Re: [PATCH 09/13] OMAP3: PM: Apply errata i540 before save secure ram

[Kevin Hilman <khilman@deeprootsystems.com>]

Nishanth Menon <nm@ti.com> writes:

> Kevin Hilman had written, on 11/19/2010 11:15 AM, the following:
>> Nishanth Menon <nm@ti.com> writes:
>>
>>> From: Eduardo Valentin <eduardo.valentin@nokia.com>
>>>
>>> We need to disable the autoidle bit from MPU INTC,
>>> otherwise INTC would get stall, and we would never
>>> come out of WFI. This must be done before save secure ram
>>> as well because save secure ram also does WFI.
>>>
>>> This patch is just a addition to the current W/A we have for i540,
>>> in order to cover the WFI inside the save secure ram.
>>
>> This 'in addition' doesn't really make sense to me.  This doesn't add
>> anything to the current workaround, it just changes the order of
>> operations.
>
> yes - the "in addition" part is as follows:
>
> ideally speaking you just need the omap3_intc_prepare_idle just before
> wfi. we "in addition" need to protect the save_secure_ram call as well
> because ROM code's WFI hits the same window of the bug that we do in
> the kernel. I believe the "in addition" was meant to state that we
> have to protect the logic of romcode as well..

OK, then it needs to be rephrased.  It doesn't need to (re)summarize the
i540 workaround, since it's already in the kernel.  You could just state:

The existing workaround for erratum i540 (disable MPU INTC auto-idle)
needs to be done before saving secure RAM since secure-mode call can
also do WFI.

Kevin




>
>>
>> Kevin
>>
>>> Signed-off-by: Eduardo Valentin <eduardo.valentin@nokia.com>
>>> ---
>>>  arch/arm/mach-omap2/pm34xx.c |   10 ++++++++--
>>>  1 files changed, 8 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
>>> index f520b38..c7e2db0 100644
>>> --- a/arch/arm/mach-omap2/pm34xx.c
>>> +++ b/arch/arm/mach-omap2/pm34xx.c
>>> @@ -422,6 +422,14 @@ void omap_sram_idle(void)
>>>  				omap3_per_save_context();
>>>  	}
>>>  +	/*
>>> +	 * We need to disable the autoidle bit from MPU INTC,
>>> +	 * otherwise INTC would get stall, and we would never
>>> +	 * come out of WFI. This is done here because
>>> +	 * save secure ram also does WFI.
>>> +	 */
>>> +	omap3_intc_prepare_idle();
>>> +
>>>  	/* CORE */
>>>  	if (core_next_state < PWRDM_POWER_ON) {
>>>  		omap_uart_prepare_idle(0);
>>> @@ -433,8 +441,6 @@ void omap_sram_idle(void)
>>>  		}
>>>  	}
>>>  -	omap3_intc_prepare_idle();
>>> -
>>>  	/*
>>>  	* On EMU/HS devices ROM code restores a SRDC value
>>>  	* from scratchpad which has automatic self refresh on timeout