From bb246681b3ed0967489a7401ad528c1aaa1a4c2e Mon Sep 17 00:00:00 2001 From: Anthony Mallet Date: Fri, 5 May 2017 17:30:16 +0200 Subject: [PATCH] USB: serial: ftdi_sio: fix setting latency for unprivileged users Commit 557aaa7ffab6 ("ft232: support the ASYNC_LOW_LATENCY flag") enables unprivileged users to set the FTDI latency timer, but there was a logic flaw that skipped sending the corresponding USB control message to the device. Specifically, the device latency timer would not be updated until next open, something which was later also inadvertently broken by commit c19db4c9e49a ("USB: ftdi_sio: set device latency timeout at port probe"). A recent commit c6dce2626606 ("USB: serial: ftdi_sio: fix extreme low-latency setting") disabled the low-latency mode by default so we now need this fix to allow unprivileged users to again enable it. Signed-off-by: Anthony Mallet [johan: amend commit message] Fixes: 557aaa7ffab6 ("ft232: support the ASYNC_LOW_LATENCY flag") Fixes: c19db4c9e49a ("USB: ftdi_sio: set device latency timeout at port probe"). Cc: stable # 2.6.31 Signed-off-by: Johan Hovold --- drivers/usb/serial/ftdi_sio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c index d38780fa8788..0e634c11abbf 100644 --- a/drivers/usb/serial/ftdi_sio.c +++ b/drivers/usb/serial/ftdi_sio.c @@ -1527,9 +1527,9 @@ static int set_serial_info(struct tty_struct *tty, (new_serial.flags & ASYNC_FLAGS)); priv->custom_divisor = new_serial.custom_divisor; +check_and_exit: write_latency_timer(port); -check_and_exit: if ((old_priv.flags & ASYNC_SPD_MASK) != (priv->flags & ASYNC_SPD_MASK)) { if ((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI) -- 2.20.1