On Sun, Nov 27, 2016 at 2:02 PM, Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx> wrote: > Hello, > > while adding USB support on the Amlogic Meson GXL / GXM SoCs I have > come across something I did not know yet: > dwc3 has an internal USB2 hub (from what I can read in the code there > seem to be multiple USB3 ports supported as well). > When searching the web I did not come across any SoC that uses a > configuration with more than one port enabled. > > On my Amlogic Meson GXM device (consumer device, no development board) > I see the following USB2 PHY register configuration (full register > dump from the kernel that was shipped with the device is attached): > GUSB2PHYCFG(0) = 0x40102500 > GUSB2PHYCFG(1) = 0x40102540 > GUSB2PHYCFG(2) = 0x40102540 > > Then vendor kernel sources (a 3.14 kernel) are adding the resets for > GUSB2PHYCFG([1-3]) in dwc3_core_soft_reset(). > A mainline 4.9+(Meson GXL USB PHY patches + dwc3/xhci-plat DMA patches > from linux-usb) kernel works fine even with just applying the reset to > GUSB2PHYCFG(0). > > That brings up two questions: > 1. I guess it makes sense to adjust the upstream dwc3 to add the > resets for all available USB2 PHYs - is there a specific reason why > the current dwc3 driver does not do that (or is it simply because why > we find on Meson GXL/GXM is very exotic)? > 2. would we also implement this for the USB3 "pipes" as well (without > being able to test this)? > 3. from what I can see in the code we have to adjust dwc3_phy_setup() > and ulpi.c to add support for multiple ports, but how do we detect the > number of USB2 and USB3 ports (is this somewhere encoded in the > DWC3_GHWPARAMS registers)? > > lsusb output is also attached, based on the PHY drivers for which the > patches can be found here: [0] > > > Best Regards, > Martin > > > [0] http://lists.infradead.org/pipermail/linux-amlogic/2016-November/001721.html re-sending due to a typo in Felipe Balbi's email address (sorry for that) -- 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
