On Wed, 5 Oct 2011, Sarah Sharp wrote:
> To add USB 3.0 link power management (LPM), we need to know what the U1
> and U2 exit latencies are for the xHCI host controller. External USB 3.0
> hubs report these values through the SuperSpeed Capabilities descriptor in
> the BOS descriptor. Make the USB 3.0 roothub for the xHCI host behave
> like an external hub and return the BOS descriptors.
>
> The U1 and U2 exit latencies will vary across each host controller, so we
> need to dynamically fill those values in by reading the exit latencies out
> of the xHC registers. Make the roothub code in the USB core handle
> hub_control() returning the length of the data copied.
>
> Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
> ---
>
> Like so?
Yes, with just a few alterations...
> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
> index 73cbbd8..8b66a4f 100644
> --- a/drivers/usb/core/hcd.c
> +++ b/drivers/usb/core/hcd.c
> @@ -442,7 +442,7 @@ static int rh_call_control (struct usb_hcd *hcd, struct urb *urb)
> struct usb_ctrlrequest *cmd;
> u16 typeReq, wValue, wIndex, wLength;
> u8 *ubuf = urb->transfer_buffer;
> - u8 tbuf [sizeof (struct usb_hub_descriptor)]
> + u8 tbuf [USB_DT_BOS_SIZE + USB_DT_USB_SS_CAP_SIZE]
Get rid of the space before the '['. Dave Brownell used to like having
a space before his opening brackets and parens, but it's not the
standard kernel style.
Also, it would be a good idea to add a comment about the array size.
The array needs to be big enough to hold the BOS descriptor + the SS
Device Capability descriptor, as well as big enough to hold a
usb_hub_descriptor. As it happens, both come out to 15 bytes. But if
things change in the future, people will need to know what's going on.
> --- a/drivers/usb/host/xhci-hub.c
> +++ b/drivers/usb/host/xhci-hub.c
> @@ -28,6 +28,25 @@
> #define PORT_RWC_BITS (PORT_CSC | PORT_PEC | PORT_WRC | PORT_OCC | \
> PORT_RC | PORT_PLC | PORT_PE)
>
> +/* usb 1.1 root hub device descriptor */
> +static u8 usb_bos_descriptor [] = {
> + USB_DT_BOS_SIZE, /* __u8 bLength */
> + USB_DT_BOS, /* __u8 bDescriptorType */
> + 0x0F, 0x00, /* __le16 wTotalLength, 15 bytes */
> + 0x1, /* __u8 bNumDeviceCaps */
> + /* First device capability */
> + USB_DT_USB_SS_CAP_SIZE, /* __u8 bLength, 10 bytes */
> + 0x10, /* Device Capability; value = 16 */
This should be USB_DT_DEVICE_CAPABILITY.
> + USB_SS_CAP_TYPE, /* bDevCapabilityType, SUPERSPEED_USB */
> + 0x00, /* bmAttributes, LTM off by default */
> + USB_5GBPS_OPERATION, 0x00, /* wSpeedsSupported, 5Gbps only */
> + 0x03, /* bFunctionalitySupport,
> + USB 3.0 speed only */
> + 0x00, /* bU1DevExitLat, set later. */
> + 0x00, 0x00 /* __le16 bU2DevExitLat, set later. */
> +};
> +
> +
> static void xhci_common_hub_descriptor(struct xhci_hcd *xhci,
> struct usb_hub_descriptor *desc, int ports)
> {
> @@ -455,6 +474,20 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
> xhci_hub_descriptor(hcd, xhci,
> (struct usb_hub_descriptor *) buf);
> break;
> + case DeviceRequest | USB_REQ_GET_DESCRIPTOR:
> + if ((wValue & 0xff00) != (USB_DT_BOS << 8))
> + goto error;
> +
> + if (hcd->speed != HCD_USB3)
> + goto error;
> +
> + memcpy(buf, &usb_bos_descriptor, sizeof(usb_bos_descriptor));
> + temp = xhci_readl(xhci, &xhci->cap_regs->hcs_params3);
> + buf[12] = HCS_U1_LATENCY(temp);
> + put_unaligned_le16(HCS_U2_LATENCY(temp), &buf[13]);
> +
> + spin_unlock_irqrestore(&xhci->lock, flags);
> + return sizeof(usb_bos_descriptor);
This should return USB_DT_BOS_SIZE + USB_DT_USB_SS_CAP_SIZE.
Alan Stern
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