[U-Boot] [PATCH v2] sunxi: Avoid any assumption between musb gadget and host but fallback to host

[Paul Kocialkowski <contact@paulk.fr>]

Le samedi 04 avril 2015 ? 15:48 +0200, Hans de Goede a ?crit :
> Hi,
> 
> On 04-04-15 15:42, Paul Kocialkowski wrote:
> > Le dimanche 29 mars 2015 ? 13:18 +0200, Hans de Goede a ?crit :
> >> Hi,
> >>
> >> On 28-03-15 18:26, Paul Kocialkowski wrote:
> >>> musb might be used in gadget mode on sunxi, so we don't want to assume anything
> >>> related to host mode, especially USB keyboard support. Thus, there is no reason
> >>> to keep USB_KEYBOARD always enabled and in Kconfig: it is much better fit to
> >>> enable it in the common sunxi config header, when needed (some devices also have
> >>> no USB support at all).
> >>>
> >>> In case gadget mode is not explicitly enabled, this will fallback to host mode.
> >>>
> >>> Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
> >>
> >> Nack, I'm not going to take any patch which removes config USB_KEYBOARD,
> >> having USB_KEYBOARD always enabled on devices with usb host capability
> >> causes a significant penalty in boot time, and some people may want to turn
> >> it off because of that.
> >
> > Actually, I said I would give up on this, but there are still parts of
> > that patch that I need for USB gadget (not related to USB keyboard).
> >
> > Regarding USB keyboard, the best solution IMO would be to set it
> > disabled by default in board/sunxi/Kconfig (both because of the boot
> > time penality and because it's not relevant when using gadget mode) and
> > have it enabled individually in each configs/*_defconfig that uses USB
> > in host mode.
> 
> We try to offer the best ootb experience with the defconfigs and many
> users will not have serial consoles attached, so we really want
> usb-keyboard by default. Actually we can currently already use
> host mode on ehci and gadget mode on musb and then we still want
> usb-keyboard and that is how I expect the majority of the boards
> to eventually be configured ootb.

I hadn't thought of that, it makes sense.

> The only time when we do not want USB_KEYBOARD is when we've no
> usb hosts at all because that will cause linking errors, this
> should go away once we move over usb to the device model which
> will happen soon.

Of course, the best solution would be to have USB keyboard enabled but
not used at run-time when there is no host available at all.

> I'm happy to take patches you need to enable gadget mode, but I
> do not think it is a good idea to flip the the default and then
> add CONFIG_USB_KEYBOARD=y to pretty much every one of our 55
> defconfig files.

Well, the long way to do it without modifying each board would be to:
* switch USB_EHCI to Kconfig
* switch MUSB_HOST and MUSB_GADGET to Kconfig
* default MUSB_GADGET to n
* default MUSB_HOST to y if !MUSB_GADGET
* default USB_KEYBORAD to y if USB_EHCI || MUSB_HOST

That way, we don't have to change the defconfigs and my problem is
solved. What do you think?

This would also be one more step to eliminating
CONFIG_SYS_EXTRA_OPTIONS, which is not a bad thing.

-- 
Paul Kocialkowski, Replicant developer

Replicant is a fully free Android distribution running on several
devices, a free software mobile operating system putting the emphasis on
freedom and privacy/security.

Website: http://www.replicant.us/
Blog: http://blog.replicant.us/
Wiki/tracker/forums: http://redmine.replicant.us/

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