From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: Will Deacon <will@kernel.org>
Cc: mark.rutland@arm.com, iommu@lists.linux-foundation.org,
lorenzo.pieralisi@arm.com, robin.murphy@arm.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] perf/smmuv3: Allow sharing MMIO registers with the SMMU driver
Date: Wed, 20 May 2020 14:44:13 +0200 [thread overview]
Message-ID: <20200520124413.GA2512145@myrica> (raw)
In-Reply-To: <20200520122453.GB25815@willie-the-truck>
On Wed, May 20, 2020 at 01:24:53PM +0100, Will Deacon wrote:
> On Tue, Apr 21, 2020 at 05:57:46PM +0200, Jean-Philippe Brucker wrote:
> > Some Arm SMMUv3 implementations, for example Arm CoreLink MMU-600, embed
> > the PMCG registers into the SMMU MMIO regions. It currently causes probe
> > failure because the PMU and SMMU drivers request overlapping resources.
> >
> > Avoid the conflict by calling devm_ioremap() directly from the PMU
> > driver. We loose some sanity-checking of the memory map provided by
> > firmware, which doesn't seem catastrophic.
> >
> > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > ---
> >
> > So this is the simplest solution, and I don't think we're missing much
> > by skipping the resource reservation. I've also been exploring a more
> > complex approach [1] which has the SMMU driver perform resource
> > reservation on behalf of the PMU driver, but I'm not sure it's
> > necessary.
> >
> > Please test, I've only tried the RevC FastModel using devicetree so far.
> >
> > [1] https://jpbrucker.net/git/linux/log/?h=smmu/pmu
> > ---
> > drivers/perf/arm_smmuv3_pmu.c | 28 +++++++++++++++++++++-------
> > 1 file changed, 21 insertions(+), 7 deletions(-)
>
> Is this patch still needed? I can't quite follow from the discussion.
No, it is superseded by "[PATCH v2] iommu/arm-smmu-v3: Don't reserve
implementation defined register space" that you applied yesterday
(Thanks!)
Jean
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prev parent reply other threads:[~2020-05-20 12:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-21 15:57 [PATCH] perf/smmuv3: Allow sharing MMIO registers with the SMMU driver Jean-Philippe Brucker
2020-04-21 17:25 ` Robin Murphy
2020-04-28 18:10 ` Tuan Phan
2020-04-29 7:21 ` Jean-Philippe Brucker
2020-04-29 18:01 ` Tuan Phan
2020-05-06 16:11 ` Jean-Philippe Brucker
2020-05-20 12:24 ` Will Deacon
2020-05-20 12:44 ` Jean-Philippe Brucker [this message]
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