Re: [PATCH 10/22] drm/i915: Support for extra alignment for tiled surfaces

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

On Wed, Oct 21, 2015 at 01:22:43PM +0200, Daniel Vetter wrote:
> On Wed, Oct 14, 2015 at 07:29:02PM +0300, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > SKL+ needs >4K alignment for tiled surfaces, so make
> > intel_compute_page_offset() handle it.
> > 
> > The way we do it is first we compute the closest tile boundary
> > as before, and then figure out how many tiles we need to go
> > to reach the desired alignment. The difference in the offset
> > is then added into the x/y offsets.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 51 ++++++++++++++++++++++++++++++++----
> >  1 file changed, 46 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 5f3abce..85e1473 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -2479,6 +2479,39 @@ static void intel_rotate_tile_dims(unsigned int *tile_width,
> >  }
> >  
> >  /*
> > + * Adjust the page offset by moving the difference into
> > + * the x/y offsets.
> > + *
> > + * Input tile dimensions and pitch must already be
> > + * rotated to match x and y, and in pixel units.
> > + * intel_rotate_tile_dims() gives exactly that.
> > + */
> > +static void intel_adjust_page_offset(int *x, int *y,
> > +				     unsigned int tile_width,
> > +				     unsigned int tile_height,
> > +				     unsigned int tile_size,
> > +				     unsigned int pitch,
> > +				     unsigned int old_offset,
> > +				     unsigned int new_offset)
> > +{
> > +	unsigned int tiles;
> > +
> > +	WARN_ON(old_offset & (tile_size - 1));
> > +	WARN_ON(new_offset & (tile_size - 1));
> > +	WARN_ON(new_offset > old_offset);
> > +
> > +	tiles = (old_offset - new_offset) / tile_size;
> > +	if (tiles == 0)
> > +		return;
> > +
> > +	/* pitch in tiles */
> > +	pitch /= tile_width;
> 
> Isn't tile_width here now in pixels and no longer in bytes? And we need
> bytes here I think, i.e. tile_pitch.

Everything is in pixels here, apart from the offsets.

> 
> > +
> > +	*y += tiles / pitch * tile_height;
> > +	*x += tiles % pitch * tile_width;
> 
> But here we need tile_width in pixels. I'm confused.
> 
> > +}
> > +
> > +/*
> >   * Computes the linear offset to the base tile and adjusts
> >   * x, y. bytes per pixel is assumed to be a power-of-two.
> >   *
> > @@ -2493,6 +2526,12 @@ unsigned long intel_compute_page_offset(struct drm_i915_private *dev_priv,
> >  					unsigned int pitch,
> >  					unsigned int rotation)
> >  {
> > +	unsigned int offset, alignment;
> > +
> > +	alignment = intel_surf_alignment(dev_priv, fb_modifier);
> > +	if (alignment)
> > +		alignment--;
> > +
> >  	if (fb_modifier != DRM_FORMAT_MOD_NONE) {
> >  		unsigned int tile_size, tile_width, tile_height;
> >  		unsigned int tile_rows, tiles;
> > @@ -2510,16 +2549,18 @@ unsigned long intel_compute_page_offset(struct drm_i915_private *dev_priv,
> >  		tiles = *x / tile_width;
> >  		*x %= tile_width;
> >  
> > -		return (tile_rows * (pitch / tile_width) + tiles) * tile_size;
> > -	} else {
> > -		unsigned int alignment = intel_linear_alignment(dev_priv) - 1;
> > -		unsigned int offset;
> > +		offset = (tile_rows * (pitch / tile_width) + tiles) * tile_size;
> >  
> > +		intel_adjust_page_offset(x, y, tile_width, tile_height,
> > +					 tile_size, pitch,
> > +					 offset, offset & ~alignment);
> 
> offset_aligned = ALIGN(offset, alignment); instead of open-coding it.

ALIGN() does the wrong thing.

> -Daniel
> 
> > +	} else {
> >  		offset = *y * pitch + *x * cpp;
> >  		*y = (offset & alignment) / pitch;
> >  		*x = ((offset & alignment) - *y * pitch) / cpp;
> > -		return offset & ~alignment;
> >  	}
> > +
> > +	return offset & ~alignment;
> >  }
> >  
> >  static int i9xx_format_to_fourcc(int format)
> > -- 
> > 2.4.9
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://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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