On Fri, Apr 21, 2023 at 10:27:22AM -0700, Yang, Fei wrote:
> > On Wed, Apr 19, 2023 at 04:00:53PM -0700, fei.yang@xxxxxxxxx wrote:
> >> From: Fei Yang <fei.yang@xxxxxxxxx>
> >>
> >> PTE encode functions are platform dependent. This patch implements
> >> PTE functions for MTL, and ensures the correct PTE encode function
> >> is used by calling pte_encode function pointer instead of the
> >> hardcoded gen8 version of PTE encode.
> >>
> >> Signed-off-by: Fei Yang <fei.yang@xxxxxxxxx>
> >> Reviewed-by: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
> >> Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
> >> Acked-by: Nirmoy Das <nirmoy.das@xxxxxxxxx>
> >
> > Bspec: 45015, 45040
> >
> >> ---
> >> drivers/gpu/drm/i915/display/intel_dpt.c | 2 +-
> >> drivers/gpu/drm/i915/gt/gen8_ppgtt.c | 45 ++++++++++++++++++++----
> >> drivers/gpu/drm/i915/gt/intel_ggtt.c | 36 +++++++++++++++++--
> >> 3 files changed, 72 insertions(+), 11 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/display/intel_dpt.c
> b/drivers/gpu/drm/i915/display/intel_dpt.c
> >> index b8027392144d..c5eacfdba1a5 100644
> >> --- a/drivers/gpu/drm/i915/display/intel_dpt.c
> >> +++ b/drivers/gpu/drm/i915/display/intel_dpt.c
> >> @@ -300,7 +300,7 @@ intel_dpt_create(struct intel_framebuffer *fb)
> >> vm->vma_ops.bind_vma = dpt_bind_vma;
> >> vm->vma_ops.unbind_vma = dpt_unbind_vma;
> >>
> >> - vm->pte_encode = gen8_ggtt_pte_encode;
> >> + vm->pte_encode = vm->gt->ggtt->vm.pte_encode;
> >>
> >> dpt->obj = dpt_obj;
> >> dpt->obj->is_dpt = true;
> >> diff --git a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
> b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
> >> index 4daaa6f55668..11b91e0453c8 100644
> >> --- a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
> >> +++ b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
> >> @@ -55,6 +55,34 @@ static u64 gen8_pte_encode(dma_addr_t addr,
> >> return pte;
> >> }
> >>
> >> +static u64 mtl_pte_encode(dma_addr_t addr,
> >> + enum i915_cache_level level,
> >> + u32 flags)
> >> +{
> >> + gen8_pte_t pte = addr | GEN8_PAGE_PRESENT | GEN8_PAGE_RW;
> >> +
> >> + if (unlikely(flags & PTE_READ_ONLY))
> >> + pte &= ~GEN8_PAGE_RW;
> >> +
> >> + if (flags & PTE_LM)
> >> + pte |= GEN12_PPGTT_PTE_LM | GEN12_PPGTT_PTE_NC;
> >
> > GEN12_PPGTT_PTE_NC got defined in the previous patch as BIT(5). But
> > according to bspec 45040, bit 5 is ignored in the PTE encoding. What is
> > this trying to do?
> This takes effect only for PTE_LM, doesn't affect MTL.
> PTE_NC is needed for PVC (use of access counter).
> I believe this function was writen based on the one for PVC. And this
> function
> did get extended to cover all gen12 in a later patch.
Even though MTL doesn't have local memory, PTE_LM is supposed to be used
on MTL for access to BAR2 stolen memory.
Matt
> -Fei
> > Matt
> >
> >> +
> >> + switch (level) {
> >> + case I915_CACHE_NONE:
> >> + pte |= GEN12_PPGTT_PTE_PAT1;
> >> + break;
--
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation
