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| author | Arnd Bergmann <arnd@arndb.de> | 2016-01-25 22:54:56 +0100 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2017-05-09 08:19:43 +0200 |
| commit | 070d8f38c897946759a3e95f3e4e65f9ccd95b25 (patch) | |
| tree | 778358998cf9bf11bf5c8548e1ca87914af0ac0a | |
| parent | 36c65fa1834ed4bc54497a4ffae65058b6c6bb63 (diff) | |
| download | linux-rt-070d8f38c897946759a3e95f3e4e65f9ccd95b25.tar.gz | |
tty: nozomi: avoid a harmless gcc warning
commit a4f642a8a3c2838ad09fe8313d45db46600e1478 upstream.
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: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
| -rw-r--r-- | drivers/tty/nozomi.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/tty/nozomi.c b/drivers/tty/nozomi.c index d6080c3831ef..ce2e5d508fe7 100644 --- a/drivers/tty/nozomi.c +++ b/drivers/tty/nozomi.c @@ -823,7 +823,7 @@ static int receive_data(enum port_type index, struct nozomi *dc) struct tty_struct *tty = tty_port_tty_get(&port->port); int i, ret; - read_mem32((u32 *) &size, addr, 4); + size = __le32_to_cpu(readl(addr)); /* DBG1( "%d bytes port: %d", size, index); */ if (tty && test_bit(TTY_THROTTLED, &tty->flags)) { |