Re: [PATCH v4 3/3] drm/radeon: fix scatter-gather mapping with user pages

[Alex Deucher]

On Wed, Mar 25, 2020 at 11:54 AM Shane Francis <bigbeeshane@xxxxxxxxx> wrote:
>
> > >-----Original Message-----
> > >From: dri-devel <dri-devel-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of
> > >Shane Francis
> > >Sent: Wednesday, March 25, 2020 5:08 AM
> > >To: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > >Cc: airlied@xxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; bigbeeshane@xxxxxxxxx;
> > >amd-gfx-request@xxxxxxxxxxxxxxxxxxxxx; alexander.deucher@xxxxxxx;
> > >christian.koenig@xxxxxxx
> > >Subject: [PATCH v4 3/3] drm/radeon: fix scatter-gather mapping with user
> > >pages
> > >
> > >Calls to dma_map_sg may return segments / entries than requested
> >
> > "may return less segment..." ?
> >                        ^^^
>
> I will reword / fix the highlighted issues with the text and send a updated
> patch set later today.

I'll fix it up locally when I apply it.  Thanks!

Alex

>
> >
> > >if they fall on page bounderies. The old implementation did not
> > >support this use case.
> > >
> > >Signed-off-by: Shane Francis <bigbeeshane@xxxxxxxxx>
> > >---
> > > drivers/gpu/drm/radeon/radeon_ttm.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > >diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c
> > >b/drivers/gpu/drm/radeon/radeon_ttm.c
> > >index 3b92311d30b9..b3380ffab4c2 100644
> > >--- a/drivers/gpu/drm/radeon/radeon_ttm.c
> > >+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
> > >@@ -528,7 +528,7 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt
> > >*ttm)
> > >
> > >       r = -ENOMEM;
> > >       nents = dma_map_sg(rdev->dev, ttm->sg->sgl, ttm->sg->nents,
> > >direction);
> > >-      if (nents != ttm->sg->nents)
> > >+      if (nents == 0)
> > >               goto release_sg;
> >
> > This looks correct to me.
> >
> > Reviewed-by: Michael J. Ruhl <michael.j.ruhl@xxxxxxxxx>
> >
> > M
> > >       drm_prime_sg_to_page_addr_arrays(ttm->sg, ttm->pages,
> > >--
> > >2.26.0
> > >
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