On 2021/2/26 17:22, Mathias Nyman wrote: > On 26.2.2021 10.21, Longfang Liu wrote: >> Our current XHCI hardware controller has been customized to only >> support USB 2.0 ports. When using the current xhci driver, an xhci >> controller device and an ehci controller device will be created >> automatically. We want the driver to create only one ehci controller. >> After modifying the driver as follows, an error will occur. >> Is there any other modification method? > > The xhci driver relies on the existence of both a main and a shared hcd. > One hcd for handing USB 2 (and slower) and the other for USB 3 devices. > > As one example xhci_run(hcd) needs to be called for both hcds, first call > sets up things, second one calls xhci_start() that makes the controller run. > > It's probably possible to modify the driver to support xHCI hosts with only > USB 2 ports, but requires a lot more work. > >> >> Signed-off-by: Longfang Liu <liulongfang@xxxxxxxxxx> >> --- >> drivers/usb/host/xhci-pci.c | 15 ++------------- >> 1 file changed, 2 insertions(+), 13 deletions(-) >> >> diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c >> index ef513c2..7296aad 100644 >> --- a/drivers/usb/host/xhci-pci.c >> +++ b/drivers/usb/host/xhci-pci.c >> @@ -364,26 +364,15 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id) >> /* USB 2.0 roothub is stored in the PCI device now. */ >> hcd = dev_get_drvdata(&dev->dev); >> xhci = hcd_to_xhci(hcd); >> - xhci->shared_hcd = usb_create_shared_hcd(&xhci_pci_hc_driver, &dev->dev, >> - pci_name(dev), hcd); >> - if (!xhci->shared_hcd) { >> - retval = -ENOMEM; >> - goto dealloc_usb2_hcd; >> - } >> - >> + xhci->shared_hcd = NULL; >> retval = xhci_ext_cap_init(xhci); >> if (retval) >> goto put_usb3_hcd; >> >> - retval = usb_add_hcd(xhci->shared_hcd, dev->irq, >> + retval = usb_add_hcd(xhci->main_hcd, dev->irq, >> IRQF_SHARED); >> if (retval) >> goto put_usb3_hcd; >> - /* Roothub already marked as USB 3.0 speed */ >> - >> - if (!(xhci->quirks & XHCI_BROKEN_STREAMS) && >> - HCC_MAX_PSA(xhci->hcc_params) >= 4) >> - xhci->shared_hcd->can_do_streams = 1; >> >> /* USB-2 and USB-3 roothubs initialized, allow runtime pm suspend */ >> pm_runtime_put_noidle(&dev->dev); >> > > Something like the above could of course not be accepted upstream. We can't break existing > functionality to support one modified xHCI. > > Thanks > Mathias > . > Thanks very much. Longfang Liu