On Mon, Apr 17, 2017 at 04:20:43PM +0800, Peter Chen wrote:
> According to xHCI spec Figure 30: Interrupt Throttle Flow Diagram
>
> If PCI Message Signaled Interrupts (MSI or MSI-X) are enabled,
> then the assertion of the Interrupt Pending (IP) flag in Figure
> 30
> generates a PCI Dword write. The IP flag is automatically
> cleared
> by the completion of the PCI write.
>
> the MSI enabled HCs don't need to clear interrupt pending bit, but
> hcd->irq = 0 doesn't equal to MSI enabled HCD. At some Dual-role
> controller software designs, it sets hcd->irq as 0 to avoid HCD
> requesting interrupt, and they want to decide when to call usb_hcd_irq
> by software.
ping...
>
> Signed-off-by: Peter Chen <peter.c...@nxp.com>
> ---
> Mathias, I am not very sure if the comments I delete is complete
> useless, plese help to check.
>
> drivers/usb/host/xhci-ring.c | 5 +----
> drivers/usb/host/xhci.c | 5 +++--
> include/linux/usb/hcd.h | 1 +
> 3 files changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index d9936c7..f5adbb3 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -2642,12 +2642,9 @@ irqreturn_t xhci_irq(struct usb_hcd *hcd)
> */
> status |= STS_EINT;
> writel(status, &xhci->op_regs->status);
> - /* FIXME when MSI-X is supported and there are multiple vectors */
> - /* Clear the MSI-X event interrupt status */
>
> - if (hcd->irq) {
> + if (!hcd->msi_enabled) {
> u32 irq_pending;
> - /* Acknowledge the PCI interrupt */
> irq_pending = readl(&xhci->ir_set->irq_pending);
> irq_pending |= IMAN_IP;
> writel(irq_pending, &xhci->ir_set->irq_pending);
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index 1828695..dc81041 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -401,9 +401,10 @@ static int xhci_try_enable_msi(struct usb_hcd *hcd)
> /* fall back to msi*/
> ret = xhci_setup_msi(xhci);
>
> - if (!ret)
> - /* hcd->irq is 0, we have MSI */
> + if (!ret) {
> + hcd->msi_enabled = 1;
> return 0;
> + }
>
> if (!pdev->irq) {
> xhci_err(xhci, "No msi-x/msi found and no IRQ in BIOS\n");
> diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
> index a469999..50398b6 100644
> --- a/include/linux/usb/hcd.h
> +++ b/include/linux/usb/hcd.h
> @@ -148,6 +148,7 @@ struct usb_hcd {
> unsigned rh_registered:1;/* is root hub registered? */
> unsigned rh_pollable:1; /* may we poll the root hub? */
> unsigned msix_enabled:1; /* driver has MSI-X enabled? */
> + unsigned msi_enabled:1; /* driver has MSI enabled? */
> unsigned remove_phy:1; /* auto-remove USB phy */
>
> /* The next flag is a stopgap, to be removed when all the HCDs
> --
--
Best Regards,
Peter Chen
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