[AMD Official Use Only - General]
If the condition was met and it came to execute vcn_4_0_stop_dpg_mode, then it
would never have a chance to go for /*wait for vcn idle*/, isn't it?
I still didn't see obvious purpose of this change.
if (adev->pg_flags & AMD_PG_SUPPORT_VCN_DPG) {
==> r = vcn_v4_0_stop_dpg_mode(adev, i);
continue;
}
/* wait for vcn idle */
r = SOC15_WAIT_ON_RREG(VCN, i, regUVD_STATUS,
UVD_STATUS__IDLE, 0x7);
Thanks
Ruijing
-----Original Message-----
From: Khalid Masum <[email protected]>
Sent: Monday, August 15, 2022 11:11 AM
To: Dong, Ruijing <[email protected]>; [email protected];
[email protected]; [email protected];
[email protected]
Cc: Deucher, Alexander <[email protected]>; Koenig, Christian
<[email protected]>; Pan, Xinhui <[email protected]>; David Airlie
<[email protected]>; Daniel Vetter <[email protected]>; Zhu, James
<[email protected]>; Jiang, Sonny <[email protected]>; Wan Jiabing
<[email protected]>; Liu, Leo <[email protected]>
Subject: Re: [PATCH linux-next] drm/amdgpu/vcn: Remove unused assignment in
vcn_v4_0_stop
On 8/15/22 20:15, Dong, Ruijing wrote:
> [AMD Official Use Only - General]
>
> Sorry, which "r" value was overwritten? I didn't see the point of making
> this change.
>
> Thanks
> Ruijing
>
> -----Original Message-----
> From: Khalid Masum <[email protected]>
> Sent: Monday, August 15, 2022 3:01 AM
> To: [email protected]; [email protected];
> [email protected];
> [email protected]
> Cc: Deucher, Alexander <[email protected]>; Koenig, Christian
> <[email protected]>; Pan, Xinhui <[email protected]>; David
> Airlie <[email protected]>; Daniel Vetter <[email protected]>; Zhu, James
> <[email protected]>; Jiang, Sonny <[email protected]>; Dong, Ruijing
> <[email protected]>; Wan Jiabing <[email protected]>; Liu, Leo
> <[email protected]>; Khalid Masum <[email protected]>
> Subject: [PATCH linux-next] drm/amdgpu/vcn: Remove unused assignment
> in vcn_v4_0_stop
>
> The value assigned from vcn_v4_0_stop_dbg_mode to r is overwritten before it
> can be used. Remove this assignment.
>
> Addresses-Coverity: 1504988 ("Unused value")
> Fixes: 8da1170a16e4 ("drm/amdgpu: add VCN4 ip block support")
> Signed-off-by: Khalid Masum <[email protected]>
> ---
> drivers/gpu/drm/amd/amdgpu/vcn_v4_0.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/vcn_v4_0.c
> b/drivers/gpu/drm/amd/amdgpu/vcn_v4_0.c
> index ca14c3ef742e..80b8a2c66b36 100644
> --- a/drivers/gpu/drm/amd/amdgpu/vcn_v4_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/vcn_v4_0.c
> @@ -1154,7 +1154,7 @@ static int vcn_v4_0_stop(struct amdgpu_device *adev)
> fw_shared->sq.queue_mode |= FW_QUEUE_DPG_HOLD_OFF;
>
> if (adev->pg_flags & AMD_PG_SUPPORT_VCN_DPG) {
> - r = vcn_v4_0_stop_dpg_mode(adev, i);
> + vcn_v4_0_stop_dpg_mode(adev, i);
> continue;
> }
>
> --
> 2.37.1
>
After value is overwritten soon right after the diff.
See:
drivers/gpu/drm/amd/amdgpu/vcn_v4_0.c
static int vcn_v4_0_stop(struct amdgpu_device *adev) {
volatile struct amdgpu_vcn4_fw_shared *fw_shared; ...
for (i = 0; i < adev->vcn.num_vcn_inst; ++i) {
fw_shared = adev->vcn.inst[i].fw_shared.cpu_addr;
fw_shared->sq.queue_mode |= FW_QUEUE_DPG_HOLD_OFF;
if (adev->pg_flags & AMD_PG_SUPPORT_VCN_DPG) {
r = vcn_v4_0_stop_dpg_mode(adev, i);
continue;
}
/* wait for vcn idle */
r = SOC15_WAIT_ON_RREG(VCN, i, regUVD_STATUS,
UVD_STATUS__IDLE, 0x7);
Here, any value assigned to r is overwritten before it could be used. So the
assignment in the true branch of the if statement here can be removed.
Thanks,
-- Khalid Masum
