Re: [igt-dev] [PATCH i-g-t v2 1/2] lib/intel_bufops: Introduce buffer operations

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Dec 03, 2019 at 06:05:58PM +0100, Zbigniew Kempczyński wrote:
> On Tue, Dec 03, 2019 at 10:25:29AM +0100, Katarzyna Dec wrote:
> 
> <cut>
> > > +static void *x_ptr(void *ptr,
> > > +		   unsigned int x, unsigned int y,
> > > +		   unsigned int stride, unsigned int cpp)
> > > +{
> > > +	const int tile_width = 512;
> > > +	const int tile_height = 8;
> > It can be really silly question - are these ^ values always the same?
> 
> Yes.

If you ignore gen2.

> 
> > > +	const int tile_size = tile_width * tile_height;
> > > +	int tile_x, tile_y;
> > > +	int offset_x, offset_y, pos;
> > > +
> > > +	x *= cpp;
> > > +	tile_x = x / tile_width;
> > > +	tile_y = y / tile_height;
> > > +	offset_x = (tile_x * tile_size);
> > > +	offset_y = (tile_y * stride * tile_height);
> > > +
> > > +	pos = offset_y + offset_x +
> > > +			(y % tile_height * tile_width) + (x % tile_width);
> > > +
> > > +	return ptr + pos;
> > > +}
> > > +
> > > +static void *y_ptr(void *ptr,
> > > +		   unsigned int x, unsigned int y,
> > > +		   unsigned int stride, unsigned int cpp)
> > > +{
> > > +	const int tile_width = 128;
> > > +	const int tile_height = 32;
> > > +	const int owords = 16;
> > Similar question. I guess this is something specific either to Intel Gen or to
> > testcases.
> 
> Tile-n where n is X/Y/Yf/Ys/... describe data placement algorithms
> to be CPU/GPU cache-friendly. 

These numbers also only work for i945+.

-- 
Ville Syrjälä
Intel
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