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Tue, 27 Jul 2021 10:26:29 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m8KHh-00EPf9-AZ for linux-arm-kernel@lists.infradead.org; Tue, 27 Jul 2021 10:26:02 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0245E1FB; Tue, 27 Jul 2021 03:25:58 -0700 (PDT) Received: from [10.57.36.146] (unknown [10.57.36.146]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 513083F73D; Tue, 27 Jul 2021 03:25:56 -0700 (PDT) Subject: Re: [PATCH] iommu/arm-smmu: Add clk_bulk_{prepare/unprepare} to system pm callbacks To: Sai Prakash Ranjan , Will Deacon , Joerg Roedel , Rajendra Nayak , Taniya Das , srimuc Cc: linux-arm-msm@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <20210727093322.13202-1-saiprakash.ranjan@codeaurora.org> From: Robin Murphy Message-ID: <955a3034-f7e7-f8f9-4abd-b65efbfbb404@arm.com> Date: Tue, 27 Jul 2021 11:25:50 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210727093322.13202-1-saiprakash.ranjan@codeaurora.org> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210727_032601_551096_ABE5D6A2 X-CRM114-Status: GOOD ( 23.60 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2021-07-27 10:33, Sai Prakash Ranjan wrote: > Some clocks for SMMU can have parent as XO such as gpu_cc_hub_cx_int_clk > of GPU SMMU in QTI SC7280 SoC and in order to enter deep sleep states in > such cases, we would need to drop the XO clock vote in unprepare call and > this unprepare callback for XO is in RPMh (Resource Power Manager-Hardened) > clock driver which controls RPMh managed clock resources for new QTI SoCs > and is a blocking call. > > Given we cannot have a sleeping calls such as clk_bulk_prepare() and > clk_bulk_unprepare() in arm-smmu runtime pm callbacks since the iommu > operations like map and unmap can be in atomic context and are in fast > path, add this prepare and unprepare call to drop the XO vote only for > system pm callbacks since it is not a fast path and we expect the system > to enter deep sleep states with system pm as opposed to runtime pm. > > This is a similar sequence of clock requests (prepare,enable and > disable,unprepare) in arm-smmu probe and remove. Nope. We call arm_smmu_rpm_get(), which may resume the device, from atomic contexts. clk_prepare() may sleep. This doesn't work. Robin. > Signed-off-by: Sai Prakash Ranjan > Co-developed-by: Rajendra Nayak > Signed-off-by: Rajendra Nayak > --- > drivers/iommu/arm/arm-smmu/arm-smmu.c | 20 ++++++++++++++++++-- > 1 file changed, 18 insertions(+), 2 deletions(-) > > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c > index d3c6f54110a5..9561ba4c5d39 100644 > --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c > @@ -2277,6 +2277,13 @@ static int __maybe_unused arm_smmu_runtime_suspend(struct device *dev) > > static int __maybe_unused arm_smmu_pm_resume(struct device *dev) > { > + int ret; > + struct arm_smmu_device *smmu = dev_get_drvdata(dev); > + > + ret = clk_bulk_prepare(smmu->num_clks, smmu->clks); > + if (ret) > + return ret; > + > if (pm_runtime_suspended(dev)) > return 0; > > @@ -2285,10 +2292,19 @@ static int __maybe_unused arm_smmu_pm_resume(struct device *dev) > > static int __maybe_unused arm_smmu_pm_suspend(struct device *dev) > { > + int ret = 0; > + struct arm_smmu_device *smmu = dev_get_drvdata(dev); > + > if (pm_runtime_suspended(dev)) > - return 0; > + goto clk_unprepare; > > - return arm_smmu_runtime_suspend(dev); > + ret = arm_smmu_runtime_suspend(dev); > + if (ret) > + return ret; > + > +clk_unprepare: > + clk_bulk_unprepare(smmu->num_clks, smmu->clks); > + return ret; > } > > static const struct dev_pm_ops arm_smmu_pm_ops = { > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel