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

[Simon Glass]

+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