>-----Original Message----- >From: ext Kevin Hilman [mailto:khilman@xxxxxxxxxxxxxxxxxxx] >Sent: 13 August, 2009 17:17 >To: Kristo Tero (Nokia-D/Tampere) >Cc: linux-omap@xxxxxxxxxxxxxxx >Subject: Re: [PATCH] PM OMAP3: Change omap3_save_secure_ram to >be called only during init > >Tero Kristo <tero.kristo@xxxxxxxxx> 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 <tero.kristo@xxxxxxxxx> > >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 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe >linux-omap" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >-- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
