Re: [RFC PATCH 1/1] drm/amdgpu: fix usable gart size calculation

[Nirmoy <nirmodas@xxxxxxx>]

On 11/13/20 5:21 PM, Christian König wrote:
> Am 13.11.20 um 17:17 schrieb Nirmoy Das:
> > amdgpu_do_test_moves() is failing because of wrong
> > usable gart size calculation and throwing:
> >
> > [drm:amdgpu_do_test_moves [amdgpu]] *ERROR* 0000000020bdc9f3 bind failed
> >
> > Signed-off-by: Nirmoy Das <nirmoy.das@xxxxxxx>
> > ---
> >
> > This still doesn't work. As per my calculation 1st 4MB of GART is not
> > accounted for in adev->gmc.gart_size - 
> > atomic64_read(&adev->gart_pin_size).
>
> The member gart_pin_size should probably be renamed to gtt_pin_size, 
> but since a gtt pin is also automatically visible in the GART that 
> should probably be ok for now.
>
> > What am I missing ?
>
> The two 2MB windows in the GART which are used for buffer moves.
>
> See AMDGPU_GTT_MAX_TRANSFER_SIZE and AMDGPU_GTT_NUM_TRANSFER_WINDOWS.


Thanks, I should've asked much earlier :)


Nirmoy

> Regards,
> Christian.
>
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_test.c | 11 ++---------
> >   1 file changed, 2 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_test.c 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_test.c
> > index 6042b3b81a4c..d983c729997f 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_test.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_test.c
> > @@ -42,16 +42,9 @@ static void amdgpu_do_test_moves(struct 
> > amdgpu_device *adev)
> >       size = 1024 * 1024;
> >
> >       /* Number of tests =
> > -     * (Total GTT - IB pool - writeback page - ring buffers) / test 
> > size
> > +     * (Total GTT - gart_pin_size) / test size
> >        */
> > -    n = adev->gmc.gart_size - AMDGPU_IB_POOL_SIZE;
> > -    for (i = 0; i < AMDGPU_MAX_RINGS; ++i)
> > -        if (adev->rings[i])
> > -            n -= adev->rings[i]->ring_size;
> > -    if (adev->wb.wb_obj)
> > -        n -= AMDGPU_GPU_PAGE_SIZE;
> > -    if (adev->irq.ih.ring_obj)
> > -        n -= adev->irq.ih.ring_size;
> > +    n = adev->gmc.gart_size - atomic64_read(&adev->gart_pin_size);
> >       n /= size;
> >
> >       gtt_obj = kcalloc(n, sizeof(*gtt_obj), GFP_KERNEL);
> > --
> > 2.29.0
> >
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