@@ -24,6 +24,7 @@
#include <linux/sysrq.h>
#include <linux/delay.h>
#include <linux/mutex.h>
+#include <linux/math64.h>
#include <linux/security.h>
#include <linux/irq.h>
@@ -333,15 +334,18 @@ void
uart_update_timeout(struct uart_port *port, unsigned int cflag,
unsigned int baud)
{
- unsigned int size;
+ unsigned int size = tty_get_frame_size(cflag);
+ u64 frame_time;
- size = tty_get_frame_size(cflag) * port->fifosize;
+ frame_time = (u64)size * NSEC_PER_SEC;
+ size *= port->fifosize;
/*
* Figure the timeout to send the above number of bits.
* Add .02 seconds of slop
*/
port->timeout = (HZ * size) / baud + HZ/50;
+ port->frame_time = DIV64_U64_ROUND_UP(frame_time, baud);
}
EXPORT_SYMBOL(uart_update_timeout);
@@ -1596,10 +1600,8 @@ static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
* Note: we have to use pretty tight timings here to satisfy
* the NIST-PCTS.
*/
- char_time = (port->timeout - HZ/50) / port->fifosize;
- char_time = char_time / 5;
- if (char_time == 0)
- char_time = 1;
+ char_time = max(nsecs_to_jiffies(port->frame_time / 5), 1UL);
+
if (timeout && timeout < char_time)
char_time = timeout;
@@ -232,6 +232,7 @@ struct uart_port {
int hw_stopped; /* sw-assisted CTS flow state */
unsigned int mctrl; /* current modem ctrl settings */
unsigned int timeout; /* character-based timeout */
+ unsigned int frame_time; /* frame timing in ns */
unsigned int type; /* port type */
const struct uart_ops *ops;
unsigned int custom_divisor;
Struct uart_port currently stores FIFO timeout. Having character timing information readily available is useful. Even serial core itself determines char_time from port->timeout using inverse calculation. Store frame_time directly into uart_port. Character time is stored in nanoseconds to have reasonable precision with high rates. To avoid overflow, 64-bit math is necessary. It might be possible to determine timeout from frame_time by multiplying it with fifosize as needed but only part of the users seem to be protected by a lock. Thus, this patch does not pursue storing only frame_time in uart_port. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> --- drivers/tty/serial/serial_core.c | 14 ++++++++------ include/linux/serial_core.h | 1 + 2 files changed, 9 insertions(+), 6 deletions(-)