diff options
| author | Felipe Balbi <felipe.balbi@linux.intel.com> | 2017-12-14 09:50:39 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-12-15 20:45:43 +0100 |
| commit | 886ee36e7205a7b850e2e5c2298a479f581f9b3b (patch) | |
| tree | 0c52649fb1d4fb87550c006c000b8fb1b037da16 /drivers/usb/core/message.c | |
| parent | 66222f0d4b0ffba0bae2a6a785dc6eaa67cf532e (diff) | |
usb: core: add support for USB_REQ_SET_ISOCH_DELAY
USB SS and SSP hubs provide wHubDelay values on their hub descriptor
which we should inform the USB Device about.
The USB Specification 3.0 explains, on section 9.4.11, how to
calculate the value and how to issue the request. Note that a
USB_REQ_SET_ISOCH_DELAY is valid on all device states (Default,
Address, Configured), we just *chose* to issue it from Address state
right after successfully fetching the USB Device Descriptor.
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/core/message.c')
| -rw-r--r-- | drivers/usb/core/message.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c index dac4adeec213..c64cf6c4a83d 100644 --- a/drivers/usb/core/message.c +++ b/drivers/usb/core/message.c @@ -916,6 +916,30 @@ int usb_get_device_descriptor(struct usb_device *dev, unsigned int size) return ret; } +/* + * usb_set_isoch_delay - informs the device of the packet transmit delay + * @dev: the device whose delay is to be informed + * Context: !in_interrupt() + * + * Since this is an optional request, we don't bother if it fails. + */ +int usb_set_isoch_delay(struct usb_device *dev) +{ + /* skip hub devices */ + if (dev->descriptor.bDeviceClass == USB_CLASS_HUB) + return 0; + + /* skip non-SS/non-SSP devices */ + if (dev->speed < USB_SPEED_SUPER) + return 0; + + return usb_control_msg(dev, usb_sndctrlpipe(dev, 0), + USB_REQ_SET_ISOCH_DELAY, + USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE, + cpu_to_le16(dev->hub_delay), 0, NULL, 0, + USB_CTRL_SET_TIMEOUT); +} + /** * usb_get_status - issues a GET_STATUS call * @dev: the device whose status is being checked |