usb: host: ohci-platform: Implement ohci_platform_shutdown

[Alan Stern <stern@rowland.harvard.edu>]

On Fri, 22 Mar 2019, Tony Lindgren wrote:

> If OHCI is runtime suspended, we can currently get an "imprecise
> external abort" on reboot with ohci-platform loaded when PM runtime
> is implemented for the SoC.
> 
> Let's fix this by implementing ohci_platform_shutdown with PM runtime
> calls clocking the hardware before calling hcd->driver->shutdown.
> 
> Fixes: 0aa0b93e7af6 ("usb: host: ohci-platform: Add basic runtime PM support")
> Signed-off-by: Tony Lindgren <tony@atomide.com>
> ---
>  drivers/usb/host/ohci-platform.c | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/host/ohci-platform.c b/drivers/usb/host/ohci-platform.c
> --- a/drivers/usb/host/ohci-platform.c
> +++ b/drivers/usb/host/ohci-platform.c
> @@ -240,6 +240,22 @@ static int ohci_platform_probe(struct platform_device *dev)
>  	return err;
>  }
>  
> +static void ohci_platform_shutdown(struct platform_device *pdev)
> +{
> +	struct usb_hcd *hcd = platform_get_drvdata(pdev);
> +	int err;
> +
> +	err = pm_runtime_get_sync(&pdev->dev);
> +	if (err < 0)
> +		pm_runtime_put_noidle(&pdev->dev);
> +
> +	if (hcd->driver->shutdown)
> +		hcd->driver->shutdown(hcd);
> +
> +	if (!err)
> +		pm_runtime_put_sync(&pdev->dev);
> +}

How about putting these runtime PM additions into
usb_hcd_platform_shutdown instead, so they will apply to all platform
controller drivers?

Also, are you certain you want the pm_runtime_put_sync at the end?  If 
the system is shutting down anyway, why waste time doing an extra 
runtime suspend?

Alan Stern

> +
>  static int ohci_platform_remove(struct platform_device *dev)
>  {
>  	struct usb_hcd *hcd = platform_get_drvdata(dev);
> @@ -326,7 +342,7 @@ static struct platform_driver ohci_platform_driver = {
>  	.id_table	= ohci_platform_table,
>  	.probe		= ohci_platform_probe,
>  	.remove		= ohci_platform_remove,
> -	.shutdown	= usb_hcd_platform_shutdown,
> +	.shutdown	= ohci_platform_shutdown,
>  	.driver		= {
>  		.name	= "ohci-platform",
>  		.pm	= &ohci_platform_pm_ops,
>