Re: [PATCH] usb host: Faraday FUSBH200 HCD driver.
From: Alan Stern
Date: Mon Mar 18 2013 - 14:47:23 EST
On Mon, 18 Mar 2013, Felipe Balbi wrote:
> On Mon, Mar 18, 2013 at 10:16:56AM -0400, Alan Stern wrote:
> > > > it would cause copious modification and duplication of ehci hcd
> > > > driver. For example, there is no "configured_flag" register in
> > > > fusbh200 controller, yet, ehci hcd driver accesses "configured_flag"
> > > > in function ehci_run which would cause compile errors. Therefore,
> > > > maybe my first patch which refers to oxu210hp-hcd is a better
> > > > solution?
> > >
> > > why don't you just add a quirk flag to ehci struct so that it knows it
> > > shouldn't access CONFIGFLAG register when that's non-existent ?
> > >
> > > There are only 5 uses of configured_flag in ehci-hcd.c, so it should be
> > > easy to wrap that around a flag check.
> > Two of those uses turn configured_flag on and two of them turn it off.
> > However, one of the uses tests its value (the first one in
> > ehci_resume). How would that be handled if configured_flag doesn't
> > exist?
> perhaps they don't use it because they have a root-hub TT ? In that case
> you assume EHCI *always* owns the port. Would that work ?
The usage in ehci_resume is meant for checking whether power was lost
while the controller was suspended. This probably isn't an issue
during runtime suspend; it's likely to come up only during system
suspend. If Yuan-Hsin's platform doesn't support system suspend then
we don't have to worry about it.
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