linux-kernel - [PATCH 06/17] drm/msm: Add an ftrace for gpu register access

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Message-Id: <20250720-ifpc-support-v1-6-9347aa5bcbd6@oss.qualcomm.com>
Date: Sun, 20 Jul 2025 17:46:07 +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>
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 06/17] drm/msm: Add an ftrace for gpu register access

With IFPC, there is a probability of accessing a GX domain register when
it is collapsed, which leads to gmu fence errors. To debug this, we need
to trace every gpu register accesses and identify the one just before a
gmu fence error. So, add an ftrace to track all gpu register accesses.

Signed-off-by: Akhil P Oommen <akhilpo@....qualcomm.com>
---
 drivers/gpu/drm/msm/msm_gpu.h       |  8 ++++++++
 drivers/gpu/drm/msm/msm_gpu_trace.h | 12 ++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index 5bf7cd985b9c50e38468fed695234f787919a8aa..a0a0cf9efb3a8035a80cbbbf30ad294a72ccbd48 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -16,6 +16,7 @@
 
 #include "msm_drv.h"
 #include "msm_fence.h"
+#include "msm_gpu_trace.h"
 #include "msm_ringbuffer.h"
 #include "msm_gem.h"
 
@@ -555,16 +556,19 @@ struct msm_gpu_state {
 
 static inline void gpu_write(struct msm_gpu *gpu, u32 reg, u32 data)
 {
+	trace_msm_gpu_regaccess(reg);
 	writel(data, gpu->mmio + (reg << 2));
 }
 
 static inline u32 gpu_read(struct msm_gpu *gpu, u32 reg)
 {
+	trace_msm_gpu_regaccess(reg);
 	return readl(gpu->mmio + (reg << 2));
 }
 
 static inline void gpu_rmw(struct msm_gpu *gpu, u32 reg, u32 mask, u32 or)
 {
+	trace_msm_gpu_regaccess(reg);
 	msm_rmw(gpu->mmio + (reg << 2), mask, or);
 }
 
@@ -586,7 +590,9 @@ static inline u64 gpu_read64(struct msm_gpu *gpu, u32 reg)
 	 * when the lo is read, so make sure to read the lo first to trigger
 	 * that
 	 */
+	trace_msm_gpu_regaccess(reg);
 	val = (u64) readl(gpu->mmio + (reg << 2));
+	trace_msm_gpu_regaccess(reg+1);
 	val |= ((u64) readl(gpu->mmio + ((reg + 1) << 2)) << 32);
 
 	return val;
@@ -594,8 +600,10 @@ static inline u64 gpu_read64(struct msm_gpu *gpu, u32 reg)
 
 static inline void gpu_write64(struct msm_gpu *gpu, u32 reg, u64 val)
 {
+	trace_msm_gpu_regaccess(reg);
 	/* Why not a writeq here? Read the screed above */
 	writel(lower_32_bits(val), gpu->mmio + (reg << 2));
+	trace_msm_gpu_regaccess(reg+1);
 	writel(upper_32_bits(val), gpu->mmio + ((reg + 1) << 2));
 }
 
diff --git a/drivers/gpu/drm/msm/msm_gpu_trace.h b/drivers/gpu/drm/msm/msm_gpu_trace.h
index 7f863282db0d7812c8fd53b3f1fc0cd5635028ba..193dc9c8a7705c8988b8c4b60aa78a74e00af932 100644
--- a/drivers/gpu/drm/msm/msm_gpu_trace.h
+++ b/drivers/gpu/drm/msm/msm_gpu_trace.h
@@ -205,6 +205,18 @@ TRACE_EVENT(msm_gpu_preemption_irq,
 		TP_printk("preempted to %u", __entry->ring_id)
 );
 
+TRACE_EVENT(msm_gpu_regaccess,
+		TP_PROTO(u32 offset),
+		TP_ARGS(offset),
+		TP_STRUCT__entry(
+			__field(u32, offset)
+			),
+		TP_fast_assign(
+			__entry->offset = offset;
+			),
+		TP_printk("offset=0x%x", __entry->offset)
+);
+
 #endif
 
 #undef TRACE_INCLUDE_PATH

-- 
2.50.1