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Subject: Re: [PATCH v6 0/6] Allwinner H6 Mali GPU support
To:     Neil Armstrong <narmstrong@baylibre.com>,
        Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc:     =?UTF-8?B?Q2zDqW1lbnQgUMOpcm9u?= <peron.clem@gmail.com>,
        Mark Rutland <mark.rutland@arm.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>, David Airlie <airlied@linux.ie>,
        Will Deacon <will.deacon@arm.com>,
        open list <linux-kernel@vger.kernel.org>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        Steven Price <steven.price@arm.com>,
        Maxime Ripard <maxime.ripard@bootlin.com>,
        Chen-Yu Tsai <wens@csie.org>, Rob Herring <robh+dt@kernel.org>,
        Linux IOMMU <iommu@lists.linux-foundation.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>
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From:   Robin Murphy <robin.murphy@arm.com>
Message-ID: <8433455c-3b74-c176-49a1-388b3f085e9e@arm.com>
Date:   Wed, 28 Aug 2019 12:49:07 +0100
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Hi Neil,

On 28/08/2019 12:28, Neil Armstrong wrote:
> Hi Robin,
> 
> 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@arm.com> wrote:
>>>>
>>>> On 29/05/2019 16:09, Tomeu Vizoso wrote:
>>>>> On Tue, 21 May 2019 at 18:11, Clément Péron <peron.clem@gmail.com> 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.
>>>
>>> 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 Clément 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 ?

I do have a handful of io-pgtable patches written up and ready to go, 
I'm just treading carefully and waiting for the internal approval box to 
be ticked before I share anything :(

Robin.

> 
> 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)
>>>>           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];
>>>>
>>>> _______________________________________________
>>>> dri-devel mailing list
>>>> dri-devel@lists.freedesktop.org
>>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>