu_sriov_reg_indirect_ih(adev)) {
-		if (psp_reg_program(&adev->psp, ih_regs->psp_reg_id, tmp))
+		/*
+		 * PSP programming of IH_RB_CNTL is slow enough for MSI to
+		 * arrive before this call returns. Publish ih->enabled first
+		 * so amdgpu_ih_process() consumes that IV and rearms.
+		 */
+		if (enable) {
+			ih->enabled = true;
+			smp_wmb();
+		}
+		if (psp_reg_program(&adev->psp, ih_regs->psp_reg_id, tmp)) {
+			ih->enabled = false;
 			return -ETIMEDOUT;
+		}
 	} else {
 		WREG32(ih_regs->ih_rb_cntl, tmp);
 	}
diff --git a/drivers/gpu/drm/amd/amdgpu/navi10_ih.c b/drivers/gpu/drm/amd/amdgpu/navi10_ih.c
index ab12ce8da3dc3..fa5148ae526de 100644
--- a/drivers/gpu/drm/amd/amdgpu/navi10_ih.c
+++ b/drivers/gpu/drm/amd/amdgpu/navi10_ih.c
@@ -194,8 +194,19 @@ static int navi10_ih_toggle_ring_interrupts(struct amdgpu_device *adev,
 		tmp = REG_SET_FIELD(tmp, IH_RB_CNTL, ENABLE_INTR, (enable ? 1 : 0));
 
 	if (amdgpu_sriov_vf(adev) && amdgpu_sriov_reg_indirect_ih(adev)) {
-		if (psp_reg_program(&adev->psp, ih_regs->psp_reg_id, tmp))
+		/*
+		 * PSP programming of IH_RB_CNTL is slow enough for MSI to
+		 * arrive before this call returns. Publish ih->enabled first
+		 * so amdgpu_ih_process() consumes that IV and rearms.
+		 */
+		if (enable) {
+			ih->enabled = true;
+			smp_wmb();
+		}
+		if (psp_reg_program(&adev->psp, ih_regs->psp_reg_id, tmp)) {
+			ih->enabled = false;
 			return -ETIMEDOUT;
+		}
 	} else {
 		WREG32(ih_regs->ih_rb_cntl, tmp);
 	}
-- 
2.53.0