linux-kernel - Re: [PATCH v1] dmaengine: pch_dma: use generic power management

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Date:   Mon, 27 Jul 2020 14:26:21 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Vaibhav Gupta <vaibhavgupta40@...il.com>
Cc:     Bjorn Helgaas <helgaas@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Bjorn Helgaas <bjorn@...gaas.com>,
        Vaibhav Gupta <vaibhav.varodek@...il.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Shuah Khan <skhan@...uxfoundation.org>,
        linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        dmaengine@...r.kernel.org
Subject: Re: [PATCH v1] dmaengine: pch_dma: use generic power management

Hi Vaibhav,

On 20-07-20, 17:07, 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(),
> and pci_set_power_state() 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 dev_get_drvdata() to get drv data.

You are doing too many things in One patch. Do consider splitting them
up to a change per patch. for example using __maybe could be one patch,
removing code is suspend-resume callbacks would be other one.
> 
> Compile-tested only.

I would like to see some testing before we merge this

> 
> Signed-off-by: Vaibhav Gupta <vaibhavgupta40@...il.com>
> ---
>  drivers/dma/pch_dma.c | 35 +++++++++--------------------------
>  1 file changed, 9 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/dma/pch_dma.c b/drivers/dma/pch_dma.c
> index a3b0b4c56a19..e93005837e3f 100644
> --- a/drivers/dma/pch_dma.c
> +++ b/drivers/dma/pch_dma.c
> @@ -735,8 +735,7 @@ static irqreturn_t pd_irq(int irq, void *devid)
>  	return ret0 | ret2;
>  }
>  
> -#ifdef	CONFIG_PM
> -static void pch_dma_save_regs(struct pch_dma *pd)
> +static void __maybe_unused pch_dma_save_regs(struct pch_dma *pd)
>  {
>  	struct pch_dma_chan *pd_chan;
>  	struct dma_chan *chan, *_c;
> @@ -759,7 +758,7 @@ static void pch_dma_save_regs(struct pch_dma *pd)
>  	}
>  }
>  
> -static void pch_dma_restore_regs(struct pch_dma *pd)
> +static void __maybe_unused pch_dma_restore_regs(struct pch_dma *pd)
>  {
>  	struct pch_dma_chan *pd_chan;
>  	struct dma_chan *chan, *_c;
> @@ -782,40 +781,25 @@ static void pch_dma_restore_regs(struct pch_dma *pd)
>  	}
>  }
>  
> -static int pch_dma_suspend(struct pci_dev *pdev, pm_message_t state)
> +static int __maybe_unused pch_dma_suspend(struct device *dev)
>  {
> -	struct pch_dma *pd = pci_get_drvdata(pdev);
> +	struct pch_dma *pd = dev_get_drvdata(dev);
>  
>  	if (pd)
>  		pch_dma_save_regs(pd);
>  
> -	pci_save_state(pdev);
> -	pci_disable_device(pdev);
> -	pci_set_power_state(pdev, pci_choose_state(pdev, state));
> -
>  	return 0;
>  }
>  
> -static int pch_dma_resume(struct pci_dev *pdev)
> +static int __maybe_unused pch_dma_resume(struct device *dev)
>  {
> -	struct pch_dma *pd = pci_get_drvdata(pdev);
> -	int err;
> -
> -	pci_set_power_state(pdev, PCI_D0);
> -	pci_restore_state(pdev);
> -
> -	err = pci_enable_device(pdev);
> -	if (err) {
> -		dev_dbg(&pdev->dev, "failed to enable device\n");
> -		return err;
> -	}
> +	struct pch_dma *pd = dev_get_drvdata(dev);
>  
>  	if (pd)
>  		pch_dma_restore_regs(pd);
>  
>  	return 0;
>  }
> -#endif
>  
>  static int pch_dma_probe(struct pci_dev *pdev,
>  				   const struct pci_device_id *id)
> @@ -993,15 +977,14 @@ static const struct pci_device_id pch_dma_id_table[] = {
>  	{ 0, },
>  };
>  
> +static SIMPLE_DEV_PM_OPS(pch_dma_pm_ops, pch_dma_suspend, pch_dma_resume);
> +
>  static struct pci_driver pch_dma_driver = {
>  	.name		= DRV_NAME,
>  	.id_table	= pch_dma_id_table,
>  	.probe		= pch_dma_probe,
>  	.remove		= pch_dma_remove,
> -#ifdef CONFIG_PM
> -	.suspend	= pch_dma_suspend,
> -	.resume		= pch_dma_resume,
> -#endif
> +	.driver.pm	= &pch_dma_pm_ops,
>  };
>  
>  module_pci_driver(pch_dma_driver);
> -- 
> 2.27.0

-- 
~Vinod