On Tuesday, December 22, 2015 at 01:21:04 AM, Stefan Brüns wrote:
The ifdef'ed Linux kernel code uses the 1 based port number, whereas U-Boot puts a 0 based port number into the register. The reason the 0 based port number apparently works can probably be taken from the USB 2.0 spec:
8.4.2.2 Start-Split Transaction Token ... The host must correctly set the port field for single and multiple TT hub implementations. A single TT hub implementation *may ignore* the port field.
Actually, as far as I understand, a multi TT hub defaults to single TT (bAlternateSetting: 0) until switched via SetInterface, so even "port 42" would work.
The change was verified by hardcoding the port number to a wrong value, SPLIT transactions kept working (although using a DWC2 instead of MUSB). Tested hubs are the RPi onboard SMC9514 and an external "05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB". The former is a multi TT hub, the latter single TT only.
Addendum: Tested on sunxi/MUSB by Hans de Goede
Signed-off-by: Stefan Brüns stefan.bruens@rwth-aachen.de Reviewed-by: Hans de Goede hdegoede@redhat.com Tested-by: Hans de Goede hdegoede@redhat.com
Applied both, thanks!
Best regards, Marek Vasut