From a115162198028940c4b19d76a6aa7e2164ec2b7f Mon Sep 17 00:00:00 2001
From: Alex Deucher <alexander.deucher@amd.com>
Date: Thu, 2 Jun 2022 12:06:12 -0400
Subject: drm/amdgpu/discovery: add comments about VCN instance handling
Git-commit: 031ac4e419dfd8f099a0adba31f7f735013eb628
Patch-mainline: v6.0-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225 jsc#PED-2849
Add comments to clarify code that is safe, but triggers and
smatch warning.
Link: https://lists.freedesktop.org/archives/amd-gfx/2022-June/079905.html
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
index 91f21b725a43..b0811287f017 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
@@ -1435,6 +1435,11 @@ static int amdgpu_discovery_get_vcn_info(struct amdgpu_device *adev)
return -EINVAL;
}
+ /* num_vcn_inst is currently limited to AMDGPU_MAX_VCN_INSTANCES
+ * which is smaller than VCN_INFO_TABLE_MAX_NUM_INSTANCES
+ * but that may change in the future with new GPUs so keep this
+ * check for defensive purposes.
+ */
if (adev->vcn.num_vcn_inst > VCN_INFO_TABLE_MAX_NUM_INSTANCES) {
dev_err(adev->dev, "invalid vcn instances\n");
return -EINVAL;
@@ -1450,6 +1455,9 @@ static int amdgpu_discovery_get_vcn_info(struct amdgpu_device *adev)
switch (le16_to_cpu(vcn_info->v1.header.version_major)) {
case 1:
+ /* num_vcn_inst is currently limited to AMDGPU_MAX_VCN_INSTANCES
+ * so this won't overflow.
+ */
for (v = 0; v < adev->vcn.num_vcn_inst; v++) {
adev->vcn.vcn_codec_disable_mask[v] =
le32_to_cpu(vcn_info->v1.instance_info[v].fuse_data.all_bits);
--
2.38.1