>-----Original Message----- >From: ext Kevin Hilman [mailto:khilman@xxxxxxxxxxxxxxxxxxx] >Sent: 20 October, 2009 20:48 >To: Kristo Tero (Nokia-D/Tampere) >Cc: linux-omap@xxxxxxxxxxxxxxx >Subject: Re: [PATCH 16/17] OMAP3: PM: Write voltage and clock >setup times dynamically in idle loop > >Tero Kristo <tero.kristo@xxxxxxxxx> writes: > >> From: Tero Kristo <tero.kristo@xxxxxxxxx> >> >> It is suggested by TI (SWPA152 February 2009) to write clksetup, >> voltsetup_time1, voltsetup_time2, voltsetup2 dynamically in >idle loop. > >Can you summarize the reasons why? Basically this optimizes the clksetup / voltsetup times according to the sleep mode. Currently the settings are too high in both retention and off-mode, because the hardware appears to use for example VOLTSETUP2 even if we are not in off-mode, adding extra delay to wakeup. Also, CLKSETUP is too high for retention mode because oscillator is not actually shut-off here. However, now that I think about it, it might be better to change this in a way that it is user configurable whether we want to change the settings or not, maybe add new items in to the prm_setup struct for alternate settings for ret / off and only use these if available. Some boards might actually switch oscillator off in retention mode which would require higher setup time. > >> Signed-off-by: Jouni Hogander <jouni.hogander@xxxxxxxxx> >> --- >> arch/arm/mach-omap2/pm34xx.c | 36 >+++++++++++++++++++++++++----------- >> 1 files changed, 25 insertions(+), 11 deletions(-) >> >> diff --git a/arch/arm/mach-omap2/pm34xx.c >b/arch/arm/mach-omap2/pm34xx.c >> index f492142..ae83121 100644 >> --- a/arch/arm/mach-omap2/pm34xx.c >> +++ b/arch/arm/mach-omap2/pm34xx.c >> @@ -575,6 +575,30 @@ void omap_sram_idle(void) >> if (regset_save_on_suspend) >> pm_dbg_regset_save(1); >> >> + /* Write voltage setup times which are changed dynamically */ > >AFAICT, we only set these values at init time and they are never >changed. Are there some forthcoming patches that change these >dynamically? Following bit of the code actually changes them dynamically, you can see that e.g. CLKSETUP time is either prm_setup.clksetup or 0x1 depending on the sleep mode. But as previously said, I think these should probably be added as new items to the prm_setup struct. > >Kevin > >> + if (core_next_state == PWRDM_POWER_OFF) { >> + prm_write_mod_reg(0, OMAP3430_GR_MOD, >> + OMAP3_PRM_VOLTSETUP1_OFFSET); >> + prm_write_mod_reg(prm_setup.voltsetup2, OMAP3430_GR_MOD, >> + OMAP3_PRM_VOLTSETUP2_OFFSET); >> + prm_write_mod_reg(prm_setup.clksetup, OMAP3430_GR_MOD, >> + OMAP3_PRM_CLKSETUP_OFFSET); >> + } else { >> + prm_write_mod_reg((prm_setup.voltsetup_time2 << >> + OMAP3430_SETUP_TIME2_SHIFT) | >> + (prm_setup.voltsetup_time1 << >> + OMAP3430_SETUP_TIME1_SHIFT), >> + OMAP3430_GR_MOD, >OMAP3_PRM_VOLTSETUP1_OFFSET); >> + prm_write_mod_reg(0, OMAP3430_GR_MOD, >> + OMAP3_PRM_VOLTSETUP2_OFFSET); >> + /* >> + * Use static 1 as only HF_CLKOUT is turned off. >> + * Value taken from application note SWPA152 >> + */ >> + prm_write_mod_reg(0x1, OMAP3430_GR_MOD, >> + OMAP3_PRM_CLKSETUP_OFFSET); >> + } >> + >> /* >> * omap3_arm_context is the location where ARM registers >> * get saved. The restore path then reads from this >> @@ -1379,19 +1403,9 @@ static void __init configure_vc(void) >> OMAP3430_GR_MOD, >> OMAP3_PRM_VC_I2C_CFG_OFFSET); >> >> - /* Write setup times */ >> - prm_write_mod_reg(prm_setup.clksetup, OMAP3430_GR_MOD, >> - OMAP3_PRM_CLKSETUP_OFFSET); >> - prm_write_mod_reg((prm_setup.voltsetup_time2 << >> - OMAP3430_SETUP_TIME2_SHIFT) | >> - (prm_setup.voltsetup_time1 << >> - OMAP3430_SETUP_TIME1_SHIFT), >> - OMAP3430_GR_MOD, OMAP3_PRM_VOLTSETUP1_OFFSET); >> - >> + /* Write static setup times */ >> prm_write_mod_reg(prm_setup.voltoffset, OMAP3430_GR_MOD, >> OMAP3_PRM_VOLTOFFSET_OFFSET); >> - prm_write_mod_reg(prm_setup.voltsetup2, OMAP3430_GR_MOD, >> - OMAP3_PRM_VOLTSETUP2_OFFSET); >> >> pm_dbg_regset_init(1); >> pm_dbg_regset_init(2); >> -- >> 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
