bcm27xx: sync 5.4 patches with RPi Foundation

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/target/linux/bcm27xx/patches-5.4/950-0333-drm-v3d-Don-t-clear-MMU-control-bits-on-exception.patch b/target/linux/bcm27xx/patches-5.4/950-0333-drm-v3d-Don-t-clear-MMU-control-bits-on-exception.patch
new file mode 100644
index 0000000000..a4a9dc817b
--- /dev/null
+++ b/target/linux/bcm27xx/patches-5.4/950-0333-drm-v3d-Don-t-clear-MMU-control-bits-on-exception.patch
@@ -0,0 +1,34 @@
+From e2d8a52d3ade83f5c114b1edba601ebcf2c39517 Mon Sep 17 00:00:00 2001
+From: Phil Elwell <phil@raspberrypi.org>
+Date: Mon, 11 Nov 2019 14:01:41 +0000
+Subject: [PATCH] drm/v3d: Don't clear MMU control bits on exception
+
+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.
+
+This patch doesn't remove the cause of the apparent PTE errors, but it
+does reduce the impact to just an error in the kernel log.
+
+Signed-off-by: Phil Elwell <phil@raspberrypi.org>
+---
+ drivers/gpu/drm/v3d/v3d_irq.c | 5 +----
+ 1 file changed, 1 insertion(+), 4 deletions(-)
+
+--- 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;