On Tue, 10 Jan 2012, Alex,Shi wrote:
>
> We have a PCI USB xhci host controller on a new platform. It have no
> line IRQ definition in BIOS. So the Linux driver refuses to initial this
> controller. But Windows works well for it depending on MSI.
>
> Actually, Linux also can work for MSI. This patch skips the first line
> IRQ checking for our HCD in usb-core pci probe, then try to enable MSI
> firstly. That make this HCD works well under Linux.
>
> Thanks for Sarah's suggestion and review for this patch.
> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
> index 13222d3..6545454 100644
> --- a/drivers/usb/core/hcd.c
> +++ b/drivers/usb/core/hcd.c
> @@ -2466,8 +2466,11 @@ int usb_add_hcd(struct usb_hcd *hcd,
> && device_can_wakeup(&hcd->self.root_hub->dev))
> dev_dbg(hcd->self.controller, "supports USB remote wakeup\n");
>
> - /* enable irqs just before we start the controller */
> - if (usb_hcd_is_primary_hcd(hcd)) {
> + /* enable irqs just before we start the controller. But xhci primary
> + * hcd doesn't need this, since it will do it in driver->start();
There's no need to mention xhci in this comment, since the reasoning is
valid no matter what type of controller you have.
> + */
> + if (usb_hcd_is_primary_hcd(hcd) &&
> + !(hcd->driver->flags & HCD_MSI_FST)) {
> retval = usb_hcd_request_irqs(hcd, irqnum, irqflags);
> if (retval)
> goto err_request_irq;
What happens here if HCD_MSI_FIRST is set in the driver but the
controller uses regular IRQs instead of MSI? You'll skip calling
usb_hcd_request_irqs, and the driver won't work.
Alan Stern
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