Re: [RFC PATCH] USB:XHCI:Modify XHCI driver for USB2.0 controller
From: liulongfang
Date: Fri Feb 26 2021 - 22:35:42 EST
On 2021年2月26日 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.
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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
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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.
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>
>
>
> Signed-off-by: Longfang Liu <liulongfang@xxxxxxxxxx>
>
> ---
>
> drivers/usb/host/xhci-pci.c | 15 ++-------------
>
> 1 file changed, 2 insertions(+), 13 deletions(-)
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>
>
> 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 */
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> -
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> - if (!(xhci->quirks & XHCI_BROKEN_STREAMS) &&
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> - HCC_MAX_PSA(xhci->hcc_params) >= 4)
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> - xhci->shared_hcd->can_do_streams = 1;
>
>
>
> /* USB-2 and USB-3 roothubs initialized, allow runtime pm suspend */
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> 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