The receive FIFO wakeup latency estimate in the omap-serial driver is three orders of magnitude too small. This effectively prevents the MPU from going to a low-power state when CONFIG_CPU_IDLE=y. This is a major power management regression and masks some other FIFO-related bugs in the driver. Fix by correcting the most egregious problem in the RX wakeup latency estimate. There are several other flaws in the estimator; these will be fixed by a separate patch series intended for 3.4. The difference in low-power states with this patch can be observed via debugfs in pm_debug/count. This estimate does not have any effect when CONFIG_CPU_IDLE=n. Signed-off-by: Paul Walmsley <paul@xxxxxxxxx> Cc: Kevin Hilman <khilman@xxxxxx> Cc: Govindraj.R <govindraj.raja@xxxxxx> Cc: Tomi Valkeinen <tomi.valkeinen@xxxxxx> Cc: Alan Cox <alan@xxxxxxxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxx> --- drivers/tty/serial/omap-serial.c | 3 +-- 1 files changed, 1 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 11fa156..72fa783 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -740,8 +740,7 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios, quot = serial_omap_get_divisor(port, baud); /* calculate wakeup latency constraint */ - up->calc_latency = (1000000 * up->port.fifosize) / - (1000 * baud / 8); + up->calc_latency = (USEC_PER_SEC * up->port.fifosize) / (baud / 8); up->latency = up->calc_latency; schedule_work(&up->qos_work); -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
