Messages in this thread | | | Date | Thu, 8 Jan 2015 02:16:15 +1300 | Subject | Re: [PATCH v2 4/4] mfd: dln2: add suspend/resume functionality | From | Octavian Purdila <> |
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On Wed, Jan 7, 2015 at 11:26 PM, Johan Hovold <johan@kernel.org> wrote: > On Tue, Dec 16, 2014 at 05:57:15PM +0200, Octavian Purdila wrote: >> Without suspend/resume functionality in the USB driver the USB core >> will disconnect and reconnect the DLN2 port and because the GPIO >> framework does not yet support removal of an in-use controller a >> suspend/resume operation will result in a crash. >> >> This patch provides suspend and resume functions for the DLN2 driver >> so that the above scenario is avoided. >> >> Signed-off-by: Octavian Purdila <octavian.purdila@intel.com> > > This patch looks good now, but how did you say this device was powered? > > If powered by vbus you cannot assume that the device maintains it's > state over a suspend cycle, something which would complicate matters > quite a bit... >
Yes, the device is powered by VBUS. During my tests, depending on the host and USB port, VBUS is sometimes preserved - and this is the case this patch addresses, and sometimes is not, but in that case because no reset_resume routine is implemented the resume path will go through the disconnect/reconnect process. This second case is not addressed by the patch, as I think in this second case fixing the GPIO framework to support the removal of an in-use device is the best way to go.
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