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USB: core: Add eUSB2 descriptor and parsing in USB core

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Add support for the 'eUSB2 Isochronous Endpoint Companion Descriptor'
introduced in the recent USB 2.0 specification 'USB 2.0 Double Isochronous
IN Bandwidth' ECN.

It allows embedded USB2 (eUSB2) devices to report and use higher bandwidths
for isochronous IN transfers in order to support higher camera resolutions
on the lid of laptops and tablets with minimal change to the USB2 protocol.

The motivation for expanding USB 2.0 is further clarified in an additional
Embedded USB2 version 2.0 (eUSB2v2) supplement to the USB 2.0
specification. It points out this is optimized for performance, power and
cost by using the USB 2.0 low-voltage, power efficient PHY and half-duplex
link for the asymmetric camera bandwidth needs, avoiding the costly and
complex full-duplex USB 3.x symmetric link and gigabit receivers.

eUSB2 devices that support the higher isochronous IN bandwidth and the new
descriptor can be identified by their device descriptor bcdUSB value of
0x0220

Co-developed-by: Amardeep Rai <amardeep.rai@intel.com>
Signed-off-by: Amardeep Rai <amardeep.rai@intel.com>
Signed-off-by: Kannappan R <r.kannappan@intel.com>
Co-developed-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20250220141339.1939448-1-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kannappan R
2025-02-20 16:13:39 +02:00
committed by Greg Kroah-Hartman
parent 0a86e49acf
commit c749f058b4
3 changed files with 66 additions and 8 deletions
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include/uapi/linux/usb/ch9.h
+15
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@@ -253,6 +253,9 @@ struct usb_ctrlrequest {
#define USB_DT_BOS 0x0f
#define USB_DT_DEVICE_CAPABILITY 0x10
#define USB_DT_WIRELESS_ENDPOINT_COMP 0x11
/* From the eUSB2 spec */
#define USB_DT_EUSB2_ISOC_ENDPOINT_COMP 0x12
/* From Wireless USB spec */
#define USB_DT_WIRE_ADAPTER 0x21
/* From USB Device Firmware Upgrade Specification, Revision 1.1 */
#define USB_DT_DFU_FUNCTIONAL 0x21
@@ -675,6 +678,18 @@ static inline int usb_endpoint_interrupt_type(
/*-------------------------------------------------------------------------*/
/* USB_DT_EUSB2_ISOC_ENDPOINT_COMP: eUSB2 Isoch Endpoint Companion descriptor */
struct usb_eusb2_isoc_ep_comp_descriptor {
__u8 bLength;
__u8 bDescriptorType;
__le16 wMaxPacketSize;
__le32 dwBytesPerInterval;
} __attribute__ ((packed));
#define USB_DT_EUSB2_ISOC_EP_COMP_SIZE 8
/*-------------------------------------------------------------------------*/
/* USB_DT_SSP_ISOC_ENDPOINT_COMP: SuperSpeedPlus Isochronous Endpoint Companion
* descriptor
*/