Subject: [PATCH 16/16] ARM: omap: disable cpuidle for OMAP3 platforms

From: [email-masked] (Kevin Hilman)
Date: Wed, 08 Feb 2012 15:09:51 -0800

Tony Lindgren <[email-masked]> writes:

> * Russell King - ARM Linux <[email-masked]> [120208 08:10]:
>> Commit 2fd149645eb4 (ARM: OMAP2+: UART: Remove omap_uart_can_sleep and add pm_qos)
>> has caused a regression on OMAP3 platforms.
>> 
>> When the UART is trying to transmit data, if we enter a low power mode,
>> transmission stops, which makes serial on OMAP3 unusable - a 'dmesg'
>> takes five minutes to be output at 115200 baud, at a rate of around a
>> block of 16 characters every couple of seconds.
>> 
>> Unfortunately, the commit above can't be reverted because of many other
>> changes in this area, so this implements a dirty fix by disabling
>> CPU idle in the places the original commit does, irrespective of the
>> UART state.
> ...
>
>> --- a/arch/arm/mach-omap2/pm34xx.c
>> +++ b/arch/arm/mach-omap2/pm34xx.c
>> @@ -421,7 +421,7 @@ static void omap3_pm_idle(void)
>>  	local_irq_disable();
>>  	local_fiq_disable();
>>  
>> -	if (omap_irq_pending() || need_resched())
>> +	if (omap_irq_pending() || need_resched() || 1)
>>  		goto out;
>>  
>>  	trace_power_start(POWER_CSTATE, 1, smp_processor_id());
>
> Argh, this is just too ugly. There has got to be a better fix for the
> -rc series.
>
> Looks like the patches to fix omap-serial.c are queued for v3.4,
> so that won't help.
>
> Kevin, what do you have for the -rc fix here to avoid the if (1)
> hack?

There was confusion with Greg about this serial fixes which were
supposed to be for -rc.

He pulled the original series in to -rc, and reverted them when Paul
updated the series.  Then he decided to queue the updated series for
3.4. :(

I've now asked Greg if he can queue that series for 3.3.

Kevin