On Fri, Nov 06, 2015 at 07:29:18PM -0800, Kenneth Graunke wrote:
> On Friday, November 06, 2015 06:12:27 PM Ben Widawsky wrote:
> > The comment in the code details the restriction. Thanks to Ken for having a
> > very
> > helpful conversation with me, and spotting the blurb in the link I sent him
> > :P.
> >
> > There are still stability problems for me on GT4, but this definitely helps
> > with
> > some of the failures.
> >
> > Cc: Kenneth Graunke <kenn...@whitecape.org>
> > Cc: Jordan Justen <jordan.l.jus...@intel.com>
> > Cc: mesa-sta...@lists.freedesktop.org (if the original gt4 patch goes to
> > stable)
> > ---
> >
> > Sarah, you should check this on KBL.
> > Cc: Sarah Sharp <sarah.a.sh...@linux.intel.com>
> > ---
> > src/mesa/drivers/dri/i965/brw_device_info.c | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/src/mesa/drivers/dri/i965/brw_device_info.c
> > b/src/mesa/drivers/dri/i965/brw_device_info.c
> > index 2ebc084..6117fd3 100644
> > --- a/src/mesa/drivers/dri/i965/brw_device_info.c
> > +++ b/src/mesa/drivers/dri/i965/brw_device_info.c
> > @@ -337,6 +337,14 @@ static const struct brw_device_info
> > brw_device_info_skl_gt3 = {
> >
> > static const struct brw_device_info brw_device_info_skl_gt4 = {
> > GEN9_FEATURES, .gt = 4,
> > + /* From the docs:
> > + * URB is limited to 1008KB due to programming restrictions. This is
> > not a
> > + * restriction of the L3 implementation, but of the FF and other
> > clients.
> > + * Therefore, in a GT4 implementation it is possible for the
> > programmed
> > + * allocation of the L3 data array to provide 3*384KB=1152MB [sic]
> > for URB,
> > + * but only 1008KB of this will be used.
> > + */
>
> We should at least say which page/section this comes from (the section
> name exists in the Broadwell PRM, so it's not particularly secret).
>
> Please put the text in quotes too. My suggested formatting:
>
> /* From the "L3 Allocation and Programming" documentation:
> *
> * "URB is limited to 1008KB due to programming restrictions. This
> * is not a restriction of the L3 implementation, but of the FF and
> * other clients. Therefore, in a GT4 implementation it is
> * possible for the programmed allocation of the L3 data array to
> * provide 3*384KB=1152MB [sic] for URB, but only 1008KB of this
> * will be used."
> */
>
> Regardless,
> Reviewed-by: Kenneth Graunke <kenn...@whitecape.org>
>
Thanks! I had no idea it was in the BDW PRMs.
> > + .urb.size = 1008 / 3,
> > };
> >
> > static const struct brw_device_info brw_device_info_bxt = {
> >
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