[PATCH] ARM: avoid Cortex-A9 livelock on tight dmb loops

[Tero Kristo]

On 10/04/18 16:41, Tony Lindgren wrote:
> * Russell King <rmk+kernel at armlinux.org.uk> [180410 10:43]:
>> diff --git a/arch/arm/mach-omap2/prm_common.c b/arch/arm/mach-omap2/prm_common.c
>> index 021b5a8b9c0a..d4ddc78b2a0b 100644
>> --- a/arch/arm/mach-omap2/prm_common.c
>> +++ b/arch/arm/mach-omap2/prm_common.c
>> @@ -523,7 +523,7 @@ void omap_prm_reset_system(void)
>>   	prm_ll_data->reset_system();
>>   
>>   	while (1)
>> -		cpu_relax();
>> +		cpu_do_idle();
>>   }
>>   
> 
> Hmm we need to check so the added WFI here does not cause an
> undesired change to a low power state. Adding Tero to Cc also.

Generally it is a bad idea to call arbitrary WFI within OMAP 
architecture, as this triggers a PRCM power transition and will most 
likely cause a hang if not controlled properly.

Has this patch been tested on any platform that supports proper power 
management?

-Tero
--
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki