drm/panfrost: Don't try to map on error faults

If the exception type isn't a translation fault, don't try to map and
instead go straight to a terminal fault.

Otherwise, we can get flooded by kernel warnings and further faults.

Fixes: 187d2929 ("drm/panfrost: Add support for GPU heap allocations")
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200212202236.13095-1-robh@kernel.org

drivers/gpu/drm/panfrost/panfrost_mmu.c

@@ -601,17 +601,11 @@ static irqreturn_t panfrost_mmu_irq_handler_thread(int irq, void *data)
 		source_id = (fault_status >> 16);
 
 		/* Page fault only */
-		if ((status & mask) == BIT(i)) {
-			WARN_ON(exception_type < 0xC1 || exception_type > 0xC4);
-
+		ret = -1;
+		if ((status & mask) == BIT(i) && (exception_type & 0xF8) == 0xC0)
 			ret = panfrost_mmu_map_fault_addr(pfdev, i, addr);
-			if (!ret) {
-				mmu_write(pfdev, MMU_INT_CLEAR, BIT(i));
-				status &= ~mask;
-				continue;
-			}
-		}
 
+		if (ret)
 			/* terminal fault, print info about the fault */
 			dev_err(pfdev->dev,
 				"Unhandled Page fault in AS%d at VA 0x%016llX\n"