From mboxrd@z Thu Jan 1 00:00:00 1970 From: dbaryshkov@gmail.com (Dmitry Eremin-Solenikov) Date: Wed, 22 Jun 2011 18:15:17 +0400 Subject: [PATCH 1/2] gpio-vbus: support disabling D+ pullup on suspend In-Reply-To: <20110622140127.GB27654@legolas.emea.dhcp.ti.com> References: <1308745217-10883-1-git-send-email-dbaryshkov@gmail.com> <20110622132314.GG23598@legolas.emea.dhcp.ti.com> <20110622140127.GB27654@legolas.emea.dhcp.ti.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 6/22/11, Felipe Balbi wrote: > Hi, > > On Wed, Jun 22, 2011 at 05:52:18PM +0400, Dmitry Eremin-Solenikov wrote: >> On 6/22/11, 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. >> >> I've thought about this. Should UDC driver should somehow call into OTG >> layer on suspend? My understanding is that otg_set_suspend isn't the call >> that should be done here, is it true? >> >> My idea was that board can ask for D+ disabling, knowing itself the >> behaviour >> of the platform driver on suspend (e.g. PXA27x does disable UDC on >> suspend, >> but I dunno what effect this will cause on Host PC). > > Host PC will only see the device disconnecting. So, what happens if the > user has mounted file systems when you decide to go into suspend ? What happens if user has mounted filesystems when I decide to pull out the cable? I agree with you generally, but I'd like to hear any suggestions. -- With best wishes Dmitry