Re: [PATCH v6 0/6] Allwinner H6 Mali GPU support

[Tomeu Vizoso]

On Wed, 29 May 2019 at 19:38, Robin Murphy <robin.murphy@xxxxxxx> wrote:
>
> On 29/05/2019 16:09, Tomeu Vizoso wrote:
> > On Tue, 21 May 2019 at 18:11, ClÃment PÃron <peron.clem@xxxxxxxxx> wrote:
> >>
> > [snip]
> >> [  345.204813] panfrost 1800000.gpu: mmu irq status=1
> >> [  345.209617] panfrost 1800000.gpu: Unhandled Page fault in AS0 at VA
> >> 0x0000000002400400
> >
> >  From what I can see here, 0x0000000002400400 points to the first byte
> > of the first submitted job descriptor.
> >
> > So mapping buffers for the GPU doesn't seem to be working at all on
> > 64-bit T-760.
> >
> > Steven, Robin, do you have any idea of why this could be?
>
> I tried rolling back to the old panfrost/nondrm shim, and it works fine
> with kbase, and I also found that T-820 falls over in the exact same
> manner, so the fact that it seemed to be common to the smaller 33-bit
> designs rather than anything to do with the other
> job_descriptor_size/v4/v5 complication turned out to be telling.
>
> [ as an aside, are 64-bit jobs actually known not to work on v4 GPUs, or
> is it just that nobody's yet observed a 64-bit blob driving one? ]

Do you know if 64-bit descriptors work on v4 GPUs with our kernel
driver but with the DDK?

Wonder if there something else to be fixed in the kernel for that scenario.

Thanks,

Tomeu

> Long story short, it appears that 'Mali LPAE' is also lacking the start
> level notion of VMSA, and expects a full 4-level table even for <40 bits
> when level 0 effectively redundant. Thus walking the 3-level table that
> io-pgtable comes back with ends up going wildly wrong. The hack below
> seems to do the job for me; if ClÃment can confirm (on T-720 you'll
> still need the userspace hack to force 32-bit jobs as well) then I think
> I'll cook up a proper refactoring of the allocator to put things right.
>
> Robin.
>
>
> ----->8-----
> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index 546968d8a349..f29da6e8dc08 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -1023,12 +1023,14 @@ arm_mali_lpae_alloc_pgtable(struct
> io_pgtable_cfg *cfg, void *cookie)
>         iop = arm_64_lpae_alloc_pgtable_s1(cfg, cookie);
>         if (iop) {
>                 u64 mair, ttbr;
> +               struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(&iop->ops);
>
> +               data->levels = 4;
>                 /* Copy values as union fields overlap */
>                 mair = cfg->arm_lpae_s1_cfg.mair[0];
>                 ttbr = cfg->arm_lpae_s1_cfg.ttbr[0];
>
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