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| author | Michael Spang <spang@chromium.org> | 2013-03-27 19:34:25 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-03-28 16:04:19 -0700 |
| commit | 38adbc54cea90e220c9212f961a621b2c6af9ae0 (patch) | |
| tree | a9f87cf017db71038715f15e277d3a6f687a280d /drivers/tty | |
| parent | d09a7308e9887a83abfd3176f4416d4142a265dc (diff) | |
| download | linux-38adbc54cea90e220c9212f961a621b2c6af9ae0.tar.gz linux-38adbc54cea90e220c9212f961a621b2c6af9ae0.tar.bz2 linux-38adbc54cea90e220c9212f961a621b2c6af9ae0.zip | |
serial: samsung: Avoid waiting forever for TX ready
The no_console_suspend option allows the console to write to the UART
during early resume, before the serial port itself is resumed. Such
writes hang indefinitely waiting for TX ready.
This adds a check to the console putchar function to drop characters
instead of hanging if the port hasn't been initialized. That way, we
can use no_console_suspend without risk of hanging.
Signed-off-by: Michael Spang <spang@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/samsung.c | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c index 78d9c55a9f84..7883f11b8c53 100644 --- a/drivers/tty/serial/samsung.c +++ b/drivers/tty/serial/samsung.c @@ -1367,6 +1367,13 @@ s3c24xx_serial_console_txrdy(struct uart_port *port, unsigned int ufcon) return (utrstat & S3C2410_UTRSTAT_TXE) ? 1 : 0; } +static bool +s3c24xx_port_configured(unsigned int ucon) +{ + /* consider the serial port configured if the tx/rx mode set */ + return (ucon & 0xf) != 0; +} + #ifdef CONFIG_CONSOLE_POLL /* * Console polling routines for writing and reading from the uart while @@ -1389,6 +1396,11 @@ static void s3c24xx_serial_put_poll_char(struct uart_port *port, unsigned char c) { unsigned int ufcon = rd_regl(cons_uart, S3C2410_UFCON); + unsigned int ucon = rd_regl(cons_uart, S3C2410_UCON); + + /* not possible to xmit on unconfigured port */ + if (!s3c24xx_port_configured(ucon)) + return; while (!s3c24xx_serial_console_txrdy(port, ufcon)) cpu_relax(); @@ -1401,6 +1413,12 @@ static void s3c24xx_serial_console_putchar(struct uart_port *port, int ch) { unsigned int ufcon = rd_regl(cons_uart, S3C2410_UFCON); + unsigned int ucon = rd_regl(cons_uart, S3C2410_UCON); + + /* not possible to xmit on unconfigured port */ + if (!s3c24xx_port_configured(ucon)) + return; + while (!s3c24xx_serial_console_txrdy(port, ufcon)) barrier(); wr_regb(cons_uart, S3C2410_UTXH, ch); @@ -1433,9 +1451,7 @@ s3c24xx_serial_get_options(struct uart_port *port, int *baud, "registers: ulcon=%08x, ucon=%08x, ubdriv=%08x\n", port, ulcon, ucon, ubrdiv); - if ((ucon & 0xf) != 0) { - /* consider the serial port configured if the tx/rx mode set */ - + if (s3c24xx_port_configured(ucon)) { switch (ulcon & S3C2410_LCON_CSMASK) { case S3C2410_LCON_CS5: *bits = 5; |