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SubjectRe: [PATCH v2] xhci: Add quirk to workaround the errata seen on Cavium Thunder-X2 Soc
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On 29.10.2018 18:54, Cherian, George wrote:
> Implement workaround for ThunderX2 Errata-129 (documented in
> CN99XX Known Issues" available at Cavium support site).
> As per ThunderX2errata-129, USB 2 device may come up as USB 1
> if a connection to a USB 1 device is followed by another connection to
> a USB 2 device, the link will come up as USB 1 for the USB 2 device.
>
> Resolution: Reset the PHY after the USB 1 device is disconnected.
> The PHY reset sequence is done using private registers in XHCI register
> space. After the PHY is reset we check for the PLL lock status and retry
> the operation if it fails. From our tests, retrying 4 times is sufficient.
>
> Add a new quirk flag XHCI_RESET_PLL_ON_DISCONNECT to invoke the workaround
> in handle_xhci_port_status().
>
> Signed-off-by: George Cherian <george.cherian@cavium.com>
> ---
> drivers/usb/host/xhci-pci.c | 5 +++++
> drivers/usb/host/xhci-ring.c | 35 ++++++++++++++++++++++++++++++++++-
> drivers/usb/host/xhci.h | 1 +
> 3 files changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
> index 51dd8e0..334c009 100644
> --- a/drivers/usb/host/xhci-pci.c
> +++ b/drivers/usb/host/xhci-pci.c
> @@ -231,6 +231,11 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
> if (pdev->vendor == PCI_VENDOR_ID_TI && pdev->device == 0x8241)
> xhci->quirks |= XHCI_LIMIT_ENDPOINT_INTERVAL_7;
>
> + if ((pdev->vendor == PCI_VENDOR_ID_BROADCOM ||
> + pdev->vendor == PCI_VENDOR_ID_CAVIUM) &&
> + pdev->device == 0x9026)
> + xhci->quirks |= XHCI_RESET_PLL_ON_DISCONNECT;
> +
> if (xhci->quirks & XHCI_RESET_ON_RESUME)
> xhci_dbg_trace(xhci, trace_xhci_dbg_quirks,
> "QUIRK: Resetting on resume");
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index f0a99aa..342dd5ac 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -1517,6 +1517,35 @@ static void handle_device_notification(struct xhci_hcd *xhci,
> usb_wakeup_notification(udev->parent, udev->portnum);
> }
>
> +/*
> + * Quirk hanlder for errata seen on Cavium ThunderX2 processor XHCI
> + * Controller.
> + * As per ThunderX2errata-129 USB 2 device may come up as USB 1
> + * If a connection to a USB 1 device is followed by another connection
> + * to a USB 2 device.
> + *
> + * Reset the PHY after the USB device is disconnected if device speed
> + * is less than HCD_USB3.
> + * Retry the reset sequence max of 4 times checking the PLL lock status.
> + *
> + */
> +static void xhci_handle_tx2_wrapper_reset(struct xhci_hcd *xhci)

Maybe rename this to make it more obvious it's about a quirk.
xhci_cavium_reset_phy_quirk() maybe?

> +{
> + struct usb_hcd *hcd = xhci_to_hcd(xhci);
> + u32 pll_lock_check;
> + u32 retry_count = 4;
> +
> + do {
> + /* Assert PHY reset */
> + writel(0x6F, hcd->regs + 0x1048);
> + udelay(10);
> + /* De-assert the PHY reset */
> + writel(0x7F, hcd->regs + 0x1048);
> + udelay(200);
> + pll_lock_check = readl(hcd->regs + 0x1070);
> + } while (!(pll_lock_check & 0x1) && --retry_count);
> +}
> +
> static void handle_port_status(struct xhci_hcd *xhci,
> union xhci_trb *event)
> {
> @@ -1642,8 +1671,12 @@ static void handle_port_status(struct xhci_hcd *xhci,
> goto cleanup;
> }
>
> - if (hcd->speed < HCD_USB3)
> + if (hcd->speed < HCD_USB3) {
> xhci_test_and_clear_bit(xhci, port, PORT_PLC);
> + if ((portsc & PORT_CSC) && !(portsc & 0x1) &&
> + (xhci->quirks & XHCI_RESET_PLL_ON_DISCONNECT))
> + xhci_handle_tx2_wrapper_reset(xhci);
> + }

Check for the quirk first, this way I can ignore the rest of the code when
debugging other issues, and use PORT_CONNECT instead of 0x1

something like:

if ((xhci->quirks & XHCI_RESET_PLL_ON_DISCONNECT) &&
(portsc & PORT_CSC) && !(portsc & PORT_CONNECT))

Thanks
-Mathias

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