linux-kernel - Re: [PATCH v16 2/5] iommu/arm-smmu: Invoke pm

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Message-ID: <20181001125854.GB31488@arm.com>
Date:   Mon, 1 Oct 2018 13:58:55 +0100
From:   Will Deacon <will.deacon@....com>
To:     Vivek Gautam <vivek.gautam@...eaurora.org>
Cc:     joro@...tes.org, robh+dt@...nel.org, robin.murphy@....com,
        iommu@...ts.linux-foundation.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, alex.williamson@...hat.com,
        mark.rutland@....com, rjw@...ysocki.net, robdclark@...il.com,
        linux-pm@...r.kernel.org, freedreno@...ts.freedesktop.org,
        sboyd@...nel.org, tfiga@...omium.org, jcrouse@...eaurora.org,
        sricharan@...eaurora.org, m.szyprowski@...sung.com,
        architt@...eaurora.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v16 2/5] iommu/arm-smmu: Invoke pm_runtime during probe,
 add/remove device

Hi Vivek,

On Thu, Aug 30, 2018 at 08:15:38PM +0530, Vivek Gautam wrote:
> From: Sricharan R <sricharan@...eaurora.org>
> 
> The smmu device probe/remove and add/remove master device callbacks
> gets called when the smmu is not linked to its master, that is without
> the context of the master device. So calling runtime apis in those places
> separately.
> Global locks are also initialized before enabling runtime pm as the
> runtime_resume() calls device_reset() which does tlb_sync_global()
> that ultimately requires locks to be initialized.
> 
> Signed-off-by: Sricharan R <sricharan@...eaurora.org>
> [vivek: Cleanup pm runtime calls]
> Signed-off-by: Vivek Gautam <vivek.gautam@...eaurora.org>
> Reviewed-by: Tomasz Figa <tfiga@...omium.org>
> Tested-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> ---
>  drivers/iommu/arm-smmu.c | 89 +++++++++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 81 insertions(+), 8 deletions(-)

This doesn't apply on my tree[1], possibly because I've got Robin's non-strict
invalidation queued there. However, that got me thinking -- how does this
work in conjunction with the timer-based TLB invalidation? Do we need to
rpm_{get,put} around flush_iotlb_all()? If so, do we still need the calls
in map/unmap when non-strict mode is in use?

Will

[1] https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=for-joerg/arm-smmu/updates