[U-Boot] [UBOOT RFC PATCH 02/13] usb: gadget: udc-core: Add minimal udc-core from linux kernel

Lukasz Majewski
2014-08-19T15:38:42Z

Hi Felipe, Kishon

> On Tue, Aug 19, 2014 at 08:48:36PM +0530, Kishon Vijay Abraham I
> wrote:
> > Hi Lukasz,
> >
> > On Tuesday 19 August 2014 02:22 PM, Lukasz Majewski wrote:
> > > Hi Kishon,
> > >
> > >> In order to support multiple USB device controllers in uboot,
> > >> udc-core is needed.
> > >
> > > Is it? In u-boot at best only one UDC is operational at a time.
> >
> > I didn't mean operational at the same time. dra7xx has 4 USB
> > controllers and we should allow the user to use any USB port for
> > DFU.
>
> but from u-boot's perspective, that can (should?) be a build-time
> choice. That user, certainly, won't need more than one port active for
> booting, right ?

This is my point. We are working with the bootloader. Some things here
are set at board configuration and aren't changed afterwards (like
only UDC 0 output is wired out).

The dfu/ums commands give you the ability to specify controller if
you need such option.

>
> > >> udc-core also helps to cleanly link the USB
> > >> peripheral driver with the gadget driver. Hence Ported minimal
> > >> udc-core from linux kernel.
> > >
> > > I'd appreciate the exact SHA for this udc-core.c code. And the SHA
> > > should be from some already released mainline code (like final
> > > 3.16), not any private branch nor linux-next.
> >
> > We can't have the exact udc-core.c from linux kernel as it deals
> > with kernel driver model stuff and vfs which is not needed for
> > kernel. Trying to have the exact same code from kernel complicates
> > it.
>
> what he means is to point to the SHA1 when you originally forked the
> code from kernel. Sure udc-core can't be the same, but you based off
> of a known commit ID frmo the kernel.
>

+1

The best way is to grab original source from mailine kernel, and then
provide patch which adjust it. In this way we have clean trace from
where the code comes.

--
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group