Re: [PATCH v3 2/3] usb: xhci: implement device_suspend/device_resume entries

[Lu, Baolu]

On 05/08/2015 03:28 PM, Greg Kroah-Hartman wrote:
> On Fri, May 08, 2015 at 09:23:40AM +0800, Lu, Baolu wrote:
> > On 05/08/2015 04:47 AM, Greg Kroah-Hartman wrote:
> > > On Thu, May 07, 2015 at 10:18:15AM +0800, Lu Baolu wrote:
> > > > This patch implements device_suspend/device_resume entries for xHC driver.
> > > > device_suspend will be called when a USB device is about to suspend. It
> > > > will issue a stop endpoint command for each endpoint in this device. The
> > > > Suspend(SP) bit in the command TRB will set which will give xHC a hint
> > > > about the suspend. device_resume will be called when a USB device is just
> > > > resumed. It will ring doorbells of all endpoint unconditionally. XHC may
> > > > use these suspend/resume hints to optimize its operation.
> > > >
> > > > Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > > > ---
> > > >   drivers/usb/host/xhci-hub.c |  2 +-
> > > >   drivers/usb/host/xhci.c     | 40 ++++++++++++++++++++++++++++++++++++++++
> > > >   drivers/usb/host/xhci.h     | 11 +++++++++++
> > > >   3 files changed, 52 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
> > > > index 0827d7c..a83e82e 100644
> > > > --- a/drivers/usb/host/xhci-hub.c
> > > > +++ b/drivers/usb/host/xhci-hub.c
> > > > @@ -266,7 +266,7 @@ int xhci_find_slot_id_by_port(struct usb_hcd *hcd, struct xhci_hcd *xhci,
> > > >    * to complete.
> > > >    * suspend will set to 1, if suspend bit need to set in command.
> > > >    */
> > > > -static int xhci_stop_device(struct xhci_hcd *xhci, int slot_id, int suspend)
> > > > +int xhci_stop_device(struct xhci_hcd *xhci, int slot_id, int suspend)
> > > >   {
> > > >   	struct xhci_virt_device *virt_dev;
> > > >   	struct xhci_command *cmd;
> > > > diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> > > > index ec8ac16..6b61833 100644
> > > > --- a/drivers/usb/host/xhci.c
> > > > +++ b/drivers/usb/host/xhci.c
> > > > @@ -4680,6 +4680,40 @@ int xhci_disable_usb3_lpm_timeout(struct usb_hcd *hcd,
> > > >   		return ret;
> > > >   	return 0;
> > > >   }
> > > > +
> > > > +/*
> > > > + * xHCI compatible host controller driver expects to be notified prior to
> > > > + * selectively suspending a device. xHCI hcd could optimize the endpoint
> > > > + * cache for power saving purpose. Refer to 4.15.1.1 of xHCI 1.1.
> > > > + */
> > > > +void xhci_device_suspend(struct usb_hcd *hcd,
> > > > +			struct usb_device *udev, pm_message_t msg)
> > > You never use the 'msg' field, so please remove it from the callback.
> > 'msg' could be used in another patch to determine the pm event types:
> > auto-suspend or system suspend. I didn't bring up that patch together
> > with this patch series because 1) that's part of xhci 1.1 features, and
> > 2) it's still not tested yet.
> We don't add "features" to kernel code that is not used when it is
> added.  We can always change function calls later as we do not have a
> stable api at all.

Understand it now. I will remove 'msg' fields in v4 patch series.

> thanks,
>
> greg k-h

Thank you.
Baolu
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