linux-kernel - Re: [PATCH v2 3/3] skd: use generic power management

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Message-ID: <CY4PR04MB375176CACBFC3C2BEBE6D0AAE7780@CY4PR04MB3751.namprd04.prod.outlook.com>
Date:   Tue, 21 Jul 2020 02:57:28 +0000
From:   Damien Le Moal <Damien.LeMoal@....com>
To:     Vaibhav Gupta <vaibhavgupta40@...il.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Bjorn Helgaas <bjorn@...gaas.com>,
        Vaibhav Gupta <vaibhav.varodek@...il.com>,
        Jens Axboe <axboe@...nel.dk>,
        Joshua Morris <josh.h.morris@...ibm.com>,
        Philip Kelleher <pjk1939@...ux.ibm.com>
CC:     "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-kernel-mentees@...ts.linuxfoundation.org" 
        <linux-kernel-mentees@...ts.linuxfoundation.org>,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH v2 3/3] skd: use generic power management

On 2020/07/20 22:32, Vaibhav Gupta wrote:
> Drivers using legacy PM have to manage PCI states and device's PM states
> themselves. They also need to take care of configuration registers.
> 
> With improved and powerful support of generic PM, PCI Core takes care of
> above mentioned, device-independent, jobs.
> 
> This driver makes use of PCI helper functions like
> pci_save/restore_state(), pci_enable/disable_device(),
> pci_request/release_regions(), pci_set_power_state() and
> pci_set_master() to do required operations. In generic mode, they are no
> longer needed.
> 
> Change function parameter in both .suspend() and .resume() to
> "struct device*" type. Use to_pci_dev() to get "struct pci_dev*" variable.

This commit message is rather vague, and the last sentence actually does not
describe correctly the change. What about something very simple, yet clear, like
this:

skd: use generic power management

Switch from the legacy .suspend()/.resume() power management interface to the
generic power management interface using the single .driver.pm() method. This
avoids the need for the driver to directly call most of the PCI helper functions
and device power state control functions as the generic power management
interface takes care of the necessary operations.

> 
> Compile-tested only.
> 
> Signed-off-by: Vaibhav Gupta <vaibhavgupta40@...il.com>
> ---
>  drivers/block/skd_main.c | 30 ++++++++----------------------
>  1 file changed, 8 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/block/skd_main.c b/drivers/block/skd_main.c
> index 51569c199a6c..7f2d42900b38 100644
> --- a/drivers/block/skd_main.c
> +++ b/drivers/block/skd_main.c
> @@ -3315,10 +3315,11 @@ static void skd_pci_remove(struct pci_dev *pdev)
>  	return;
>  }
>  
> -static int skd_pci_suspend(struct pci_dev *pdev, pm_message_t state)
> +static int __maybe_unused skd_pci_suspend(struct device *dev)
>  {
>  	int i;
>  	struct skd_device *skdev;
> +	struct pci_dev *pdev = to_pci_dev(dev);
>  
>  	skdev = pci_get_drvdata(pdev);
>  	if (!skdev) {
> @@ -3337,18 +3338,15 @@ static int skd_pci_suspend(struct pci_dev *pdev, pm_message_t state)
>  	if (skdev->pcie_error_reporting_is_enabled)
>  		pci_disable_pcie_error_reporting(pdev);
>  
> -	pci_release_regions(pdev);
> -	pci_save_state(pdev);
> -	pci_disable_device(pdev);
> -	pci_set_power_state(pdev, pci_choose_state(pdev, state));
>  	return 0;
>  }
>  
> -static int skd_pci_resume(struct pci_dev *pdev)
> +static int __maybe_unused skd_pci_resume(struct device *dev)
>  {
>  	int i;
>  	int rc = 0;
>  	struct skd_device *skdev;
> +	struct pci_dev *pdev = to_pci_dev(dev);
>  
>  	skdev = pci_get_drvdata(pdev);
>  	if (!skdev) {
> @@ -3356,16 +3354,8 @@ static int skd_pci_resume(struct pci_dev *pdev)
>  		return -1;
>  	}
>  
> -	pci_set_power_state(pdev, PCI_D0);
> -	pci_enable_wake(pdev, PCI_D0, 0);
> -	pci_restore_state(pdev);
> +	device_wakeup_disable(dev);
>  
> -	rc = pci_enable_device(pdev);
> -	if (rc)
> -		return rc;
> -	rc = pci_request_regions(pdev, DRV_NAME);
> -	if (rc)
> -		goto err_out;
>  	rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
>  	if (rc)
>  		rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
> @@ -3374,7 +3364,6 @@ static int skd_pci_resume(struct pci_dev *pdev)
>  		goto err_out_regions;
>  	}
>  
> -	pci_set_master(pdev);
>  	rc = pci_enable_pcie_error_reporting(pdev);
>  	if (rc) {
>  		dev_err(&pdev->dev,
> @@ -3427,10 +3416,6 @@ static int skd_pci_resume(struct pci_dev *pdev)
>  		pci_disable_pcie_error_reporting(pdev);
>  
>  err_out_regions:
> -	pci_release_regions(pdev);
> -
> -err_out:
> -	pci_disable_device(pdev);
>  	return rc;
>  }
>  
> @@ -3450,13 +3435,14 @@ static void skd_pci_shutdown(struct pci_dev *pdev)
>  	skd_stop_device(skdev);
>  }
>  
> +static SIMPLE_DEV_PM_OPS(skd_pci_pm_ops, skd_pci_suspend, skd_pci_resume);
> +
>  static struct pci_driver skd_driver = {
>  	.name		= DRV_NAME,
>  	.id_table	= skd_pci_tbl,
>  	.probe		= skd_pci_probe,
>  	.remove		= skd_pci_remove,
> -	.suspend	= skd_pci_suspend,
> -	.resume		= skd_pci_resume,
> +	.driver.pm	= &skd_pci_pm_ops,
>  	.shutdown	= skd_pci_shutdown,
>  };
>  
> 

Apart from the commit message, this looks OK to me.
I will give this a spin today on the hardware to check.


-- 
Damien Le Moal
Western Digital Research