* Tero Kristo <tero.kristo@xxxxxxxxx> [100211 03:48]:
> From: Tero Kristo <tero.kristo@xxxxxxxxx>
>
> This patch contains following improvements:
> - Only RX interrupt will now kick the sleep prevent timer
> - TX fifo status is checked before disabling clocks, this will prevent
> on-going transmission to be cut
> - Smartidle is disabled while entering idle if we have data in the transmit
> buffer because having this enabled would prevent wakeups from the TX
> interrupt and this would cause pauses while sending large blocks of data
> - Sleep prevent timer is changed to use ktime_get() instead of a jiffy timer
> as jiffy timers are not valid within idle loop (tick scheduler is stopped)
> - Added RX ignore timer for ignoring the first character received during
> first millisecond of wakeup, this prevents garbage character to be received
> in low sleep states
Cool, sounds like the way to go. Note that current mainline kernel has
the DEFAULT_TIMEOUT set to 0 because of the lost/corrupt characters.
> --- a/arch/arm/mach-omap2/serial.c
> +++ b/arch/arm/mach-omap2/serial.c
> @@ -36,13 +39,14 @@
> #define UART_OMAP_NO_EMPTY_FIFO_READ_IP_REV 0x52
> #define UART_OMAP_WER 0x17 /* Wake-up enable register */
>
> -#define DEFAULT_TIMEOUT (5 * HZ)
> +#define DEFAULT_TIMEOUT (5LL * NSEC_PER_SEC)
Won't apply to mainline..
> @@ -420,9 +443,9 @@ static void omap_uart_idle_init(struct omap_uart_state *uart)
>
> uart->can_sleep = 0;
> uart->timeout = DEFAULT_TIMEOUT;
> - setup_timer(&uart->timer, omap_uart_idle_timer,
> - (unsigned long) uart);
> - mod_timer(&uart->timer, jiffies + uart->timeout);
> +
> + uart->expire_time = ktime_add_ns(ktime_get(), uart->timeout);
> +
> omap_uart_smart_idle_enable(uart, 0);
>
> if (cpu_is_omap34xx()) {
And the above should probably be:
if (uart->timeout)
uart->expire_time = ktime_add_ns(ktime_get(), uart->timeout);
In order to support zero default timeout. Some other changes
may be necessary too if DEFAULT_TIMEOUT is 0.
Regards,
Tony
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