RE: linux-4.7-rc3/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c:4836: wierd condition ?

[Deucher, Alexander]

> -----Original Message-----
> From: David Binderman [mailto:linuxdev.baldrick@xxxxxxxxx]
> Sent: Monday, June 13, 2016 4:16 AM
> To: Deucher, Alexander; Koenig, Christian; airlied@xxxxxxxx; dri-
> devel@xxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> dcb314@xxxxxxxxxxx
> Subject: linux-4.7-rc3/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c:4836:
> wierd condition ?
> 
> Hello there,
> 
> linux-4.7-rc3/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c:4836]: (style)
> Boolean result is used in bitwise operation. Clarify expression with
> parentheses.
> 
> Source code is
> 
>             if ((ring->me == me_id) & (ring->pipe == pipe_id))
> 
> Maybe better code
> 
>             if ((ring->me == me_id) && (ring->pipe == pipe_id))
> 

Good catch.  Fixed in the attached patch.

> Also in the same file:
> 
> [drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c:3866]: (style) Variable 'data'
> is assigned a value that is never used.

The readback of the register here is needed to wake up the block after disabling powergating.

> [drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c:4321]: (style) Variable
> 'mc_shared_chmap' is assigned a value that is never used.

I think this one can be dropped.

> [drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c:4657]: (style) Variable 'tmp'
> is assigned a value that is never used.
> 

This operation requires a posted write (i.e., a read back of the register to make sure the write has completed).

Thanks!

Alex

> Regards
> 
> David Binderman

Attachment: 0001-drm-amdgpu-gfx7-fix-broken-condition-check.patch
Description: 0001-drm-amdgpu-gfx7-fix-broken-condition-check.patch