Re: [PATCH V3 2/2] scsi: ufs: Add runtime PM support for UFS host controller driver

[Sujit Reddy Thumma <sthumma@codeaurora.org>]

On 7/10/2013 7:01 PM, Seungwon Jeon wrote:
> On Tue, July 09, 2013, Sujit Reddy Thumma wrote:
>> Add runtime PM helpers to suspend/resume UFS controller at runtime.
>> Enable runtime PM by default for pci and platform drivers as the
>> initialized hardware can suspend if it is not used after bootup.
>>
>> Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
>> ---
>>   drivers/scsi/ufs/ufshcd-pci.c    |   65 ++++++++++++++++++++++++++++++++++---
>>   drivers/scsi/ufs/ufshcd-pltfrm.c |   51 +++++++++++++++++++++++++++++-
>>   drivers/scsi/ufs/ufshcd.c        |    8 +++++
>>   3 files changed, 117 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/scsi/ufs/ufshcd-pci.c b/drivers/scsi/ufs/ufshcd-pci.c
>> index 48be39a..7bd8faa 100644
>> --- a/drivers/scsi/ufs/ufshcd-pci.c
>> +++ b/drivers/scsi/ufs/ufshcd-pci.c
>> @@ -35,6 +35,7 @@
>>
>>   #include "ufshcd.h"
>>   #include <linux/pci.h>
>> +#include <linux/pm_runtime.h>
>>
>>   #ifdef CONFIG_PM
>>   /**
>> @@ -44,7 +45,7 @@
>>    *
>>    * Returns -ENOSYS
>>    */
>> -static int ufshcd_pci_suspend(struct pci_dev *pdev, pm_message_t state)
>> +static int ufshcd_pci_suspend(struct device *dev)
>>   {
>>   	/*
>>   	 * TODO:
>> @@ -61,7 +62,7 @@ static int ufshcd_pci_suspend(struct pci_dev *pdev, pm_message_t state)
>>    *
>>    * Returns -ENOSYS
>>    */
>> -static int ufshcd_pci_resume(struct pci_dev *pdev)
>> +static int ufshcd_pci_resume(struct device *dev)
>>   {
>>   	/*
>>   	 * TODO:
>> @@ -71,8 +72,48 @@ static int ufshcd_pci_resume(struct pci_dev *pdev)
>>
>>   	return -ENOSYS;
>>   }
>> +#else
>> +#define ufshcd_pci_suspend	NULL
>> +#define ufshcd_pci_resume	NULL
>>   #endif /* CONFIG_PM */
>>
>> +#ifdef CONFIG_PM_RUNTIME
>> +static int ufshcd_pci_runtime_suspend(struct device *dev)
>> +{
>> +	struct pci_dev *pdev = container_of(dev, struct pci_dev, dev);
>> +	struct ufs_hba *hba = pci_get_drvdata(pdev);
> Can be replaced:
> 	struct ufs_hba *hba = dev_get_drvdata(dev);

Yes.

>
>> +
>> +	if (!hba)
>> +		return 0;
>> +
>> +	return ufshcd_runtime_suspend(hba);
>> +}
>> +static int ufshcd_pci_runtime_resume(struct device *dev)
>> +{
>> +	struct pci_dev *pdev = container_of(dev, struct pci_dev, dev);
>> +	struct ufs_hba *hba = pci_get_drvdata(pdev);
> Same as above.

Okay.

>
>
>> +
>> +	if (!hba)
>> +		return 0;
>> +
>> +	return ufshcd_runtime_resume(hba);
>> +}
>> +static int ufshcd_pci_runtime_idle(struct device *dev)
>> +{
>> +	struct pci_dev *pdev = container_of(dev, struct pci_dev, dev);
>> +	struct ufs_hba *hba = pci_get_drvdata(pdev);
> Same as above.

Okay.
>
>> +
>> +	if (!hba)
>> +		return 0;
>> +
>> +	return ufshcd_runtime_idle(hba);
>> +}
>> +#else /* !CONFIG_PM_RUNTIME */
>> +#define ufshcd_pci_runtime_suspend	NULL
>> +#define ufshcd_pci_runtime_resume	NULL
>> +#define ufshcd_pci_runtime_idle	NULL
>> +#endif /* CONFIG_PM_RUNTIME */
>> +
>>   /**
>>    * ufshcd_pci_shutdown - main function to put the controller in reset state
>>    * @pdev: pointer to PCI device handle
>> @@ -91,6 +132,9 @@ static void ufshcd_pci_remove(struct pci_dev *pdev)
>>   {
>>   	struct ufs_hba *hba = pci_get_drvdata(pdev);
>>
>> +	pm_runtime_forbid(&pdev->dev);
>> +	pm_runtime_get_noresume(&pdev->dev);
>> +
>>   	disable_irq(pdev->irq);
>>   	ufshcd_remove(hba);
>>   	pci_release_regions(pdev);
>> @@ -168,6 +212,8 @@ ufshcd_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>>   	}
>>
>>   	pci_set_drvdata(pdev, hba);
>> +	pm_runtime_put_noidle(&pdev->dev);
>> +	pm_runtime_allow(&pdev->dev);
>>
>>   	return 0;
>>
>> @@ -182,6 +228,14 @@ out_error:
>>   	return err;
>>   }
>>
>> +static const struct dev_pm_ops ufshcd_pci_pm_ops = {
>> +	.suspend	= ufshcd_pci_suspend,
>> +	.resume		= ufshcd_pci_resume,
>> +	.runtime_suspend = ufshcd_pci_runtime_suspend,
>> +	.runtime_resume  = ufshcd_pci_runtime_resume,
>> +	.runtime_idle    = ufshcd_pci_runtime_idle,
>> +};
>> +
>>   static DEFINE_PCI_DEVICE_TABLE(ufshcd_pci_tbl) = {
>>   	{ PCI_VENDOR_ID_SAMSUNG, 0xC00C, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 },
>>   	{ }	/* terminate list */
>> @@ -195,10 +249,9 @@ static struct pci_driver ufshcd_pci_driver = {
>>   	.probe = ufshcd_pci_probe,
>>   	.remove = ufshcd_pci_remove,
>>   	.shutdown = ufshcd_pci_shutdown,
>> -#ifdef CONFIG_PM
>> -	.suspend = ufshcd_pci_suspend,
>> -	.resume = ufshcd_pci_resume,
>> -#endif
>> +	.driver = {
>> +		.pm = &ufshcd_pci_pm_ops
>> +	},
>>   };
>>
>>   module_pci_driver(ufshcd_pci_driver);
>> diff --git a/drivers/scsi/ufs/ufshcd-pltfrm.c b/drivers/scsi/ufs/ufshcd-pltfrm.c
>> index c42db40..b1f2605 100644
>> --- a/drivers/scsi/ufs/ufshcd-pltfrm.c
>> +++ b/drivers/scsi/ufs/ufshcd-pltfrm.c
>> @@ -34,6 +34,7 @@
>>    */
>>
>>   #include <linux/platform_device.h>
>> +#include <linux/pm_runtime.h>
>>
>>   #include "ufshcd.h"
>>
>> @@ -87,6 +88,43 @@ static int ufshcd_pltfrm_resume(struct device *dev)
>>   #define ufshcd_pltfrm_resume	NULL
>>   #endif
>>
>> +#ifdef CONFIG_PM_RUNTIME
>> +static int ufshcd_pltfrm_runtime_suspend(struct device *dev)
>> +{
>> +	struct platform_device *pdev = to_platform_device(dev);
>> +	struct ufs_hba *hba =  platform_get_drvdata(pdev);
> Same as above.
Okay.

>
>> +
>> +	if (!hba)
>> +		return 0;
>> +
>> +	return ufshcd_runtime_suspend(hba);
>> +}
>> +static int ufshcd_pltfrm_runtime_resume(struct device *dev)
>> +{
>> +	struct platform_device *pdev = to_platform_device(dev);
>> +	struct ufs_hba *hba =  platform_get_drvdata(pdev);
> Same as above.

Okay.

>
>> +
>> +	if (!hba)
>> +		return 0;
>> +
>> +	return ufshcd_runtime_resume(hba);
>> +}
>> +static int ufshcd_pltfrm_runtime_idle(struct device *dev)
>> +{
>> +	struct platform_device *pdev = to_platform_device(dev);
>> +	struct ufs_hba *hba =  platform_get_drvdata(pdev);
> Same as above.
Okay.
>
>> +
>> +	if (!hba)
>> +		return 0;
>> +
>> +	return ufshcd_runtime_idle(hba);
>> +}
>> +#else /* !CONFIG_PM_RUNTIME */
>> +#define ufshcd_pltfrm_runtime_suspend	NULL
>> +#define ufshcd_pltfrm_runtime_resume	NULL
>> +#define ufshcd_pltfrm_runtime_idle	NULL
>> +#endif /* CONFIG_PM_RUNTIME */
>> +
>>   /**
>>    * ufshcd_pltfrm_probe - probe routine of the driver
>>    * @pdev: pointer to Platform device handle
>> @@ -122,14 +160,20 @@ static int ufshcd_pltfrm_probe(struct platform_device *pdev)
>>   		goto out;
>>   	}
>>
>> +	pm_runtime_set_active(&pdev->dev);
>> +	pm_runtime_enable(&pdev->dev);
>> +
>>   	err = ufshcd_init(dev, &hba, mmio_base, irq);
>>   	if (err) {
>>   		dev_err(dev, "Intialization failed\n");
>> -		goto out;
>> +		goto out_disable_rpm;
>>   	}
>>
>>   	platform_set_drvdata(pdev, hba);
>>
>> +out_disable_rpm:
>> +	pm_runtime_disable(&pdev->dev);
>> +	pm_runtime_set_suspended(&pdev->dev);
>>   out:
>>   	return err;
>>   }
>> @@ -144,6 +188,8 @@ static int ufshcd_pltfrm_remove(struct platform_device *pdev)
>>   {
>>   	struct ufs_hba *hba =  platform_get_drvdata(pdev);
>>
>> +	pm_runtime_get_sync(&(pdev)->dev);
>> +
>>   	disable_irq(hba->irq);
>>   	ufshcd_remove(hba);
>>   	return 0;
>> @@ -157,6 +203,9 @@ static const struct of_device_id ufs_of_match[] = {
>>   static const struct dev_pm_ops ufshcd_dev_pm_ops = {
>>   	.suspend	= ufshcd_pltfrm_suspend,
>>   	.resume		= ufshcd_pltfrm_resume,
>> +	.runtime_suspend = ufshcd_pltfrm_runtime_suspend,
>> +	.runtime_resume  = ufshcd_pltfrm_runtime_resume,
>> +	.runtime_idle    = ufshcd_pltfrm_runtime_idle,
>>   };
>>
>>   static struct platform_driver ufshcd_pltfrm_driver = {
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index a25de66..af7d01d 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -2230,6 +2230,7 @@ static void ufshcd_exception_event_handler(struct work_struct *work)
>>   	u32 status = 0;
>>   	hba = container_of(work, struct ufs_hba, eeh_work);
>>
>> +	pm_runtime_get_sync(hba->dev);
>>   	err = ufshcd_get_ee_status(hba, &status);
>>   	if (err) {
>>   		dev_err(hba->dev, "%s: failed to get exception status %d\n",
>> @@ -2245,6 +2246,7 @@ static void ufshcd_exception_event_handler(struct work_struct *work)
>>   					__func__, err);
>>   	}
>>   out:
>> +	pm_runtime_put_sync(hba->dev);
> In ufshcd_urgent_bkops, ufshcd_enable_auto_bkops will be executed.

That should be still fine. We have necessary checks in
ufshcd_enable_auto_bkops() to skip enabling if already enabled.


>
>>   	return;
>>   }
>>
>> @@ -2257,9 +2259,11 @@ static void ufshcd_fatal_err_handler(struct work_struct *work)
>>   	struct ufs_hba *hba;
>>   	hba = container_of(work, struct ufs_hba, feh_workq);
>>
>> +	pm_runtime_get_sync(hba->dev);
>>   	/* check if reset is already in progress */
>>   	if (hba->ufshcd_state != UFSHCD_STATE_RESET)
>>   		ufshcd_do_reset(hba);
>> +	pm_runtime_put_sync(hba->dev);
>>   }
>>
>>   /**
>> @@ -2562,6 +2566,7 @@ static void ufshcd_async_scan(void *data, async_cookie_t cookie)
>>   	hba->auto_bkops_enabled = false;
> In the end of 'ufshcd_init', pm_runtime_get_sync is called, hence auto_bkops_enabled may has false.
> 'auto_bkops_enabled = false' is needed?

The device may undergo reset before this, and so the internal device
flag may be reset to default (which is auto bkops enabled). The two
steps here - auto_bkops_enabled = false and  ufshcd_enabled_auto_bkops()
ensure that s/w variables are aligned with h/w state.

>
>>   	ufshcd_enable_auto_bkops(hba);
> Should 'ufshcd_enable_auto_bkops' be done here?

Not really needed. But just to make sure that bootloader didn't mess
up with it and the s/w variables are still pointing that auto_bkops is
disabled.

>
>>   	scsi_scan_host(hba->host);
>> +	pm_runtime_put_sync(hba->dev);
> Practically, after pm_runtime_put_sync, ufshcd_enable_auto_bkops will be executed.
> Then, it's duplication of ufshcd_enable_auto_bkops?
> ufshcd_enable_auto_bkops is already done above.

ufshcd_enable_auto_bkops() has necessary checks to make sure that we
are not re-enabling if already enabled.

One thing to note here is that pm_runtime_get_sync() and put_sync()
are independent of the bkops status. The runtime PM make sures that
after device idle'd suspend is triggered. What we do in suspend routine
is not of a concern. Moreover, pm_runtime_get_sync() calls are just
dummy calls when CONFIG_RUNTIME_PM is disabled so we can't assume
anything with that and make the sequence complex.

>
> And actual routine of scsi_scan_host performs asynchronously.
> That means it's not completed. So, pm_runtime_put_sync looks like improper here.

After this operation, the device is sure to respond to any command
including those required for bkops. So put_sync is proper here.
If there is any new command issued to the controller as part
of scsi_scan_host() and the host is already suspended it will be
resumed, we are not breaking the parent-child relation ship so any new
device when added as a child triggers runtime resume for parent (if
suspended).

>
>>   out:
>>   	return;
>>   }
>> @@ -2783,6 +2788,9 @@ int ufshcd_init(struct device *dev, struct ufs_hba **hba_handle,
>>
>>   	*hba_handle = hba;
>>
>> +	/* Hold auto suspend until async scan completes */
> What's meaning of comment?

We haven't yet initialized the device so runtime PM suspned/resume may
fail. Until async scan is scheduled we take PM reference count to make
sure device is not suspended inbetween.


>
> Thanks,
> Seungwon Jeon
>
>> +	pm_runtime_get_sync(dev);
>> +
>>   	async_schedule(ufshcd_async_scan, hba);
>>
>>   	return 0;
>> --
>> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
>> of Code Aurora Forum, hosted by The Linux Foundation.
>>
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>

-- 
Regards,
Sujit