[PATCH] drm/amd/amdgpu: Fix wave mask in amdgpu_debugfs_wave_read()

[Christian König]

Am 10.11.2017 um 19:03 schrieb Tom St Denis:
> The bottom two bits of the simd value were being put into
> the upper bits of the wave value which was likely working due
> to the bits being ignored (or aliased).
>
> Eitherway, now we mask it correctly.
>
> Signed-off-by: Tom St Denis <tom.stdenis at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index c1f1b8f15395..cc59020d5874 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -3766,7 +3766,7 @@ static ssize_t amdgpu_debugfs_wave_read(struct file *f, char __user *buf,
>   	se = ((*pos >> 7) & 0xFF);
>   	sh = ((*pos >> 15) & 0xFF);
>   	cu = ((*pos >> 23) & 0xFF);
> -	wave = ((*pos >> 31) & 0xFF);
> +	wave = ((*pos >> 31) & 0x3F);
>   	simd = ((*pos >> 37) & 0xFF);

Have you considered using GENMASK_ULL instead of fiddling with the hex 
masks manually?

E.g. that would look like this

se = (*pos & GENMASK_ULL(14, 7)) >> 7;
sh = (*pos & GENMASK_ULL(22, 15)) >> 15;
cu = (*pos & GENMASK_ULL(30, 23)) >> 23;
wave = (*pos & GENMASK_ULL(36, 31)) >> 31;
simd = (*pos & GENMASK_ULL(44, 37)) >> 37;

if you ask me makes it totally obvious what is happening here and avoids 
such typos.

Might be that we even have some GENMASK_ULL + shift macro somewhere in 
the kernel, but I don't know of anything of hand.

Christian.

>   
>   	/* switch to the specific se/sh/cu */