linux-kernel - [PATCH v2 08/16] drm/msm/a6xx: Set Keep-alive votes to block IFPC

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250908-ifpc-support-v2-8-631b1080bf91@oss.qualcomm.com>
Date: Mon, 08 Sep 2025 13:57:01 +0530
From: Akhil P Oommen <akhilpo@....qualcomm.com>
To: Rob Clark <robin.clark@....qualcomm.com>, Sean Paul <sean@...rly.run>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Dmitry Baryshkov <lumag@...nel.org>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Jessica Zhang <jessica.zhang@....qualcomm.com>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Antonino Maniscalco <antomani103@...il.com>,
        Neil Armstrong <neil.armstrong@...aro.org>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Akhil P Oommen <akhilpo@....qualcomm.com>
Subject: [PATCH v2 08/16] drm/msm/a6xx: Set Keep-alive votes to block IFPC

Set Keepalive votes at appropriate places to block IFPC power collapse
until we access all the required registers. This is required during gpu
IRQ handling and also during preemption.

Signed-off-by: Akhil P Oommen <akhilpo@....qualcomm.com>
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 26 +++++++++++++++++---------
 drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 20 ++++++++++++++++++++
 2 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index a63dad80ef461da45d5c41a042ed4f19d8282ef5..33a26bbd245ff49784bf1219a584936b4caa62b6 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -1771,8 +1771,6 @@ static void a6xx_cp_hw_err_irq(struct msm_gpu *gpu)
 
 static void a6xx_fault_detect_irq(struct msm_gpu *gpu)
 {
-	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
-	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
 	struct msm_ringbuffer *ring = gpu->funcs->active_ring(gpu);
 
 	/*
@@ -1784,13 +1782,6 @@ static void a6xx_fault_detect_irq(struct msm_gpu *gpu)
 	if (gpu_read(gpu, REG_A6XX_RBBM_STATUS3) & A6XX_RBBM_STATUS3_SMMU_STALLED_ON_FAULT)
 		return;
 
-	/*
-	 * Force the GPU to stay on until after we finish
-	 * collecting information
-	 */
-	if (!adreno_has_gmu_wrapper(adreno_gpu))
-		gmu_write(&a6xx_gpu->gmu, REG_A6XX_GMU_GMU_PWR_COL_KEEPALIVE, 1);
-
 	DRM_DEV_ERROR(&gpu->pdev->dev,
 		"gpu fault ring %d fence %x status %8.8X rb %4.4x/%4.4x ib1 %16.16llX/%4.4x ib2 %16.16llX/%4.4x\n",
 		ring ? ring->id : -1, ring ? ring->fctx->last_fence : 0,
@@ -1829,9 +1820,24 @@ static void a7xx_sw_fuse_violation_irq(struct msm_gpu *gpu)
 	}
 }
 
+static void a6xx_gpu_keepalive_vote(struct msm_gpu *gpu, bool on)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+
+	if (adreno_has_gmu_wrapper(adreno_gpu))
+		return;
+
+	gmu_write(&a6xx_gpu->gmu, REG_A6XX_GMU_GMU_PWR_COL_KEEPALIVE, on);
+}
+
 static irqreturn_t a6xx_irq(struct msm_gpu *gpu)
 {
 	struct msm_drm_private *priv = gpu->dev->dev_private;
+
+	/* Set keepalive vote to avoid power collapse after RBBM_INT_0_STATUS is read */
+	a6xx_gpu_keepalive_vote(gpu, true);
+
 	u32 status = gpu_read(gpu, REG_A6XX_RBBM_INT_0_STATUS);
 
 	gpu_write(gpu, REG_A6XX_RBBM_INT_CLEAR_CMD, status);
@@ -1868,6 +1874,8 @@ static irqreturn_t a6xx_irq(struct msm_gpu *gpu)
 	if (status & A6XX_RBBM_INT_0_MASK_CP_SW)
 		a6xx_preempt_irq(gpu);
 
+	a6xx_gpu_keepalive_vote(gpu, false);
+
 	return IRQ_HANDLED;
 }
 
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
index 10625ffbc4cfc26edc36efcf11dbb4efd55ab3e0..2ce073d1cf8cfd7c774918851de03d6e367e5625 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
@@ -136,6 +136,21 @@ static void preempt_disable_postamble(struct a6xx_gpu *a6xx_gpu)
 	a6xx_gpu->postamble_enabled = false;
 }
 
+/*
+ * Set preemption keepalive vote. Please note that this vote is different from the one used in
+ * a6xx_irq()
+ */
+static void a6xx_preempt_keepalive_vote(struct msm_gpu *gpu, bool on)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+
+	if (adreno_has_gmu_wrapper(adreno_gpu))
+		return;
+
+	gmu_write(&a6xx_gpu->gmu, REG_A6XX_GMU_PWR_COL_PREEMPT_KEEPALIVE, on);
+}
+
 void a6xx_preempt_irq(struct msm_gpu *gpu)
 {
 	uint32_t status;
@@ -176,6 +191,8 @@ void a6xx_preempt_irq(struct msm_gpu *gpu)
 
 	set_preempt_state(a6xx_gpu, PREEMPT_NONE);
 
+	a6xx_preempt_keepalive_vote(gpu, false);
+
 	trace_msm_gpu_preemption_irq(a6xx_gpu->cur_ring->id);
 
 	/*
@@ -302,6 +319,9 @@ void a6xx_preempt_trigger(struct msm_gpu *gpu)
 
 	spin_unlock_irqrestore(&ring->preempt_lock, flags);
 
+	/* Set the keepalive bit to keep the GPU ON until preemption is complete */
+	a6xx_preempt_keepalive_vote(gpu, true);
+
 	a6xx_fenced_write(a6xx_gpu,
 		REG_A6XX_CP_CONTEXT_SWITCH_SMMU_INFO, a6xx_gpu->preempt_smmu_iova[ring->id],
 		BIT(1), true);

-- 
2.50.1