Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=c8c6bfa39d6bd7347f43937c8767ae145b61bcb4
Commit: c8c6bfa39d6bd7347f43937c8767ae145b61bcb4
Parent: 9d778a69370cc1b643b13648df971c83ff5654ef
Author: Russell King <[EMAIL PROTECTED]>
AuthorDate: Mon Feb 4 22:27:52 2008 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue Feb 5 09:44:10 2008 -0800
serial: avoid stalling suspend if serial port won't drain
Some ports seem to be unable to drain their transmitters on shut down.
Such a
problem can occur if the port is programmed for hardware imposed flow
control,
characters are in the FIFO but the CTS signal is inactive.
Normally, this isn't a problem because most places where we wait for the
transmitter to drain have a time-out. However, there is no timeout in the
suspend path.
Give a port 30ms to drain; this is an arbitary value chosen to avoid long
delays if there are many such ports in the system, while giving a reasonable
chance for a single port to drain. Should a port not drain within this
timeout, issue a warning.
Signed-off-by: Russell King <[EMAIL PROTECTED]>
Acked-by: Alan Cox <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
drivers/serial/serial_core.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 2554d2f..304fe32 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1977,6 +1977,7 @@ int uart_suspend_port(struct uart_driver *drv, struct
uart_port *port)
if (state->info && state->info->flags & UIF_INITIALIZED) {
const struct uart_ops *ops = port->ops;
+ int tries;
state->info->flags = (state->info->flags & ~UIF_INITIALIZED)
| UIF_SUSPENDED;
@@ -1990,9 +1991,14 @@ int uart_suspend_port(struct uart_driver *drv, struct
uart_port *port)
/*
* Wait for the transmitter to empty.
*/
- while (!ops->tx_empty(port)) {
+ for (tries = 3; !ops->tx_empty(port) && tries; tries--) {
msleep(10);
}
+ if (!tries)
+ printk(KERN_ERR "%s%s%s%d: Unable to drain
transmitter\n",
+ port->dev ? port->dev->bus_id : "",
+ port->dev ? ": " : "",
+ drv->dev_name, port->line);
ops->shutdown(port);
}
-
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