[PATCH] drm/amd/amdgpu: Correct ring wptr address in debugfs

[Christian König]

Am 29.03.2017 um 19:44 schrieb Tom St Denis:
> On 29/03/17 01:41 PM, Christian König wrote:
>> Am 29.03.2017 um 19:07 schrieb Tom St Denis:
>>> On 29/03/17 01:07 PM, Tom St Denis wrote:
>>>> On gfx9 hardware the value is not wrapped and is a 64-bit value.  So
>>>> we reduce it modulo the ring size.
>>>>
>>>> Signed-off-by: Tom St Denis <tom.stdenis at amd.com>
>>>> ---
>>>>  drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c | 4 ++--
>>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
>>>> index ac0ce3f27f87..b6d2c0b2a501 100644
>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
>>>> @@ -320,8 +320,8 @@ static ssize_t amdgpu_debugfs_ring_read(struct
>>>> file *f, char __user *buf,
>>>>
>>>>      if (*pos < 12) {
>>>>          early[0] = amdgpu_ring_get_rptr(ring);
>>>> -        early[1] = amdgpu_ring_get_wptr(ring);
>>>> -        early[2] = ring->wptr;
>>>> +        early[1] = amdgpu_ring_get_wptr(ring) & ((ring->ring_size >>
>>>> 2) - 1);
>>>> +        early[2] = ring->wptr & ((ring->ring_size >> 2) - 1);
>>>>          for (i = *pos / 4; i < 3 && size; i++) {
>>>>              r = put_user(early[i], (uint32_t *)buf);
>>>>              if (r)
>>>>
>>>
>>> Particularly if reviewers could make sure I got the dword/byte
>>> conversion correct here.  It's my understanding ring_size is bytes and
>>> the get_*ptr() macros is in dwords right?
>>
>> Actually you should use ptr_mask here instead, this way you don't need
>> to mess with the ring size at all.
>
>     ring->buf_mask = (ring->ring_size / 4) - 1;
>     ring->ptr_mask = ring->funcs->support_64bit_ptrs ?
>         0xffffffffffffffff : ring->buf_mask;
>
> This won't wrap the value like debugfs needs though.

Ups, I meant buf_mask instead of ptr_mask.

We seem to mess those two up more than once, might think about a better 
name for them.

Christian.

>
> Tom