Messages in this thread Patch in this message | | | From | Soren Brinkmann <> | Subject | [PATCH 06/10] tty: xuartps: Force enable the UART in xuartps_console_write | Date | Thu, 17 Oct 2013 14:08:09 -0700 |
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From: Lars-Peter Clausen <lars@metafoo.de>
It is possible that under certain circumstances xuartps_console_write is entered while the UART disabled. When this happens the code will busy loop in xuartps_console_putchar, since the character is never written and the TXEMPTY flag is never set. The result is a system lockup. This patch force enables the UART for the duration of xuartps_console_write to avoid this.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: John Linn <john.linn@xilinx.com> Signed-off-by: Michal Simek <michal.simek@xilinx.com> Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com> --- Squashed from these original patches: tty: xuartps: Force enable the UART in xuartps_console_write
It is possible that under certain circumstances xuartps_console_write is entered while the UART disabled. When this happens the code will busy loop in xuartps_console_putchar, since the character is never written and the TXEMPTY flag is never set. The result is a system lockup. This patch force enables the UART for the duration of xuartps_console_write to avoid this.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
and
tty: xuartps: Fix bad register write in console_write
The commit: serial: xilinx_uartps: Force enable the UART in xuartps_console_write (sha1: d21aec67c1c782314d20b3d619e76cf8aae593dc) caused a new bug as the write to the control register had the offset and the value to write reversed.
Reported-by: Jason Andrews <jasona@cadence.com> Signed-off-by: John Linn <john.linn@xilinx.com> Signed-off-by: Michal Simek <michal.simek@xilinx.com> --- drivers/tty/serial/xilinx_uartps.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c index 6e8ec6e9d5a2..fdc739b55eb3 100644 --- a/drivers/tty/serial/xilinx_uartps.c +++ b/drivers/tty/serial/xilinx_uartps.c @@ -953,7 +953,7 @@ static void xuartps_console_write(struct console *co, const char *s, { struct uart_port *port = &xuartps_port[co->index]; unsigned long flags; - unsigned int imr; + unsigned int imr, ctrl; int locked = 1; if (oops_in_progress) @@ -965,9 +965,19 @@ static void xuartps_console_write(struct console *co, const char *s, imr = xuartps_readl(XUARTPS_IMR_OFFSET); xuartps_writel(imr, XUARTPS_IDR_OFFSET); + /* + * Make sure that the tx part is enabled. Set the TX enable bit and + * clear the TX disable bit to enable the transmitter. + */ + ctrl = xuartps_readl(XUARTPS_CR_OFFSET); + xuartps_writel((ctrl & ~XUARTPS_CR_TX_DIS) | XUARTPS_CR_TX_EN, + XUARTPS_CR_OFFSET); + uart_console_write(port, s, count, xuartps_console_putchar); xuartps_console_wait_tx(port); + xuartps_writel(ctrl, XUARTPS_CR_OFFSET); + /* restore interrupt state, it seems like there may be a h/w bug * in that the interrupt enable register should not need to be * written based on the data sheet -- 1.8.4.1
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