From mboxrd@z Thu Jan 1 00:00:00 1970 From: balbi@ti.com (Felipe Balbi) Date: Wed, 22 Jun 2011 17:32:17 +0300 Subject: [PATCH 1/2] gpio-vbus: support disabling D+ pullup on suspend In-Reply-To: References: <20110622132314.GG23598@legolas.emea.dhcp.ti.com> Message-ID: <20110622143216.GE27654@legolas.emea.dhcp.ti.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On Wed, Jun 22, 2011 at 10:30:18AM -0400, Alan Stern wrote: > On Wed, 22 Jun 2011, Felipe Balbi wrote: > > > Hi, > > > > On Wed, Jun 22, 2011 at 04:20:16PM +0400, Dmitry Eremin-Solenikov wrote: > > > Some platforms would like to disable D+ pullup on suspend, to drain as > > > low power, as possible. E.g. this was requested by mioa701 board > > > maintainers. > > > > I think this makes sense to many platforms, but by doing so, you would > > loose connection to the Host PC, so you need to make sure your device > > isn't been used before you go down this road. > > In fact, something like this is _necessary_ for all UDC/PHY drivers > unless the device can guarantee that it will automatically wake up from > suspend in time to service a USB packet (note that the window for > responding to a packet is only a few microseconds). Otherwise the > device would appear to the host to be unresponsive and broken -- better > to do a clean disconnect. > > If suspending the device while it is in use would cause problems ... > then don't suspend it when it is in use! I second your thoughts, but today we don't have enough infrastructure to communicate between PHY and Link, so a clean solution isn't possible, right ? Should we block this patch due to that ? -- balbi -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 490 bytes Desc: Digital signature URL: