linux-kernel - Re: [PATCH] usb: move usb_calc_bus

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Date:	Mon, 22 Feb 2016 08:22:02 -0800
From:	Doug Anderson <dianders@...omium.org>
To:	John Youn <John.Youn@...opsys.com>
Cc:	Alan Stern <stern@...land.harvard.edu>,
	Felipe Balbi <balbi@...nel.org>, Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Heiko Stuebner <heiko@...ech.de>,
	Stefan Wahren <stefan.wahren@...e.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Mathias Nyman <mathias.nyman@...ux.intel.com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: move usb_calc_bus_time into common code

John,

On Fri, Feb 19, 2016 at 6:55 PM, John Youn <John.Youn@...opsys.com> wrote:
> On 2/19/2016 2:48 PM, Doug Anderson wrote:
>> Hi,
>>
>> On Fri, Feb 19, 2016 at 1:52 PM, Alan Stern <stern@...land.harvard.edu> wrote:
>>> On Fri, 19 Feb 2016, Arnd Bergmann wrote:
>>>
>>>> The dwc2 dual-role USB controller driver has started calling
>>>> usb_calc_bus_time, and does so regardless of whether it is
>>>> being built as a host controller or gadget. In case all
>>>
>>> Out of curiosity...  Why does dwc2 need to calculate bus times when it
>>> is in device mode?
>>
>> Hoo boy.  it doesn't.  Nor does it need to properly set the even/odd
>> frame in device mode.
>>
>> Basically dwc2's "core.c" has a whole bunch of stuff in it that's host
>> only and isn't guarded with any #ifdef.  ...yet that file is included
>> in gadget-only builds.  It's a bit of a mess.  Take a gander at all of
>> the "dwc2_hc_xxx" functions sitting in "drivers/usb/dwc2/core.c".
>>
>> Long term that needs to be cleaned up, but such a cleanup is going to
>> be a bit of churn so we'd need to schedule it for a time when not much
>> else is going on (and presumably it should be done by John or in close
>> coordination with him so it can get Acked / landed quickly to avoid
>> conflicts?).  To do this we'd have to figure out why some things are
>> in "core.c" and some in "hcd.c" and if it makes sense to move them all
>> to "hcd.c" or if we need a new "core_hc.c" or something...  All of
>> that design predates me.
>>
>
> Yeah, that stuff has been bugging me for a while. I have a branch that
> started a lot of clean-ups, but it's never been a great time to merge
> it.
>
>> In any case I guess we need a solution for right now, huh?
>>
>> One terribly lame hack would be to just make a dummy no-op
>> "dwc2_hc_set_even_odd_frame()" if host mode is disabled.  That doesn't
>> really fix the root problem of lots of host mode code being compiled
>> in a gadget-only driver.  It also adds an ugly "#ifdef".  ...but it
>> does get around the current compile error.
>>
>>
>> What do folks think?
>>
>
> I think if we can fix it for -next in dwc2 by moving all host code out
> of core then we should do it that way. I'll see if I can revive my
> patches.

It looks like Felipe has dropped my series out of his testing/next to
avoid this issue (thanks Felipe!).  I'm interested in getting this
resolved as soon as possible to get things back in.  Is there anything
you'd like me to do to help?

-Doug