• Peter Hurley's avatar
    serial: Fix IGNBRK handling · ef8b9ddc
    Peter Hurley authored
    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: default avatarIvan <athlon_@mail.ru>
    Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    ef8b9ddc
8250_core.c 87.2 KB