[Skiboot] [PATCH v3 05/10] npu2: Use read-modify-write in npu2_assign_gmb()

[Reza Arbab]

We currently set each half of the GPU memory BAR by OR'ing our half
into what is already there. This allows a possible conflict if Hostboot
or other system boot software has already written to the BAR.

Set each half of the BAR value directly instead of using OR.

Signed-off-by: Reza Arbab <arbab at linux.vnet.ibm.com>
Cc: Alistair Popple <alistair at popple.id.au>
Cc: Andrew Donnellan <andrew.donnellan at au1.ibm.com>
Cc: Frederic Barrat <fbarrat at linux.vnet.ibm.com>
---
 hw/npu2.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/hw/npu2.c b/hw/npu2.c
index c7e636f..e495728 100644
--- a/hw/npu2.c
+++ b/hw/npu2.c
@@ -630,14 +630,16 @@ static int npu2_assign_gmb(struct npu2_dev *ndev)
 
 	mode += ndev->bdfn & 0x7;
 	val = SETFIELD(NPU2_MEM_BAR_MODE, val, mode);
-	if (NPU2DEV_BRICK(ndev))
-		val >>= 32;
+
 	reg = NPU2_REG_OFFSET(NPU2_STACK_STCK_0 + NPU2DEV_STACK(ndev),
 			      NPU2_BLOCK_SM_0,
 			      NPU2_GPU0_MEM_BAR);
 
 	old_val = npu2_read(p, reg);
-	val |= old_val;
+	if (NPU2DEV_BRICK(ndev))
+		val = SETFIELD(PPC_BITMASK(32, 63), old_val, val >> 32);
+	else
+		val = SETFIELD(PPC_BITMASK(0, 31), old_val, val >> 32);
 
 	npu2_write(p, reg, val);
 	reg = NPU2_REG_OFFSET(NPU2_STACK_STCK_0 + NPU2DEV_STACK(ndev),
-- 
1.8.3.1