USB: clarify USB_DT_USB_SSP_CAP_SIZE(ssac) definition

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USB_DT_USB_SSP_CAP_SIZE(ssac) gives the size of the SSP capability
descriptor. The descriptor consists of 12 bytes plus a array of
SSA entries.

The number of SSA entries is stored in a SSAC value in the first 12 bytes,
The USB3.1 specification 9.6.2.5 defines SSAC as zero based:
"The number of Sublink Speed Attributes = SSAC + 1." This is not
intuitive and has already caused some confusion.

Make a small modifiaction to the USB_DT_USB_SSP_CAP_SIZE(ssac)
definition to make it a bit clearer

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Mathias Nyman 2017-12-19 13:28:30 +02:00 • committed by Greg Kroah-Hartman

parent e142dc1ecc

commit 7c0143153c

1 changed files with 2 additions and 2 deletions

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include/uapi/linux/usb/ch9.h

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