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Groups > linux.kernel > #1686474
| From | Rob Clark <robdclark@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device |
| Date | 2017-07-13 14:00 +0200 |
| Message-ID | <u2KWJ-58b-11@gated-at.bofh.it> (permalink) |
| References | (1 earlier) <u0bqp-2sh-13@gated-at.bofh.it> <u2yLU-5QV-17@gated-at.bofh.it> <u2EHD-1nz-1@gated-at.bofh.it> <u2G6K-2a4-19@gated-at.bofh.it> <u2J4C-3Zi-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Thu, Jul 13, 2017 at 5:50 AM, Robin Murphy <robin.murphy@arm.com> wrote:
> On 13/07/17 07:48, Stephen Boyd wrote:
>> On 07/13, Vivek Gautam wrote:
>>> Hi Stephen,
>>>
>>>
>>> On 07/13/2017 04:24 AM, Stephen Boyd wrote:
>>>> On 07/06, Vivek Gautam wrote:
>>>>> @@ -1231,12 +1237,18 @@ static int arm_smmu_map(struct iommu_domain *domain, unsigned long iova,
>>>>> static size_t arm_smmu_unmap(struct iommu_domain *domain, unsigned long iova,
>>>>> size_t size)
>>>>> {
>>>>> - struct io_pgtable_ops *ops = to_smmu_domain(domain)->pgtbl_ops;
>>>>> + struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
>>>>> + struct io_pgtable_ops *ops = smmu_domain->pgtbl_ops;
>>>>> + size_t ret;
>>>>> if (!ops)
>>>>> return 0;
>>>>> - return ops->unmap(ops, iova, size);
>>>>> + pm_runtime_get_sync(smmu_domain->smmu->dev);
>>>> Can these map/unmap ops be called from an atomic context? I seem
>>>> to recall that being a problem before.
>>>
>>> That's something which was dropped in the following patch merged in master:
>>> 523d7423e21b iommu/arm-smmu: Remove io-pgtable spinlock
>>>
>>> Looks like we don't need locks here anymore?
>>>
>>
>> While removing the spinlock around the map/unmap path may be one
>> thing, I'm not sure that's all of them. Is there a path from an
>> atomic DMA allocation (GFP_ATOMIC sort of thing) mapped into an
>> IOMMU for a device that can eventually get down to here and
>> attempt to turn a clk on?
>
> Yes, in the DMA path map/unmap will frequently be called from IRQ
> handlers (think e.g. network packets). The whole point of removing the
> lock was to allow multiple maps/unmaps to execute in parallel (since we
> know they will be safely operating on different areas of the pagetable).
> AFAICS this change is going to largely reintroduce that bottleneck via
> dev->power_lock, which is anything but what we want :(
>
Maybe __pm_runtime_resume() needs some sort of fast-path if already
enabled? Or otherwise we need some sort of flag to tell the iommu
that it cannot rely on the unmapping device to be resumed?
BR,
-R
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[PATCH V4 0/6] iommu/arm-smmu: Add runtime pm/sleep support Vivek Gautam <vivek.gautam@codeaurora.org> - 2017-07-06 11:40 +0200
[PATCH V4 2/6] iommu/arm-smmu: Add pm_runtime/sleep ops Vivek Gautam <vivek.gautam@codeaurora.org> - 2017-07-06 11:40 +0200
Re: [PATCH V4 2/6] iommu/arm-smmu: Add pm_runtime/sleep ops Stephen Boyd <sboyd@codeaurora.org> - 2017-07-13 01:00 +0200
Re: [PATCH V4 2/6] iommu/arm-smmu: Add pm_runtime/sleep ops Stephen Boyd <sboyd@codeaurora.org> - 2017-07-13 01:10 +0200
Re: [PATCH V4 2/6] iommu/arm-smmu: Add pm_runtime/sleep ops Vivek Gautam <vivek.gautam@codeaurora.org> - 2017-07-13 06:00 +0200
[PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Vivek Gautam <vivek.gautam@codeaurora.org> - 2017-07-06 11:40 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Stephen Boyd <sboyd@codeaurora.org> - 2017-07-13 01:00 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Vivek Gautam <vivek.gautam@codeaurora.org> - 2017-07-13 07:20 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Sricharan R <sricharan@codeaurora.org> - 2017-07-13 07:40 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Rob Clark <robdclark@gmail.com> - 2017-07-13 14:00 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Marek Szyprowski <m.szyprowski@samsung.com> - 2017-07-13 14:10 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Rob Clark <robdclark@gmail.com> - 2017-07-13 14:20 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Marek Szyprowski <m.szyprowski@samsung.com> - 2017-07-13 14:30 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Sricharan R <sricharan@codeaurora.org> - 2017-07-13 16:00 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Rob Clark <robdclark@gmail.com> - 2017-07-13 17:00 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Will Deacon <will.deacon@arm.com> - 2017-07-14 19:10 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Rob Clark <robdclark@gmail.com> - 2017-07-14 19:50 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Will Deacon <will.deacon@arm.com> - 2017-07-14 20:10 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Rob Clark <robdclark@gmail.com> - 2017-07-14 20:30 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Will Deacon <will.deacon@arm.com> - 2017-07-14 21:10 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Rob Clark <robdclark@gmail.com> - 2017-07-14 21:40 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Sricharan R <sricharan@codeaurora.org> - 2017-07-17 13:50 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Sricharan R <sricharan@codeaurora.org> - 2017-07-17 14:30 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Will Deacon <will.deacon@arm.com> - 2017-07-14 21:40 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Rob Clark <robdclark@gmail.com> - 2017-07-14 21:40 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Vivek Gautam <vivek.gautam@codeaurora.org> - 2017-07-13 16:00 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Vivek Gautam <vivek.gautam@codeaurora.org> - 2017-07-13 16:10 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Stephen Boyd <sboyd@codeaurora.org> - 2017-07-13 08:50 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Robin Murphy <robin.murphy@arm.com> - 2017-07-13 12:00 +0200
Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Rob Clark <robdclark@gmail.com> - 2017-07-13 14:00 +0200
[PATCH V4 4/6] iommu/arm-smmu: Add the device_link between masters and smmu Vivek Gautam <vivek.gautam@codeaurora.org> - 2017-07-06 11:40 +0200
Re: [PATCH V4 4/6] iommu/arm-smmu: Add the device_link between masters and smmu Stephen Boyd <sboyd@codeaurora.org> - 2017-07-13 01:00 +0200
Re: [PATCH V4 4/6] iommu/arm-smmu: Add the device_link between masters and smmu Vivek Gautam <vivek.gautam@codeaurora.org> - 2017-07-13 06:00 +0200
[PATCH V4 5/6] iommu/arm-smmu: Add support for MMU40x/500 clocks Vivek Gautam <vivek.gautam@codeaurora.org> - 2017-07-06 11:40 +0200
Re: [PATCH V4 5/6] iommu/arm-smmu: Add support for MMU40x/500 clocks Rob Herring <robh@kernel.org> - 2017-07-10 05:40 +0200
Re: [PATCH V4 5/6] iommu/arm-smmu: Add support for MMU40x/500 clocks Vivek Gautam <vivek.gautam@codeaurora.org> - 2017-07-11 07:20 +0200
[PATCH V4 6/6] iommu/arm-smmu: Add support for qcom,msm8996-smmu-v2 clocks Vivek Gautam <vivek.gautam@codeaurora.org> - 2017-07-06 11:40 +0200
Re: [PATCH V4 6/6] iommu/arm-smmu: Add support for qcom,msm8996-smmu-v2 clocks Rob Herring <robh@kernel.org> - 2017-07-10 05:50 +0200
Re: [PATCH V4 6/6] iommu/arm-smmu: Add support for qcom,msm8996-smmu-v2 clocks Vivek Gautam <vivek.gautam@codeaurora.org> - 2017-07-10 08:50 +0200
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