1 files changed, 36 insertions, 0 deletions
diff --git a/meta-amd-bsp/recipes-kernel/linux/linux-yocto-4.19.8/4029-drm-amdgpu-work-around-llvm-bug-42576.patch b/meta-amd-bsp/recipes-kernel/linux/linux-yocto-4.19.8/4029-drm-amdgpu-work-around-llvm-bug-42576.patch
new file mode 100644
index 00000000..f4772ba3
--- /dev/null
+++ b/meta-amd-bsp/recipes-kernel/linux/linux-yocto-4.19.8/4029-drm-amdgpu-work-around-llvm-bug-42576.patch
@@ -0,0 +1,36 @@
+From 44d1b0c79da2839e225acd43f07e57a07e73f224 Mon Sep 17 00:00:00 2001
+From: Arnd Bergmann <arnd@arndb.de>
+Date: Wed, 2 Oct 2019 14:01:27 +0200
+Subject: [PATCH 4029/4256] drm/amdgpu: work around llvm bug #42576
+
+Code in the amdgpu driver triggers a bug when using clang to build
+an arm64 kernel:
+
+/tmp/sdma_v4_0-f95fd3.s: Assembler messages:
+/tmp/sdma_v4_0-f95fd3.s:44: Error: selected processor does not support `bfc w0,#1,#5'
+
+I expect this to be fixed in llvm soon, but we can also work around
+it by inserting a barrier() that prevents the optimization.
+
+Link: https://bugs.llvm.org/show_bug.cgi?id=42576
+Signed-off-by: Arnd Bergmann <arnd@arndb.de>
+Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
+---
+ drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c b/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
+index cf784a4caa24..26f13de35b2c 100644
+--- a/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
++++ b/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
+@@ -958,6 +958,7 @@ static uint32_t sdma_v4_0_rb_cntl(struct amdgpu_ring *ring, uint32_t rb_cntl)
+ 	/* Set ring buffer size in dwords */
+ 	uint32_t rb_bufsz = order_base_2(ring->ring_size / 4);
+ 
++	barrier(); /* work around https://bugs.llvm.org/show_bug.cgi?id=42576 */
+ 	rb_cntl = REG_SET_FIELD(rb_cntl, SDMA0_GFX_RB_CNTL, RB_SIZE, rb_bufsz);
+ #ifdef __BIG_ENDIAN
+ 	rb_cntl = REG_SET_FIELD(rb_cntl, SDMA0_GFX_RB_CNTL, RB_SWAP_ENABLE, 1);
+-- 
+2.17.1
+