Re: [PATCH v2] usb: ehci: Only sleep for post-resume handover ifdevices use persist
From: Julius Werner
Date: Thu Apr 25 2013 - 10:57:29 EST
On Thu, Apr 25, 2013 at 7:38 AM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> 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.
Sorry, will fix that.
>> +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.
The limit is 80 (inclusive), right? Without the diff's leading '+' I
count exactly that...
> Aside from these minor issues, the patch is fine. Fix them and you can
> Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
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