HID: introduce proper zeroing of unused bits in output reports

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Some HID devices are looking on the unused bits in the HID reports they
receive. This is violating the specification, but we want to make those
devices work. Well-behaving devices are unaffected, as they don't care
about the unused bits.

If bitsused % 8 is 0 all bits in data[] get used and we don't need to
clear anything. Otherwise (bitsused % 8) bits of the last byte get used.
By shifting 1 for (bitsused % 8) bits and subtracting 1 we create a mask
consisting of (bitsused % 8) ones and remaining zeroes. By ANDing we
clear the upper unused bits.

Signed-off-by: Simon Budig <simon@budig.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

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Simon Budig 2007-03-12 13:52:04 +01:00 • committed by Jiri Kosina

parent a21bd69e15

commit 46386b5870

1 changed files with 5 additions and 0 deletions

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drivers/hid/hid-core.c

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