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

[Neil Armstrong]

Hi Robyn,

On 31/05/2019 15:47, Robin Murphy wrote:
> On 31/05/2019 13:04, Tomeu Vizoso wrote:
>> 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]
>>>>> [Â 345.204813] panfrost 1800000.gpu: mmu irq status=1
>>>>> [Â 345.209617] panfrost 1800000.gpu: Unhandled Page fault in AS0 at VA
>>>>> 0x0000000002400400
>>>>
>>>> Â 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.
>>
>> Is this complication something you can explain? I don't know what v4
>> and v5 are meant here.
> 
> I was alluding to BASE_HW_FEATURE_V4, which I believe refers to the Midgard architecture version - the older versions implemented by T6xx and T720 seem to be collectively treated as "v4", while T760 and T8xx would effectively be "v5".
> 
>>> [ 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? ]
>>
>> I'm looking right now at getting Panfrost working on T720 with 64-bit
>> descriptors, with the ultimate goal of making Panfrost
>> 64-bit-descriptor only so we can have a single build of Mesa in
>> distros.
> 
> Cool, I'll keep an eye out, and hope that it might be enough for T620 on Juno, too :)
> 
>>> 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.
>>
>> Mmaps seem to work with this patch, thanks.
>>
>> The main complication I'm facing right now seems to be that the SFBD
>> descriptor on T720 seems to be different from the one we already had
>> (tested on T6xx?).
> 
> OK - with the 32-bit hack pointed to up-thread, a quick kmscube test gave me the impression that T720 works fine, but on closer inspection some parts of glmark2 do seem to go a bit wonky (although I suspect at least some of it is just down to the FPGA setup being both very slow and lacking in memory bandwidth), and the "nv12-1img" mode of kmscube turns out to render in some delightfully wrong colours.
> 
> I'll try to get a 'proper' version of the io-pgtable patch posted soon.

I'm trying to collect all the fixes needed to make T820 work again, and
I was wondering if you finally have a proper patch for this and "cfg->ias > 48"
hack ? Or one I can test ?

Thanks,
Neil

> 
> Thanks,
> Robin.
> 
>>
>> Cheers,
>>
>> Tomeu
>>
>>> 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)
>>> ÂÂÂÂÂÂÂÂ iop = arm_64_lpae_alloc_pgtable_s1(cfg, cookie);
>>> ÂÂÂÂÂÂÂÂ if (iop) {
>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ u64 mair, ttbr;
>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(&iop->ops);
>>>
>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ data->levels = 4;
>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ /* Copy values as union fields overlap */
>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ mair = cfg->arm_lpae_s1_cfg.mair[0];
>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ttbr = cfg->arm_lpae_s1_cfg.ttbr[0];
>>>
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