3.8.13.18 -stable review patch. If anyone has any objections, please let me know.
------------------ From: Colin Leitner <[email protected]> commit c1f15196ac3b541d084dc80a8fbd8a74c6a0bd44 upstream. Genuine FTDI chips support only CS7/8. A previous fix in commit 8704211f65a2 ("USB: ftdi_sio: fixed handling of unsupported CSIZE setting") enforced this limitation and reported it back to userspace. However, certain types of smartcard readers depend on specific driver behaviour that requests 0 data bits (not 5) to change into a different operating mode if CS5 has been set. This patch reenables this behaviour for all FTDI devices. Tagged to be added to stable, because it affects a lot of users of embedded systems which rely on these readers to work properly. Reported-by: Heinrich Siebmanns <[email protected]> Tested-by: Heinrich Siebmanns <[email protected]> Signed-off-by: Colin Leitner <[email protected]> Signed-off-by: Johan Hovold <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> Signed-off-by: Kamal Mostafa <[email protected]> --- drivers/usb/serial/ftdi_sio.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c index ede7f9f..8856967 100644 --- a/drivers/usb/serial/ftdi_sio.c +++ b/drivers/usb/serial/ftdi_sio.c @@ -2181,10 +2181,20 @@ static void ftdi_set_termios(struct tty_struct *tty, } /* - * All FTDI UART chips are limited to CS7/8. We won't pretend to + * All FTDI UART chips are limited to CS7/8. We shouldn't pretend to * support CS5/6 and revert the CSIZE setting instead. + * + * CS5 however is used to control some smartcard readers which abuse + * this limitation to switch modes. Original FTDI chips fall back to + * eight data bits. + * + * TODO: Implement a quirk to only allow this with mentioned + * readers. One I know of (Argolis Smartreader V1) + * returns "USB smartcard server" as iInterface string. + * The vendor didn't bother with a custom VID/PID of + * course. */ - if ((C_CSIZE(tty) != CS8) && (C_CSIZE(tty) != CS7)) { + if (C_CSIZE(tty) == CS6) { dev_warn(ddev, "requested CSIZE setting not supported\n"); termios->c_cflag &= ~CSIZE; @@ -2231,6 +2241,9 @@ no_skip: urb_value |= FTDI_SIO_SET_DATA_PARITY_NONE; } switch (cflag & CSIZE) { + case CS5: + dev_dbg(ddev, "Setting CS5 quirk\n"); + break; case CS7: urb_value |= 7; dev_dbg(ddev, "Setting CS7\n"); -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
