[U-Boot] U-Boot Rockchip dwc_hcd question for low-speed devices

[Josh Sanford]

Thanks Simon.  I'm having difficulty finding anything by Stefan Bruns
around that time frame, or much of anything recent pertaining to DWC.  (I
only checked the u-boot-denx.git and u-boot-rockchip.git branches.)  Am I
looking in the wrong place?

On Sat, Dec 19, 2015 at 3:30 PM, Simon Glass <sjg at chromium.org> wrote:

> +Marek, Stephen
>
> Hi Josh,
>
> On 18 December 2015 at 06:26, Josh Sanford <joshs6502 at gmail.com> wrote:
> > All,
> >
> > I am trying to use USB within U-Boot on a Firefly RK3288 (Rockchip)
> board,
> > and I am able to enumerate high-speed devices, but not full-speed or
> > low-speed devices.  I know that the devices are functional, because they
> > work on the same physical hardware when I boot into Linux.  Note that I'm
> > using "U-Boot 2014.10-RK3288-02".
> >
> > As an aside, the built-in "USB 2.0 Hub [MTT]" hub never generates a
> > USB_PORT_STAT_C_CONNECTION for me, even though USB_PORT_STAT_CONNECTION
> goes
> > high immediately after powering on, so I forcibly assert
> > USB_PORT_STAT_C_CONNECTION to allow the rest of the tree to enumerate.
> >
> > High-speed devices can be nested as deeply as I wish and still show up
> > properly, but I can't get low-speed devices (i.e. a keyboard) to work in
> any
> > hub port, including any of the ports directly on the board.  All
> attempts to
> > read from my low-speed devices return all zeros.  When I dig a little
> > deeper, I find myself in int dwc_wait_for_complete(struct usb_device
> *dev,
> > uint32_t channel_num, uint32_t *hcStat, uint32_t *errCnt) {}.
> >
> > On the second iteration through the goto loop, hcintn.b.chhltd and
> > hcintn.b.xacterr are both asserted, but hcintn.b.ack, hcintn.b.nak, and
> > hcintn.b.nyet are not, and errCnt is only 1, so the code sets *hcStat =
> > HCSTAT_REINIT and returns.
> >
> > I do notice that dwc_hcd.c seems not to have any code to support split
> > transactions (or perhaps I simply haven't seen it yet).  If true, I
> wonder
> > whether this code is actually expected to support full-speed and
> low-speed
> > devices.  Do you have any thoughts on the matter?  I wish I were more of
> a
> > USB expert, but I'm regrettably quite a novice.
>
> I believe the split transaction issue is currently being resolved for
> DWC. See for example Stefan Bruns' series from 13th December. It might
> be worth trying that out.
>
> Regards,
> Simon
>