Check BSpec>Memory Views>Memory Types and Cache Interface>Memory Type [SKL+]>PAT (IA32e) [SKL+] -----Original Message----- From: Chris Wilson [mailto:chris@xxxxxxxxxxxxxxxxxx] Sent: Friday, September 8, 2017 5:27 PM To: Wang, Zhi A <zhi.a.wang@xxxxxxxxx>; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; intel-gvt-dev@xxxxxxxxxxxxxxxxxxxxx Cc: joonas.lahtinen@xxxxxxxxxxxxxxx; zhenyuw@xxxxxxxxxxxxxxx; Wang, Zhi A <zhi.a.wang@xxxxxxxxx>; Widawsky, Benjamin <benjamin.widawsky@xxxxxxxxx>; Vivi, Rodrigo <rodrigo.vivi@xxxxxxxxx> Subject: Re: [PATCH v8 4/5] drm/i915: Do not allocate unused PPAT entries Quoting Zhi Wang (2017-09-08 10:05:52) > Only PPAT entries 0/2/3/4 are using. Remove extra PPAT entry > allocation during initialization. > > v8: > > - Move ppat_index() into i915_gem_gtt.c. (Chris) > - Change the name of ppat_bits_to_index to ppat_index. > > Cc: Ben Widawsky <benjamin.widawsky@xxxxxxxxx> > Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Suggested-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> > Signed-off-by: Zhi Wang <zhi.a.wang@xxxxxxxxx> > --- > drivers/gpu/drm/i915/i915_gem_gtt.c | 53 > +++++++++++++++++++------------------ > 1 file changed, 27 insertions(+), 26 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c > b/drivers/gpu/drm/i915/i915_gem_gtt.c > index d8d2b4a..82cb97b 100644 > --- a/drivers/gpu/drm/i915/i915_gem_gtt.c > +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c > @@ -2979,6 +2979,13 @@ static unsigned int chv_private_pat_match(u8 src, u8 dst) > INTEL_PPAT_PERFECT_MATCH : 0; } > > +/* PPAT index = 4 * PAT + 2 * PCD + PWT */ static inline unsigned int > +ppat_index(unsigned int bits) { > + return (4 * !!(bits & _PAGE_PAT) + 2 * !!(bits & _PAGE_PCD) > + + !!(bits & _PAGE_PWT)); I'm feeling very dumb, having quickly grepped the bspec for why those bits map to a particular PAT entry. Clue for enlightenment? -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
