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ea34925f5b
This patch enhances the HID gadget driver to support dynamic configuration
of the interrupt polling interval (bInterval) via configfs. A new
‘interval’ attribute is exposed under each HID function’s configfs
directory, and any write to it will adjust the poll rate for all endpoints
without requiring a rebuild.
When the attribute has never been written, legacy defaults are preserved:
• Full-Speed (FS) endpoints (IN & OUT) poll every 10 ms
• High-Speed (HS) endpoints (IN & OUT) poll every 4 micro-frames
(~1 ms)
To implement this cleanly:
• Add two new fields to f_hid_opts and f_hidg:
– unsigned char interval
– bool interval_user_set
• Introduce dedicated f_hid_opts_interval_show/store functions.
The store routine parses into an unsigned int, bounds‐checks,
assigns to opts->interval, and sets opts->interval_user_set = true.
• Initialize opts->interval = 4 and opts->interval_user_set = false in
hidg_alloc_inst(), then copy both into the live f_hidg instance in
hidg_alloc().
• In hidg_bind(), set each endpoint’s bInterval based on whether the
user has written the attribute:
– If interval_user_set == false, use FS=10 / HS=4
– If interval_user_set == true, use the user’s value for both FS
& HS
Signed-off-by: Ben Hoff <hoff.benjamin.k@gmail.com>
Link: https://lore.kernel.org/r/20250429182809.811786-1-hoff.benjamin.k@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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