From e53e597fd4c4a0b6ae58e57d76a240927fd17eaa Mon Sep 17 00:00:00 2001 From: Timur Tabi Date: Fri, 31 Mar 2017 17:05:02 -0500 Subject: [PATCH] tty: pl011: fix earlycon work-around for QDF2400 erratum 44 The work-around for the Qualcomm Datacenter Technologies QDF2400 erratum 44 sets the "qdf2400_e44_present" global variable if the work-around is needed. However, this check does not happen until after earlycon is initialized, which means the work-around is not used, and the console hangs as soon as it displays one character. Fixes: d8a4995bcea1 ("tty: pl011: Work around QDF2400 E44 stuck BUSY bit") Signed-off-by: Timur Tabi Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/amba-pl011.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 56f92d7348bf..b0a377725d63 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -2452,18 +2452,37 @@ static void pl011_early_write(struct console *con, const char *s, unsigned n) uart_console_write(&dev->port, s, n, pl011_putc); } +/* + * On non-ACPI systems, earlycon is enabled by specifying + * "earlycon=pl011,
" on the kernel command line. + * + * On ACPI ARM64 systems, an "early" console is enabled via the SPCR table, + * by specifying only "earlycon" on the command line. Because it requires + * SPCR, the console starts after ACPI is parsed, which is later than a + * traditional early console. + * + * To get the traditional early console that starts before ACPI is parsed, + * specify the full "earlycon=pl011,
" option. + */ static int __init pl011_early_console_setup(struct earlycon_device *device, const char *opt) { if (!device->port.membase) return -ENODEV; - device->con->write = qdf2400_e44_present ? - qdf2400_e44_early_write : pl011_early_write; + /* On QDF2400 SOCs affected by Erratum 44, the "qdf2400_e44" must + * also be specified, e.g. "earlycon=pl011,
,qdf2400_e44". + */ + if (!strcmp(device->options, "qdf2400_e44")) + device->con->write = qdf2400_e44_early_write; + else + device->con->write = pl011_early_write; + return 0; } OF_EARLYCON_DECLARE(pl011, "arm,pl011", pl011_early_console_setup); OF_EARLYCON_DECLARE(pl011, "arm,sbsa-uart", pl011_early_console_setup); +EARLYCON_DECLARE(qdf2400_e44, pl011_early_console_setup); #else #define AMBA_CONSOLE NULL -- 2.20.1