[U-Boot] [PATCH 1/6] usb: dwc2: Add support for v3 snpsid value

[Peter Griffin]

Hi Marek,

On Tue, 12 May 2015, Marek Vasut wrote:

> On Tuesday, May 12, 2015 at 03:38:27 PM, Peter Griffin wrote:
> > This has been tested to the extent that I can enumerate
> > a asix usb networking adapter and boot a kernel over usb
> > on the 96boards hikey u-boot port I'm currently doing.
> > 
> > Signed-off-by: Peter Griffin <peter.griffin at linaro.org>
> > ---
> >  drivers/usb/host/dwc2.c | 3 ++-
> >  drivers/usb/host/dwc2.h | 1 +
> >  2 files changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/usb/host/dwc2.c b/drivers/usb/host/dwc2.c
> > index e8142ac..19a6007 100644
> > --- a/drivers/usb/host/dwc2.c
> > +++ b/drivers/usb/host/dwc2.c
> > @@ -1015,7 +1015,8 @@ int usb_lowlevel_init(int index, enum usb_init_type
> > init, void **controller) snpsid = readl(&regs->gsnpsid);
> >  	printf("Core Release: %x.%03x\n", snpsid >> 12 & 0xf, snpsid & 0xfff);
> > 
> > -	if ((snpsid & DWC2_SNPSID_DEVID_MASK) != DWC2_SNPSID_DEVID_VER_2xx) {
> > +	if ((snpsid & DWC2_SNPSID_DEVID_MASK) != DWC2_SNPSID_DEVID_VER_2xx &&
> > +	    (snpsid & DWC2_SNPSID_DEVID_MASK) != DWC2_SNPSID_DEVID_VER_3xx) {
> 
> Isn't this then a DWC3 controller instead ?

No I don't believe so. dwc3 is a usb3 controller with different register set AFAIK.

I believe this piece of code is replicating what the Linux
driver does here: -

http://lxr.free-electrons.com/source/drivers/usb/dwc2/core.c#L2664

Also see here for the various different sub core revisions within 2.xx and 3.xx
which are supported by the dwc2 Linux driver
http://lxr.free-electrons.com/source/drivers/usb/dwc2/core.h#L625.

This also matches up with the available datasheet here
https://github.com/96boards/documentation/blob/master/hikey/
Hi6220V100_Multi-Mode_Application_Processor_Function_Description.pdf on page 219
which states it is a USB2 OTG controller, but near the bottom of the page also
tates: -

"The USB core used in Hi6220 is build from Synopsys IP(3.00a).".

I just checked through the DWC_otg_databook.odf, and these revision numbers also match up
with the "Revision History" changes in the document. So it all ties together.

It is worth highlighting at this point that not bailing here (along with setting up
the appropriate clocks to the IP) was enough for me to get a DWC2 core rev 3.00a 
enumerating a ASIX networking adapter and tftp a kernel into DDR. However there maybe
some other changes required to "fully" support the 3.00a hardware version. There is of
course the problem I mentioned in the cover letter regarding enumerating mass storage
devices which may or may not be related to this.

Although a quick grep of the Linux driver only gets three hits

git grep DWC2_CORE_REV_3_00a
core.h:#define DWC2_CORE_REV_3_00a      0x4f54300a
core_intr.c:            if (hsotg->hw_params.snpsid >= DWC2_CORE_REV_3_00a)
hcd.c:  if (hsotg->hw_params.snpsid >= DWC2_CORE_REV_3_00a) {

Neither of which seem relevant to the mass storage device problem (one adds a delay in
the irq handler, and the other sets a bit when freeing the hcd.

kind regards,

Peter.