Subject: [PATCHv2 10/19] ARM: OMAP4: PM: Work-around for ROM code BUG of IVAHD/TESLA

From: [email-masked] (Kevin Hilman)
Date: Wed, 16 May 2012 16:07:21 -0700

On 05/16/2012 04:05 PM, Kevin Hilman wrote:
> Tero Kristo<[email-masked]>  writes:
>
>> From: Santosh Shilimkar<[email-masked]>
>>
>> The ROM BUG is when MPU Domain OFF wake up sequence that can compromise
>> IVA and Tesla execution.
>>
>> At wakeup from MPU OFF on HS device only (not GP device), when
>> restoring the Secure RAM, the ROM Code reconfigures the clocks the
>> same way it is done at Cold Reset.
>
> Ouch.
>
>> The IVAHD Clocks and Power Domain settings are:
>> 	IVAHD_CM2 IVAHD_CLKCTRL_MODULE_MODE = DISABLE
>> 	IVAHD_CM2 SL2_CLKCTRL_MODULE_MODE = DISABLE
>> 	IVAHD_CM2 SL2_CLKSTCTRL_CLKTRCTRL = HW_AUTO
>> 	IVAHD_PRM IVAHD_PWRSTCTRL_POWERSTATE = OFF
>> The TESLA Clocks and Power Domain settings are:
>> 	TESLA_CM1 TESLA_CLKCTRL_MODULE_MODE = DISABLE
>> 	TESLA_CM1 TESLA_CLKSTCTRL_CLKTRCTRL = HW_AUTO
>> 	TESLA_PRM TESLA_PWRSTCTRL_POWERSTATE = OFF
>>
>> This patch fixes the low power OFF mode code so that the these
>> registers are saved and restore across MPU OFF state.
>>
>> Also because of this limitation, MPU OFF alone is not targeted without
>> device OFF to avoid IVAHD and TESLA execution impact
>
> I don't see where this restriction is implemented.
>
> And, can this be hooked into cluster PM notifiers.

Especially since this only effects a subset of revisions, installing the 
notifier only on effected revisions also removes any overhead on working 
revisions.

Kevin