drm/etnaviv: print MMU exception cause

The MMU tells us the fault status. While the raw register value is
already printed, it's a bit more user friendly to translate the
fault reasons into human readable format.
Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

drivers/gpu/drm/etnaviv/etnaviv_gpu.c

@@ -1454,6 +1454,15 @@ static void sync_point_worker(struct work_struct *work)
 
 static void dump_mmu_fault(struct etnaviv_gpu *gpu)
 {
+	static const char *fault_reasons[] = {
+		"slave not present",
+		"page not present",
+		"write violation",
+		"out of bounds",
+		"read security violation",
+		"write security violation",
+	};
+
 	u32 status_reg, status;
 	int i;
 
@@ -1466,18 +1475,25 @@ static void dump_mmu_fault(struct etnaviv_gpu *gpu)
 	dev_err_ratelimited(gpu->dev, "MMU fault status 0x%08x\n", status);
 
 	for (i = 0; i < 4; i++) {
+		const char *reason = "unknown";
 		u32 address_reg;
+		u32 mmu_status;
 
-		if (!(status & (VIVS_MMUv2_STATUS_EXCEPTION0__MASK << (i * 4))))
+		mmu_status = (status >> (i * 4)) & VIVS_MMUv2_STATUS_EXCEPTION0__MASK;
+		if (!mmu_status)
 			continue;
 
+		if ((mmu_status - 1) < ARRAY_SIZE(fault_reasons))
+			reason = fault_reasons[mmu_status - 1];
+
 		if (gpu->sec_mode == ETNA_SEC_NONE)
 			address_reg = VIVS_MMUv2_EXCEPTION_ADDR(i);
 		else
 			address_reg = VIVS_MMUv2_SEC_EXCEPTION_ADDR;
 
-		dev_err_ratelimited(gpu->dev, "MMU %d fault addr 0x%08x\n", i,
-				    gpu_read(gpu, address_reg));
+		dev_err_ratelimited(gpu->dev,
+				    "MMU %d fault (%s) addr 0x%08x\n",
+				    i, reason, gpu_read(gpu, address_reg));
 	}
 }