linux-kernel - Re: [PATCH v2 4/7] [media] uvcvideo: Enable runtime PM of descendant devices

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Date:	Sat, 04 Apr 2015 15:33:20 +0300
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:	linux-pm@...r.kernel.org,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/7] [media] uvcvideo: Enable runtime PM of descendant devices

Hi Tomeu,

Thank you for the patch.

Could you please CC me on the whole series for v3 ?

On Friday 03 April 2015 14:57:53 Tomeu Vizoso wrote:
> So UVC devices can remain runtime-suspended when the system goes into a
> sleep state, they and all of their descendant devices need to have
> runtime PM enable.
> 
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
> ---
>  drivers/media/usb/uvc/uvc_driver.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/media/usb/uvc/uvc_driver.c
> b/drivers/media/usb/uvc/uvc_driver.c index cf27006..687e5fb 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -1855,6 +1855,15 @@ static int uvc_register_chains(struct uvc_device
> *dev) return 0;
>  }
> 
> +static int uvc_pm_runtime_enable(struct device *dev, void *data)
> +{
> +	pm_runtime_enable(dev);
> +
> +	device_for_each_child(dev, NULL, uvc_pm_runtime_enable);

How many recursion levels do we typically have with uvcvideo ?

> +
> +	return 0;
> +}

The function isn't UVC-specific, how about renaming it to 
pm_runtime_enable_recursive() (or something similar) and moving it to the 
runtime PM core ?

> +
>  /* ------------------------------------------------------------------------
> * USB probe, disconnect, suspend and resume
>   */
> @@ -1959,6 +1968,8 @@ static int uvc_probe(struct usb_interface *intf,
>  			"supported.\n", ret);
>  	}
> 
> +	device_for_each_child(&dev->intf->dev, NULL, uvc_pm_runtime_enable);

You could just call uvc_pm_runtime_enable(&dev->intf->dev, NULL) here.

> +
>  	uvc_trace(UVC_TRACE_PROBE, "UVC device initialized.\n");
>  	usb_enable_autosuspend(udev);
>  	return 0;

-- 
Regards,

Laurent Pinchart

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