• Arnd Bergmann's avatar
    tty: nozomi: avoid a harmless gcc warning · 56c3cd09
    Arnd Bergmann authored
    [ Upstream commit a4f642a8 ]
    
    The nozomi wireless data driver has its own helper function to
    transfer data from a FIFO, doing an extra byte swap on big-endian
    architectures, presumably to bring the data back into byte-serial
    order after readw() or readl() perform their implicit byteswap.
    
    This helper function is used in the receive_data() function to
    first read the length into a 32-bit variable, which causes
    a compile-time warning:
    
    drivers/tty/nozomi.c: In function 'receive_data':
    drivers/tty/nozomi.c:857:9: warning: 'size' may be used uninitialized in this function [-Wmaybe-uninitialized]
    
    The problem is that gcc is unsure whether the data was actually
    read or not. We know that it is at this point, so we can replace
    it with a single readl() to shut up that warning.
    
    I am leaving the byteswap in there, to preserve the existing
    behavior, even though this seems fishy: Reading the length of
    the data into a cpu-endian variable should normally not use
    a second byteswap on big-endian systems, unless the hardware
    is aware of the CPU endianess.
    
    There appears to be a lot more confusion about endianess in this
    driver, so it probably has not worked on big-endian systems in
    a long time, if ever, and I have no way to test it. It's well
    possible that this driver has not been used by anyone in a while,
    the last patch that looks like it was tested on the hardware is
    from 2008.
    Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
    56c3cd09
nozomi.c 47.9 KB