lkml.org 
[lkml]   [2015]   [Jan]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH v2 4/4] mfd: dln2: add suspend/resume functionality
    From
    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.


    \
     
     \ /
      Last update: 2015-01-07 14:41    [W:6.447 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site