From: Soren Brinkmann <soren.brinkmann@xilinx.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.cz>,
Michal Simek <michal.simek@xilinx.com>
Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
Lars-Peter Clausen <lars@metafoo.de>,
John Linn <john.linn@xilinx.com>,
Soren Brinkmann <soren.brinkmann@xilinx.com>
Subject: [PATCH 06/10] tty: xuartps: Force enable the UART in xuartps_console_write
Date: Thu, 17 Oct 2013 14:08:09 -0700 [thread overview]
Message-ID: <1382044093-29905-7-git-send-email-soren.brinkmann@xilinx.com> (raw)
In-Reply-To: <1382044093-29905-1-git-send-email-soren.brinkmann@xilinx.com>
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
next prev parent reply other threads:[~2013-10-17 21:08 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-17 21:08 [PATCH 00/10] tty: xuartps: Update Soren Brinkmann
2013-10-17 21:08 ` [PATCH 01/10] tty: xuartps: Use devm_clk_get() Soren Brinkmann
2013-10-17 21:08 ` [PATCH 02/10] tty: xuartps: Use devm_kzalloc Soren Brinkmann
2013-10-17 21:08 ` [PATCH 03/10] tty: xuartps: Implement BREAK detection, add SYSRQ support Soren Brinkmann
2013-12-02 20:42 ` Peter Hurley
2013-10-17 21:08 ` [PATCH 04/10] tty: xuartps: Add polled mode support for xuartps Soren Brinkmann
2013-10-17 21:08 ` [PATCH 05/10] tty: xuartps: support 64 byte FIFO size Soren Brinkmann
2013-10-17 21:08 ` Soren Brinkmann [this message]
2013-10-17 21:08 ` [PATCH 07/10] tty: xuartps: Updating set_baud_rate() Soren Brinkmann
2013-10-17 21:08 ` [PATCH 08/10] tty: xuartps: Dynamically adjust to input frequency changes Soren Brinkmann
2013-10-17 21:08 ` [PATCH 09/10] tty: xuartps: Implement suspend/resume callbacks Soren Brinkmann
2013-10-17 21:08 ` [PATCH 10/10] tty: xuartps: Update copyright information Soren Brinkmann
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