>-----Original Message-----
>From: ext Kevin Hilman [mailto:[email protected]]
>Sent: 13 August, 2009 17:17
>To: Kristo Tero (Nokia-D/Tampere)
>Cc: [email protected]
>Subject: Re: [PATCH] PM OMAP3: Change omap3_save_secure_ram to
>be called only during init
>
>Tero Kristo <[email protected]> writes:
>
>> This function is now called only once during the
>initialization of the device
>> and consequent sleep cycles will re-use the same saved
>contents for secure
>> RAM. Users who need secure services should do secure RAM
>saving before
>> entering off-mode, if a secure service has been accessed
>after last save.
>>
>> Signed-off-by: Tero Kristo <[email protected]>
>
>You explain what you're doing, but you don't explain why.
>
>Is there a large latency involved in this save/restore that you're
>trying to eliminate for the no-secure-services case?
There are both latency and reliability issues. The context save uses a hardware
resource which takes an order of hundreds of milliseconds to initialize after a
wake up from off-mode, and also there is no way of checking whether it is ready
from kernel side or not. It just crashes if you use it too quickly.
>
>Kevin
>
>> ---
>> arch/arm/mach-omap2/pm34xx.c | 19 ++++++++++++++++++-
>> 1 files changed, 18 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/arm/mach-omap2/pm34xx.c
>b/arch/arm/mach-omap2/pm34xx.c
>> index 4223622..b8cf5f2 100644
>> --- a/arch/arm/mach-omap2/pm34xx.c
>> +++ b/arch/arm/mach-omap2/pm34xx.c
>> @@ -127,6 +127,12 @@ static void omap3_core_restore_context(void)
>> omap_dma_global_context_restore();
>> }
>>
>> +/*
>> + * FIXME: This function should be called before entering
>off-mode after
>> + * OMAP3 secure services have been accessed. Currently it
>is only called
>> + * once during boot sequence, but this works as we are not
>using secure
>> + * services.
>> + */
>> static void omap3_save_secure_ram_context(u32 target_mpu_state)
>> {
>> u32 ret;
>> @@ -349,7 +355,6 @@ void omap_sram_idle(void)
>> OMAP3_PRM_VOLTCTRL_OFFSET);
>> omap3_core_save_context();
>> omap3_prcm_save_context();
>> - omap3_save_secure_ram_context(mpu_next_state);
>> }
>> /* Enable IO-PAD wakeup */
>> prm_set_mod_reg_bits(OMAP3430_EN_IO, WKUP_MOD, PM_WKEN);
>> @@ -923,6 +928,18 @@ int __init omap3_pm_init(void)
>> }
>> omap3_save_scratchpad_contents();
>>
>> + if (omap_type() != OMAP2_DEVICE_TYPE_GP) {
>> + local_irq_disable();
>> + local_fiq_disable();
>> +
>> + omap_dma_global_context_save();
>> + omap3_save_secure_ram_context(PWRDM_POWER_ON);
>> + omap_dma_global_context_restore();
>> +
>> + local_irq_enable();
>> + local_fiq_enable();
>> + }
>> +
>> err1:
>> return ret;
>> err2:
>> --
>> 1.5.4.3
>>
>> --
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