netdev - Re: [PATCH][RFC] smsc95xx: enable dynamic autosuspend (RFC)

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Date:	Mon, 10 Dec 2012 14:18:21 +0000
From:	Steve Glendinning <steve@...well.net>
To:	Oliver Neukum <oliver@...kum.org>
Cc:	Steve Glendinning <steve.glendinning@...well.net>,
	netdev <netdev@...r.kernel.org>,
	Ming Lei <ming.lei@...onical.com>, linux-usb@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH][RFC] smsc95xx: enable dynamic autosuspend (RFC)

On 10 December 2012 12:09, Oliver Neukum <oliver@...kum.org> wrote:
> So this is a problem with remote wakeup on older hardware?

Exactly, the older hardware revisions can't reliably do it.

>> Unfortunately we don't know if the connected device supports
>> this feature until we query its ID register at runtime.
>>
>> Suggestions on how best to indicate this capability at runtime
>> instead of compile-time would be appreciated, so we don't have
>> to repeatedly fail if accidentally enabled.  Or maybe this is
>> actually the best way?
>
> If this is a problem with remote wakeup, you should up the
> pm counter (usb_autopm_get_noresume()) in .manage_power
> That was the reason I implemented this is a callback and not as
> a helper in usbnet.

Thanks, so something like this should do the job?

static int smsc95xx_manage_power(struct usbnet *dev, int on)
{
struct smsc95xx_priv *pdata = (struct smsc95xx_priv *)(dev->data[0]);

dev->intf->needs_remote_wakeup = on;

if (pdata->features & FEATURE_AUTOSUSPEND)
return 0;

/* this chip revision doesn't support autosuspend */
netdev_info(dev->net, "hardware doesn't support USB autosuspend\n");

if (on)
usb_autopm_get_interface_no_resume(dev->intf);
else
usb_autopm_put_interface_no_suspend(dev->intf);

return 0;
}
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