On Wed, Aug 10, 2016 at 11:48:56AM +0200, Daniel Vetter wrote:
> On Wed, Aug 10, 2016 at 12:23:17PM +0300, ville.syrjala@xxxxxxxxxxxxxxx wrote:
> > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> >
> > Minimize the resulting X coordinate after intel_adjust_tile_offset() is
> > done with it's offset adjustment. This allows calling
> > intel_adjust_tile_offset() multiple times in case we need to adjust
> > the offset several times.
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> Do we check anywhere that y doesn't eventually overflow? Anyway, this
> looks good.
Hmm. I was thinking it's limited by the fb size, but only the plane src
coordinate part is limited like that. The part coming from fb->offsets[]
is extra, so I guess the total might end up too big even for 32 bits.
And the hardware for sure has even lower number of bits available for
the x/y offsets, so we should definitely add some extra checks for
this.
I have a feeling I had some checks like this at some point, but either I
imagined it, or I mistakenly threw them out, or they're in some random
branch I've misplaced.
>
> Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
>
> > ---
> > drivers/gpu/drm/i915/intel_display.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index f4b45625703e..40c809593ae9 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -2330,6 +2330,7 @@ static u32 intel_adjust_tile_offset(int *x, int *y,
> > u32 old_offset,
> > u32 new_offset)
> > {
> > + unsigned int pitch_pixels = pitch_tiles * tile_width;
> > unsigned int tiles;
> >
> > WARN_ON(old_offset & (tile_size - 1));
> > @@ -2341,6 +2342,10 @@ static u32 intel_adjust_tile_offset(int *x, int *y,
> > *y += tiles / pitch_tiles * tile_height;
> > *x += tiles % pitch_tiles * tile_width;
> >
> > + /* minimize x in case it got needlessly big */
> > + *y += *x / pitch_pixels * tile_height;
> > + *x %= pitch_pixels;
> > +
> > return new_offset;
> > }
> >
> > --
> > 2.7.4
> >
> > _______________________________________________
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> > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
--
Ville Syrjälä
Intel OTC
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