Re: [PATCH] OMAP3: Serial: Improved sleep logic

[Tony Lindgren <tony@atomide.com>]

* Tero Kristo <tero.kristo@nokia.com> [100202 01:38]:
> From: Tero Kristo <tero.kristo@nokia.com>
> 
> Only RX interrupt will now kick the sleep prevent timer. In addition, TX
> fifo status is checked before disabling clocks, this will prevent occasional
> garbage being printed on serial line. Smartidle is also disabled while
> entering idle if we have data in the transmit buffer, because having this
> enabled will prevent wakeups from the TX interrupt, and this causes
> pauses while sending large blocks of data.

Sounds this is for 2.6.34 merge window and does not contain anything
that needs to be fixed for 2.6.33. 

Regards,

Tony

 
> Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
> ---
>  arch/arm/mach-omap2/serial.c |   19 +++++++++++++++----
>  1 files changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
> index 777e802..e11dfe9 100644
> --- a/arch/arm/mach-omap2/serial.c
> +++ b/arch/arm/mach-omap2/serial.c
> @@ -317,7 +317,8 @@ static void omap_uart_allow_sleep(struct omap_uart_state *uart)
>  	if (!uart->clocked)
>  		return;
>  
> -	omap_uart_smart_idle_enable(uart, 1);
> +	if (serial_read_reg(uart->p, UART_LSR) & UART_LSR_TEMT)
> +		omap_uart_smart_idle_enable(uart, 1);
>  	uart->can_sleep = 1;
>  	del_timer(&uart->timer);
>  }
> @@ -335,7 +336,11 @@ void omap_uart_prepare_idle(int num)
>  
>  	list_for_each_entry(uart, &uart_list, node) {
>  		if (num == uart->num && uart->can_sleep) {
> -			omap_uart_disable_clocks(uart);
> +			if (serial_read_reg(uart->p, UART_LSR) &
> +					UART_LSR_TEMT)
> +				omap_uart_disable_clocks(uart);
> +			else
> +				omap_uart_smart_idle_enable(uart, 0);
>  			return;
>  		}
>  	}
> @@ -407,8 +412,14 @@ int omap_uart_can_sleep(void)
>  static irqreturn_t omap_uart_interrupt(int irq, void *dev_id)
>  {
>  	struct omap_uart_state *uart = dev_id;
> +	u8 lsr;
>  
> -	omap_uart_block_sleep(uart);
> +	lsr = serial_read_reg(uart->p, UART_LSR);
> +	/* Check for receive interrupt */
> +	if (lsr & UART_LSR_DR)
> +		omap_uart_block_sleep(uart);
> +	if (lsr & UART_LSR_TEMT && uart->can_sleep)
> +		omap_uart_smart_idle_enable(uart, 1);
>  
>  	return IRQ_NONE;
>  }
> -- 
> 1.5.4.3
> 
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