Re: [PATCH v2 1/3] usb: chipidea: add controller reset API

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, Nov 14, 2014 at 03:33:44PM +0800, Peter Chen wrote:
> On Thu, Nov 13, 2014 at 09:55:34PM -0600, Felipe Balbi wrote:
> > Hi,
> > 
> > On Fri, Nov 14, 2014 at 08:03:15AM +0800, Peter Chen wrote:
> > > Add controller reset API, it may be used for host/otg driver in future.
> > 
> > you need a better commit log here. How would it be used ? when ? And,
> > more importantly, why ?
> > 
> 
> I will add more information
> 
> > Why would we need to reset the IP outside of ->probe() ?
> > 
> > I don't oppose to the refactoring, but why would we ever need to reset
> > this IP ?
> 
> Usually, we need to below reset controller at below situations:
> - Role switch, host->device and device->host
> - Return from hibernation, which the controller will lost its power,
>   and the content of the register are lost.

resetting is probably not the best solution in either case, though. It
might be the easiest, but not the best. For suspend/resume, you would be
better off saving/restoring contenxt and for role switch, you could just
reprogram the few registers which need to change when role swapping.

-- 
balbi

Attachment: signature.asc
Description: Digital signature


[Index of Archives]     [Linux Media]     [Linux Input]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Old Linux USB Devel Archive]

  Powered by Linux