From: Arnd Bergmann Date: Mon, 25 Jan 2016 21:54:56 +0000 (+0100) Subject: tty: nozomi: avoid a harmless gcc warning X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=899866934d21292b65884fd68c71efcc8c8a1148;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git 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 Signed-off-by: Willy Tarreau --- 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)) {