[PATCH V6 0/6] iommu/msm: Add DT adaptation and generic bindings support

[Rob Clark]

On Fri, Aug 12, 2016 at 3:00 AM, Sricharan <sricharan at codeaurora.org> wrote:
> Hi Rob,
>
>>> btw, the current state, at least on linaro integration branch, fault
>>> handling doesn't work so well (ie. device never gets resumed).. which
>>> is a bit unfortunate for a gpu (and results in a *lot* of rebooting on
>>> my part when debugging userspace).  I haven't had time yet to compare
>>> to the ancient downstream driver, but not sure if you have any ideas?
>>>
>>> I guess probably disabling stall on fault would help.  But I'm not
>>> even getting the "Fault occurred in context.." prints.  Seeing the
>>> fault iova is pretty useful since that plus gpu cmdstream trace helps
>>> me figure out which texture/etc is being accessed out of bounds.
>>
>>fyi, it looks like it is not getting any fault irq..  it's *possible*
>>that I screwed up the irq #'s when translating from downstream, so you
>>might want to double check that.  I thought I had it right, I assume I
>>would have noticed during piglit runs if fault recovery wasn't working
>>(since the result is that *everything* after the faulting test would
>>have failed since gpu is wedged with no access to memory), but it was
>>long enough ago that I can't claim that definitively.
>>
>>If you need an easy way to trigger a gpu fault, msmtest is a good way,
>>change this line:
>>
>>  https://github.com/freedreno/msmtest/blob/master/msmtest.c#L247
>>
>>from OUT_RELOC() to OUT_RING(ring, 0x00000000) will trigger a fault.
>>
>    So for the irq to be triggered, 'non-secure' irq line has to be
>   populated in DT. There is a 'secure'and 'non-secure' irq lines for these iommus
>   and  non-secure irq number is secure + 1. I tested this by having a 'return 0'
>  from the msm_iommu_map (no mapping), and the faults were getting triggered.
>
>   Can you share me your dts data ?
>

I think this is what you want:

https://github.com/freedreno/kernel-msm/blob/integration-linux-qcomlt/arch/arm/boot/dts/qcom-apq8064.dtsi#L2008

I haven't tested a display fault, so I suppose it is possible that
irq's are working for some iommu instances but not others?

BR,
-R

>
> Regards,
>  Sricharan
>