[Intel-gfx] [PATCH 3/8] drm/i915/mtl: Add PTE encode function

[Yang, Fei]

> On Wed, Apr 19, 2023 at 04:00:53PM -0700, fei.yang at intel.com wrote:
>> From: Fei Yang <fei.yang at intel.com>
>>
>> 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 at intel.com>
>> Reviewed-by: Andrzej Hajda <andrzej.hajda at intel.com>
>> Reviewed-by: Andi Shyti <andi.shyti at linux.intel.com>
>> Acked-by: Nirmoy Das <nirmoy.das at intel.com>
>
> 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.

-Fei

> Matt
>
>> +
>> +     switch (level) {
>> +     case I915_CACHE_NONE:
>> +             pte |= GEN12_PPGTT_PTE_PAT1;
>> +             break;

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