linux-kernel - Re: [PATCH v2] usb: ehci: Only sleep for post-resume handover if devices use persist

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Date:	Thu, 25 Apr 2013 10:38:52 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Julius Werner <jwerner@...omium.org>
cc:	linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<linux-usb@...r.kernel.org>,
	Vincent Palatin <vpalatin@...omium.org>,
	Sameer Nanda <snanda@...omium.org>
Subject: Re: [PATCH v2] usb: ehci: Only sleep for post-resume handover if
 devices use persist

On Wed, 24 Apr 2013, Julius Werner wrote:

> The current EHCI code sleeps a flat 110ms in the resume path if there
> was a USB 1.1 device connected to its companion controller during
> suspend, waiting for the device to reappear and reset so that it can be
> handed back to the companion. This is necessary if the device uses
> persist, so that the companion controller can actually see it during its
> own resume path.
> 
> However, if the device doesn't use persist, this is entirely
> unnecessary. We might just as well ignore it and have the normal device
> detection/reset/handoff code handle it asynchronously when it eventually
> shows up. As USB 1.1 devices are almost exclusively HIDs these days (for
> which persist has no value), this can allow distros to shave another
> tenth of a second off their resume time.

The patch description needs to mention the new for_each_usb_device() 
core routine.

> --- a/drivers/usb/host/ehci-hub.c
> +++ b/drivers/usb/host/ehci-hub.c
> @@ -42,6 +42,13 @@ static int ehci_hub_control(
>  	u16		wLength
>  );
>  
> +

Unnecessary blank line added.

> +static int persist_enabled_on_companion(struct usb_device *udev, void *unused)
> +{


> --- a/include/linux/usb.h
> +++ b/include/linux/usb.h
> @@ -719,6 +719,7 @@ const struct usb_device_id *usb_match_id(struct usb_interface *interface,
>  extern int usb_match_one_id(struct usb_interface *interface,
>  			    const struct usb_device_id *id);
>  
> +extern int usb_for_each_dev(void *data, int (*fn)(struct usb_device *, void *));

Line is too long.

Aside from these minor issues, the patch is fine.  Fix them and you can 
add

Acked-by: Alan Stern <stern@...land.harvard.edu>

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