From: Vivek Gautam <vivek.gautam@codeaurora.org>
To: Will Deacon <will.deacon@arm.com>
Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
David Brown <david.brown@linaro.org>,
"list@263.net:IOMMU DRIVERS <iommu@lists.linux-foundation.org>,
Joerg Roedel <joro@8bytes.org>,
" <iommu@lists.linux-foundation.org>,
robh+dt <robh+dt@kernel.org>, Andy Gross <agross@kernel.org>,
Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH v3 1/4] firmware: qcom_scm-64: Add atomic version of qcom_scm_call
Date: Wed, 19 Jun 2019 17:04:39 +0530 [thread overview]
Message-ID: <CAFp+6iEwN6jeEGNxKVU5_i5NxdEbuF2ZggegEJZ1Rq6F=H34jg@mail.gmail.com> (raw)
In-Reply-To: <20190618175536.GI4270@fuggles.cambridge.arm.com>
On Tue, Jun 18, 2019 at 11:25 PM Will Deacon <will.deacon@arm.com> wrote:
>
> On Wed, Jun 12, 2019 at 12:45:51PM +0530, Vivek Gautam wrote:
> > There are scnenarios where drivers are required to make a
> > scm call in atomic context, such as in one of the qcom's
> > arm-smmu-500 errata [1].
> >
> > [1] ("https://source.codeaurora.org/quic/la/kernel/msm-4.9/commit/
> > drivers/iommu/arm-smmu.c?h=CogSystems-msm-49/
> > msm-4.9&id=da765c6c75266b38191b38ef086274943f353ea7")
> >
> > Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
> > Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> > ---
> > drivers/firmware/qcom_scm-64.c | 136 ++++++++++++++++++++++++++++-------------
> > 1 file changed, 92 insertions(+), 44 deletions(-)
> >
> > diff --git a/drivers/firmware/qcom_scm-64.c b/drivers/firmware/qcom_scm-64.c
> > index 91d5ad7cf58b..b6dca32c5ac4 100644
> > --- a/drivers/firmware/qcom_scm-64.c
> > +++ b/drivers/firmware/qcom_scm-64.c
[snip]
> > +
> > +static void qcom_scm_call_do(const struct qcom_scm_desc *desc,
> > + struct arm_smccc_res *res, u32 fn_id,
> > + u64 x5, bool atomic)
> > +{
>
> Maybe pass in the call type (ARM_SMCCC_FAST_CALL vs ARM_SMCCC_STD_CALL)
> instead of "bool atomic"? Would certainly make the callsites easier to
> understand.
Sure, will do that.
>
> > + int retry_count = 0;
> > +
> > + if (!atomic) {
> > + do {
> > + mutex_lock(&qcom_scm_lock);
> > +
> > + __qcom_scm_call_do(desc, res, fn_id, x5,
> > + ARM_SMCCC_STD_CALL);
> > +
> > + mutex_unlock(&qcom_scm_lock);
> > +
> > + if (res->a0 == QCOM_SCM_V2_EBUSY) {
> > + if (retry_count++ > QCOM_SCM_EBUSY_MAX_RETRY)
> > + break;
> > + msleep(QCOM_SCM_EBUSY_WAIT_MS);
> > + }
> > + } while (res->a0 == QCOM_SCM_V2_EBUSY);
> > + } else {
> > + __qcom_scm_call_do(desc, res, fn_id, x5, ARM_SMCCC_FAST_CALL);
> > + }
>
> Is it safe to make concurrent FAST calls?
I better add a spinlock here.
Thanks & regards
Vivek
>
> Will
> _______________________________________________
> iommu mailing list
> iommu@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
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next prev parent reply other threads:[~2019-06-19 11:34 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-12 7:15 [PATCH v3 0/4] Qcom smmu-500 wait-for-safe handling for sdm845 Vivek Gautam
2019-06-12 7:15 ` [PATCH v3 1/4] firmware: qcom_scm-64: Add atomic version of qcom_scm_call Vivek Gautam
2019-06-18 17:55 ` Will Deacon
2019-06-19 11:34 ` Vivek Gautam [this message]
2019-08-05 22:27 ` Bjorn Andersson
2019-08-08 11:35 ` Vivek Gautam
2019-08-08 16:30 ` Will Deacon
2019-06-12 7:15 ` [PATCH v3 2/4] firmware/qcom_scm: Add scm call to handle smmu errata Vivek Gautam
2019-06-12 7:15 ` [PATCH v3 3/4] iommu/arm-smmu: Add support to handle Qcom's wait-for-safe logic Vivek Gautam
2019-06-14 4:05 ` Bjorn Andersson
2019-06-14 9:18 ` Vivek Gautam
2019-06-18 17:52 ` Will Deacon
2019-06-24 10:28 ` Vivek Gautam
2019-06-24 17:03 ` Will Deacon
2019-06-25 7:04 ` Vivek Gautam
2019-06-25 13:39 ` Will Deacon
2019-06-26 6:33 ` Vivek Gautam
2019-06-26 14:48 ` Will Deacon
2019-06-27 7:05 ` Vivek Gautam
2019-06-12 7:15 ` [PATCH v3 4/4] arm64: dts/sdm845: Enable FW implemented safe sequence handler on MTP Vivek Gautam
2019-06-14 4:06 ` Bjorn Andersson
2019-06-14 9:01 ` Vivek Gautam
2019-08-05 22:26 ` Bjorn Andersson
2019-08-11 16:08 ` Vivek Gautam
2019-08-11 19:01 ` Bjorn Andersson
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