>-----Original Message----- >From: [email protected] [mailto:linux-omap- >[email protected]] On Behalf Of ext Vishwanath Sripathy >Sent: 19 January, 2011 06:39 >To: Kristo Tero (Nokia-MS/Tampere); [email protected] >Cc: Paul Walmsley; Kevin Hilman >Subject: RE: [PATCH] OMAP3: CPUIdle: prevent CORE from going off if >doing so would reset an active clockdomain > >Tero, > >> -----Original Message----- >> From: [email protected] [mailto:linux-omap- >> [email protected]] On Behalf Of Tero Kristo >> Sent: Tuesday, January 18, 2011 3:18 PM >> To: [email protected] >> Cc: Paul Walmsley; Kevin Hilman >> Subject: [PATCH] OMAP3: CPUIdle: prevent CORE from going off if doing >> so would reset an active clockdomain >> >> On OMAP3 SoCs, if the CORE powerdomain enters off-mode, many other >> parts of the chip will be reset. If those parts of the chip are busy, >> the reset will disrupt them, causing unpredictable and generally >> undesirable results. >If some parts of the chip are busy, then how can Core domain enter off >state? The necessary condition for Core to enter low power state is that >all the clock domains (including DSS, CAM, IVA, USB, PER etc) should >have >idled. Doesn't it mean that all the modules have idled and asserted >idleack when Core is entering off state?
This can happen e.g. when some powerdomain has entered RET state. We have faced this issue at least with IVA2 because it has its own power management. > >Vishwa >> >> Signed-off-by: Tero Kristo <[email protected]> >> Cc: Paul Walmsley <[email protected]> >> Cc: Kevin Hilman <[email protected]> >> --- >> arch/arm/mach-omap2/cpuidle34xx.c | 40 >> +++++++++++++++++++++++++++++++++++- >> 1 files changed, 38 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm/mach-omap2/cpuidle34xx.c b/arch/arm/mach- >> omap2/cpuidle34xx.c >> index f3e043f..d31b858 100644 >> --- a/arch/arm/mach-omap2/cpuidle34xx.c >> +++ b/arch/arm/mach-omap2/cpuidle34xx.c >> @@ -61,7 +61,7 @@ struct omap3_processor_cx { >> struct omap3_processor_cx >> omap3_power_states[OMAP3_MAX_STATES]; >> struct omap3_processor_cx current_cx_state; >> struct powerdomain *mpu_pd, *core_pd, *per_pd; >> -struct powerdomain *cam_pd; >> +struct powerdomain *cam_pd, *dss_pd, *iva2_pd, *sgx_pd, *usb_pd; >> >> /* >> * The latencies/thresholds for various C states have >> @@ -235,7 +235,7 @@ static int omap3_enter_idle_bm(struct >> cpuidle_device *dev, >> { >> struct cpuidle_state *new_state = next_valid_state(dev, state); >> u32 core_next_state, per_next_state = 0, per_saved_state = 0; >> - u32 cam_state; >> + u32 cam_state, dss_state, iva2_state, sgx_state, usb_state; >> struct omap3_processor_cx *cx; >> int ret; >> >> @@ -256,6 +256,8 @@ static int omap3_enter_idle_bm(struct >> cpuidle_device *dev, >> * its own code. >> */ >> >> + /* XXX Add CORE-active check here */ >> + >> /* >> * Prevent idle completely if CAM is active. >> * CAM does not have wakeup capability in OMAP3. >> @@ -275,6 +277,36 @@ static int omap3_enter_idle_bm(struct >> cpuidle_device *dev, >> (core_next_state > PWRDM_POWER_RET)) >> per_next_state = PWRDM_POWER_RET; >> >> + /* XXX Add prevent-PER-off check here */ >> + >> + /* >> + * If we are attempting CORE off, check if any other >> powerdomains >> + * are at retention or higher. CORE off causes chipwide reset >> which >> + * would reset these domains also. >> + */ >> + if (core_next_state == PWRDM_POWER_OFF) { >> + iva2_state = pwrdm_read_pwrst(iva2_pd); >> + sgx_state = pwrdm_read_pwrst(sgx_pd); >> + usb_state = pwrdm_read_pwrst(usb_pd); >> + dss_state = pwrdm_read_pwrst(dss_pd); >> + >> + if (cam_state > PWRDM_POWER_OFF || >> + dss_state > PWRDM_POWER_OFF || >> + iva2_state > PWRDM_POWER_OFF || >> + per_next_state > PWRDM_POWER_OFF || >> + sgx_state > PWRDM_POWER_OFF || >> + usb_state > PWRDM_POWER_OFF) >> + core_next_state = PWRDM_POWER_RET; >> + } >> + >> + /* Fallback to new target core/mpu state */ >> + while (cx->core_state < core_next_state) { >> + state--; >> + cx = cpuidle_get_statedata(state); >> + } >> + >> + new_state = state; >> + >> /* Are we changing PER target state? */ >> if (per_next_state != per_saved_state) >> pwrdm_set_next_pwrst(per_pd, per_next_state); >> @@ -489,6 +521,10 @@ int __init omap3_idle_init(void) >> core_pd = pwrdm_lookup("core_pwrdm"); >> per_pd = pwrdm_lookup("per_pwrdm"); >> cam_pd = pwrdm_lookup("cam_pwrdm"); >> + dss_pd = pwrdm_lookup("dss_pwrdm"); >> + iva2_pd = pwrdm_lookup("iva2_pwrdm"); >> + sgx_pd = pwrdm_lookup("sgx_pwrdm"); >> + usb_pd = pwrdm_lookup("usbhost_pwrdm"); >> >> omap_init_power_states(); >> cpuidle_register_driver(&omap3_idle_driver); >> -- >> 1.7.1 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-omap" >in >> the body of a message to [email protected] >> 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 [email protected] >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 [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
