On Thu, 21 Jan 2016, Doug Anderson wrote: > This doesn't sound familiar to me, but as far as I know all the > official Raspberry Pi kernels use a pretty different dwc2 driver. See > the (non-mainline) code in drivers/usb/host/dwc_otg/ in the Raspberry > Pi tree at <https://github.com/raspberrypi/linux.git>. Ah, thanks for that pointer. I also found the page at raspberrypi.org which describes how to build and install a custom kernel. > The Raspberry Pi driver and the mainline driver are pretty different > (though they have the same heritage). As far as I remember the > Raspberry Pi driver has feature to enable FIQ for helping deal with > some of the dwc2 issues. That gives it a chunk of code that's totally > rewritten... Indeed, dwc_otg is quite different from dwc2. I found what appears to be a bug in the dwc_otg's _hub_info() routine. (This is the subroutine that gets the upstream hub address and port number for devices behind a TT.) It does: *port_addr = urb->dev->tt->multi ? urb->dev->ttport : 1; However, the USB spec says that the SPLIT packet's third byte is supposed to contain the port for both single-TT and multi-TT hubs. And sure enough, the upstream hub for this non-working device is single-TT. Presumably that explains why the third byte in the SPLIT packet was 0x01 rather than 0x04. The corresponding line in the dwc2_host_hub_info() routine simply does: *hub_port = urb->dev->ttport; Unfortunately, even after I changed the dwc_otg routine the device still didn't work. My bus analyzer isn't on hand today, so I'll have to work on it more next week. > It would be really interesting to see if the patch series I just > posted helps you (it fixes lots of problems in the mainline driver > with splits), though it might still not be enough on the Raspberry Pi > since the CPU clock there is much slower than on my 1.8GHz A12-based > system and thus maybe FIQ is a must have there... Can you tell me how to configure a mainline kernel to work on the Raspberry Pi? There is no arch/arm/configs/bcmrpi_defconfig. > Anyway, sorry if that's not terribly helpful. :( John may have more > familiarity with the non-mainline driver (or know people who are more > familiar with it). Thanks, Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
