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SubjectRe: [PATCH v12 1/4] iommu/arm-smmu: Add pm_runtime/sleep ops
Hi Rafael,


On Wed, Jul 11, 2018 at 3:20 PM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> On Sunday, July 8, 2018 7:34:10 PM CEST Vivek Gautam wrote:
>> From: Sricharan R <sricharan@codeaurora.org>
>>
>> The smmu needs to be functional only when the respective
>> master's using it are active. The device_link feature
>> helps to track such functional dependencies, so that the
>> iommu gets powered when the master device enables itself
>> using pm_runtime. So by adapting the smmu driver for
>> runtime pm, above said dependency can be addressed.
>>
>> This patch adds the pm runtime/sleep callbacks to the
>> driver and also the functions to parse the smmu clocks
>> from DT and enable them in resume/suspend.
>>
>> Signed-off-by: Sricharan R <sricharan@codeaurora.org>
>> Signed-off-by: Archit Taneja <architt@codeaurora.org>
>> [vivek: Clock rework to request bulk of clocks]
>> Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
>> Reviewed-by: Tomasz Figa <tfiga@chromium.org>
>> ---
>>
>> - No change since v11.
>>
>> drivers/iommu/arm-smmu.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++--
>> 1 file changed, 58 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
>> index f7a96bcf94a6..a01d0dde21dd 100644
>> --- a/drivers/iommu/arm-smmu.c
>> +++ b/drivers/iommu/arm-smmu.c
>> @@ -48,6 +48,7 @@
>> #include <linux/of_iommu.h>
>> #include <linux/pci.h>
>> #include <linux/platform_device.h>
>> +#include <linux/pm_runtime.h>
>> #include <linux/slab.h>
>> #include <linux/spinlock.h>
>>
>> @@ -205,6 +206,8 @@ struct arm_smmu_device {
>> u32 num_global_irqs;
>> u32 num_context_irqs;
>> unsigned int *irqs;
>> + struct clk_bulk_data *clks;
>> + int num_clks;
>>
>> u32 cavium_id_base; /* Specific to Cavium */
>>
>> @@ -1897,10 +1900,12 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
>> struct arm_smmu_match_data {
>> enum arm_smmu_arch_version version;
>> enum arm_smmu_implementation model;
>> + const char * const *clks;
>> + int num_clks;
>> };
>>
>> #define ARM_SMMU_MATCH_DATA(name, ver, imp) \
>> -static struct arm_smmu_match_data name = { .version = ver, .model = imp }
>> +static const struct arm_smmu_match_data name = { .version = ver, .model = imp }
>>
>> ARM_SMMU_MATCH_DATA(smmu_generic_v1, ARM_SMMU_V1, GENERIC_SMMU);
>> ARM_SMMU_MATCH_DATA(smmu_generic_v2, ARM_SMMU_V2, GENERIC_SMMU);
>> @@ -1919,6 +1924,23 @@ static const struct of_device_id arm_smmu_of_match[] = {
>> };
>> MODULE_DEVICE_TABLE(of, arm_smmu_of_match);
>>
>> +static void arm_smmu_fill_clk_data(struct arm_smmu_device *smmu,
>> + const char * const *clks)
>> +{
>> + int i;
>> +
>> + if (smmu->num_clks < 1)
>> + return;
>> +
>> + smmu->clks = devm_kcalloc(smmu->dev, smmu->num_clks,
>> + sizeof(*smmu->clks), GFP_KERNEL);
>> + if (!smmu->clks)
>> + return;
>> +
>> + for (i = 0; i < smmu->num_clks; i++)
>> + smmu->clks[i].id = clks[i];
>> +}
>> +
>> #ifdef CONFIG_ACPI
>> static int acpi_smmu_get_data(u32 model, struct arm_smmu_device *smmu)
>> {
>> @@ -2001,6 +2023,9 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev,
>> data = of_device_get_match_data(dev);
>> smmu->version = data->version;
>> smmu->model = data->model;
>> + smmu->num_clks = data->num_clks;
>> +
>> + arm_smmu_fill_clk_data(smmu, data->clks);
>>
>> parse_driver_options(smmu);
>>
>> @@ -2099,6 +2124,14 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
>> smmu->irqs[i] = irq;
>> }
>>
>> + err = devm_clk_bulk_get(smmu->dev, smmu->num_clks, smmu->clks);
>> + if (err)
>> + return err;
>> +
>> + err = clk_bulk_prepare(smmu->num_clks, smmu->clks);
>> + if (err)
>> + return err;
>> +
>> err = arm_smmu_device_cfg_probe(smmu);
>> if (err)
>> return err;
>> @@ -2181,6 +2214,9 @@ static int arm_smmu_device_remove(struct platform_device *pdev)
>>
>> /* Turn the thing off */
>> writel(sCR0_CLIENTPD, ARM_SMMU_GR0_NS(smmu) + ARM_SMMU_GR0_sCR0);
>> +
>> + clk_bulk_unprepare(smmu->num_clks, smmu->clks);
>> +
>> return 0;
>> }
>>
>> @@ -2197,7 +2233,27 @@ static int __maybe_unused arm_smmu_pm_resume(struct device *dev)
>> return 0;
>> }
>>
>> -static SIMPLE_DEV_PM_OPS(arm_smmu_pm_ops, NULL, arm_smmu_pm_resume);
>> +static int __maybe_unused arm_smmu_runtime_resume(struct device *dev)
>> +{
>> + struct arm_smmu_device *smmu = dev_get_drvdata(dev);
>> +
>> + return clk_bulk_enable(smmu->num_clks, smmu->clks);
>> +}
>> +
>> +static int __maybe_unused arm_smmu_runtime_suspend(struct device *dev)
>> +{
>> + struct arm_smmu_device *smmu = dev_get_drvdata(dev);
>> +
>> + clk_bulk_disable(smmu->num_clks, smmu->clks);
>> +
>> + return 0;
>> +}
>> +
>> +static const struct dev_pm_ops arm_smmu_pm_ops = {
>> + SET_SYSTEM_SLEEP_PM_OPS(NULL, arm_smmu_pm_resume)
>
> This is suspicious.
>
> If you need a runtime suspend method, why do you think that it is not necessary
> to suspend the device during system-wide transitions?

Okay, so you suggest to put clock disabling in say arm_smmu_pm_suspend()?
In that case the clocks have to be enabled in the resume path too.

I remember Tomasz pointed to that we shouldn't need clock enable in resume
path [1].

[1] https://lkml.org/lkml/2018/3/15/60


Best regards
Vivek

>
>> + SET_RUNTIME_PM_OPS(arm_smmu_runtime_suspend,
>> + arm_smmu_runtime_resume, NULL)
>> +};
>>
>> static struct platform_driver arm_smmu_driver = {
>> .driver = {
>>
>
>



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