[igt-dev] [PATCH i-g-t 5/6] lib/i915: Add ADL-P stride restrictions for non-linear buffers

[Imre Deak]

On Fri, Jun 04, 2021 at 11:51:51PM +0300, Souza, Jose wrote:
> Hum we can drop this change, Imre landed changes to make framebuffers
> strides power of two for adl_p, so for userspace it should be
> transparent.

Yes, it should be transparent for CCS framebuffers too, however that's a
TODO item. I suspect that kernel would need to recreate the CCS plane if
the main surface stride changes (since the layout of each CCS page would
change, so we can't just remap the CCS pages), hence left this part for
a follow-up.

So this patch is needed.

> On Fri, 2021-06-04 at 13:39 -0700, Matt Roper wrote:
> > From: José Roberto de Souza <jose.souza at intel.com>
> > 
> > ADL-P tiled framebuffer strides must be power-of-two aligned and has a
> > minimum of 8 tiles. For non-CCS framebuffers the driver supports FBs not
> > meeting this requirement by remapping the framebuffer and padding the
> > stride as required, but for CCS FBs userspace must ensure the alignment.
> > Adding remap support for CCS FBs to the driver is to be done as a
> > follow-up.
> > 
> > Cc: Juha-Pekka Heikkilä <juha-pekka.heikkila at intel.com>
> > Cc: Anusha Srivatsa <anusha.srivatsa at intel.com>
> > Cc: Clinton Taylor <Clinton.A.Taylor at intel.com>
> > Cc: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
> > Cc: Imre Deak <imre.deak at intel.com>
> > Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> > Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
> > ---
> >  lib/igt_fb.c | 26 +++++++++++++++++++++-----
> >  1 file changed, 21 insertions(+), 5 deletions(-)
> > 
> > diff --git a/lib/igt_fb.c b/lib/igt_fb.c
> > index 585ede38..ce2aa6ce 100644
> > --- a/lib/igt_fb.c
> > +++ b/lib/igt_fb.c
> > @@ -729,8 +729,16 @@ static uint32_t calc_plane_stride(struct igt_fb *fb, int plane)
> >  		/* clear color always fixed to 64 bytes */
> >  		return 64;
> >  	} else if (is_gen12_ccs_plane(fb, plane)) {
> > -		/* A main surface using a CCS AUX surface must be 4x4 tiles aligned. */
> > -		return ALIGN(min_stride, 64);
> > +		/*
> > +		 * A main surface using a CCS AUX surface must be 4x4 tiles
> > +		 * aligned.  On ADL_P the minimum main surface stride is 8
> > +		 * tiles (2 * 64 byte on CCS surface) and it has to be POT
> > +		 * aligned.
> > +		 */
> > +		if (IS_ALDERLAKE_P(intel_get_drm_devid(fb->fd)))
> > +			return roundup_power_of_two(max(min_stride, 128u));
> > +		else
> > +			return ALIGN(min_stride, 64);
> >  	} else if (!fb->modifier && is_nouveau_device(fb->fd)) {
> >  		int align;
> >  
> > @@ -743,14 +751,22 @@ static uint32_t calc_plane_stride(struct igt_fb *fb, int plane)
> >  		return ALIGN(min_stride, align);
> >  	} else {
> >  		unsigned int tile_width, tile_height;
> > +		uint32_t stride;
> >  
> >  		igt_get_fb_tile_size(fb->fd, fb->modifier, fb->plane_bpp[plane],
> >  				     &tile_width, &tile_height);
> >  
> > -		if (is_gen12_ccs_modifier(fb->modifier))
> > -			tile_width *= 4;
> > +		if (is_gen12_ccs_modifier(fb->modifier)) {
> > +			stride = ALIGN(min_stride, tile_width * 4);
> >  
> > -		return ALIGN(min_stride, tile_width);
> > +			/* TODO: add support to kernel to POT align CCS format strides */
> > +			if (IS_ALDERLAKE_P(intel_get_drm_devid(fb->fd)))
> > +				stride = roundup_power_of_two(max(stride, tile_width * 8));
> > +		} else {
> > +			stride = ALIGN(min_stride, tile_width);
> > +		}
> > +
> > +		return stride;
> >  	}
> >  }
> >  
>