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Commit ef8b9ddc authored Jun 16, 2014 by Peter Hurley Committed by Greg Kroah-Hartman Jun 19, 2014

serial: Fix IGNBRK handling



If IGNBRK is set without either BRKINT or PARMRK set, some uart
drivers send a 0x00 byte for BREAK without the TTYBREAK flag to the
line discipline, when it should send either nothing or the TTYBREAK flag
set. This happens because the read_status_mask masks out the BI
condition, which uart_insert_char() then interprets as a normal 0x00 byte.

SUS v3 is clear regarding the meaning of IGNBRK; Section 11.2.2, General
Terminal Interface - Input Modes, states:
  "If IGNBRK is set, a break condition detected on input shall be ignored;
   that is, not put on the input queue and therefore not read by any
   process."

Fix read_status_mask to include the BI bit if IGNBRK is set; the
lsr status retains the BI bit if a BREAK is recv'd, which is
subsequently ignored in uart_insert_char() when masked with the
ignore_status_mask.

Affected drivers:
8250 - all
serial_txx9
mfd
amba-pl010
amba-pl011
atmel_serial
bfin_uart
dz
ip22zilog
max310x
mxs-auart
netx-serial
pnx8xxx_uart
pxa
sb1250-duart
sccnxp
serial_ks8695
sirfsoc_uart
st-asc
vr41xx_siu
zs
sunzilog
fsl_lpuart
sunsab
ucc_uart
bcm63xx_uart
sunsu
efm32-uart
pmac_zilog
mpsc
msm_serial
m32r_sio

Unaffected drivers:
omap-serial
rp2
sa1100
imx
icom

Annotated for fixes:
altera_uart
mcf

Drivers without break detection:
21285
xilinx-uartps
altera_jtaguart
apbuart
arc-uart
clps711x
max3100
uartlite
msm_serial_hs
nwpserial
lantiq
vt8500_serial

Unknown:
samsung
mpc52xx_uart
bfin_sport_uart
cpm_uart/core

Fixes: Bugzilla #71651, '8250_core.c incorrectly handles IGNBRK flag'
Reported-by: Ivan <athlon_@mail.ru>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent a859c8b2

drivers/tty/serial/8250/8250_core.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2357,7 +2357,7 @@ serial8250_do_set_termios(struct uart_port port, struct ktermios termios,
		port->read_status_mask = UART_LSR_OE \| UART_LSR_THRE \| UART_LSR_DR;
		if (termios->c_iflag & INPCK)
		port->read_status_mask \|= UART_LSR_FE \| UART_LSR_PE;
		if (termios->c_iflag & (BRKINT \| PARMRK))
		if (termios->c_iflag & (IGNBRK \| BRKINT \| PARMRK))
		port->read_status_mask \|= UART_LSR_BI;

		/*

drivers/tty/serial/altera_uart.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -185,6 +185,12 @@ static void altera_uart_set_termios(struct uart_port *port,
		uart_update_timeout(port, termios->c_cflag, baud);
		altera_uart_writel(port, baudclk, ALTERA_UART_DIVISOR_REG);
		spin_unlock_irqrestore(&port->lock, flags);

		/*
		* FIXME: port->read_status_mask and port->ignore_status_mask
		* need to be initialized based on termios settings for
		* INPCK, IGNBRK, IGNPAR, PARMRK, BRKINT
		*/
		}

		static void altera_uart_rx_chars(struct altera_uart *pp)

drivers/tty/serial/amba-pl010.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -420,7 +420,7 @@ pl010_set_termios(struct uart_port port, struct ktermios termios,
		uap->port.read_status_mask = UART01x_RSR_OE;
		if (termios->c_iflag & INPCK)
		uap->port.read_status_mask \|= UART01x_RSR_FE \| UART01x_RSR_PE;
		if (termios->c_iflag & (BRKINT \| PARMRK))
		if (termios->c_iflag & (IGNBRK \| BRKINT \| PARMRK))
		uap->port.read_status_mask \|= UART01x_RSR_BE;

		/*

drivers/tty/serial/amba-pl011.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1744,7 +1744,7 @@ pl011_set_termios(struct uart_port port, struct ktermios termios,
		port->read_status_mask = UART011_DR_OE \| 255;
		if (termios->c_iflag & INPCK)
		port->read_status_mask \|= UART011_DR_FE \| UART011_DR_PE;
		if (termios->c_iflag & (BRKINT \| PARMRK))
		if (termios->c_iflag & (IGNBRK \| BRKINT \| PARMRK))
		port->read_status_mask \|= UART011_DR_BE;

		/*

drivers/tty/serial/atmel_serial.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1932,7 +1932,7 @@ static void atmel_set_termios(struct uart_port port, struct ktermios termios,
		port->read_status_mask = ATMEL_US_OVRE;
		if (termios->c_iflag & INPCK)
		port->read_status_mask \|= (ATMEL_US_FRAME \| ATMEL_US_PARE);
		if (termios->c_iflag & (BRKINT \| PARMRK))
		if (termios->c_iflag & (IGNBRK \| BRKINT \| PARMRK))
		port->read_status_mask \|= ATMEL_US_RXBRK;

		if (atmel_use_pdc_rx(port))