[PATCH 3/4] drm/v3d: Don't clear MMU control bits on exception

[Stefan Wahren]

From: Phil Elwell <phil at raspberrypi.org>

MMU exception conditions are reported in the V3D_MMU_CTRL register as
write-1-to-clear (W1C) bits. The MMU interrupt handling code clears any
exceptions, but does so by masking out any other bits and writing the
result back. There are some important control bits in that register,
including MMU_ENABLE, so a safer approach is to simply write back the
value just read unaltered.

Signed-off-by: Phil Elwell <phil at raspberrypi.org>
---
 drivers/gpu/drm/v3d/v3d_irq.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/v3d/v3d_irq.c b/drivers/gpu/drm/v3d/v3d_irq.c
index 0be2eb7..e714d53 100644
--- a/drivers/gpu/drm/v3d/v3d_irq.c
+++ b/drivers/gpu/drm/v3d/v3d_irq.c
@@ -178,10 +178,7 @@ v3d_hub_irq(int irq, void *arg)
 		};
 		const char *client = "?";
 
-		V3D_WRITE(V3D_MMU_CTL,
-			  V3D_READ(V3D_MMU_CTL) & (V3D_MMU_CTL_CAP_EXCEEDED |
-						   V3D_MMU_CTL_PT_INVALID |
-						   V3D_MMU_CTL_WRITE_VIOLATION));
+		V3D_WRITE(V3D_MMU_CTL, V3D_READ(V3D_MMU_CTL));
 
 		if (v3d->ver >= 41) {
 			axi_id = axi_id >> 5;
-- 
2.7.4