On Fri, May 21, 2010 at 02:44:54PM +0200, Valentin Eduardo (Nokia-D/Helsinki) wrote: > Hello Mike, > > On Fri, Apr 16, 2010 at 11:33:22PM +0200, ext Mike Turquette wrote: > > Introduces voltscale_adaptive_body_bias function to voltage.c. > > voltscale_adaptive_body_bias is called by omap_voltage_scale after a > > voltage transition has occured. Currently voltscale_adaptive_body_bias > > only implements Forward Body-Bias (FBB) for OMAP3630 when MPU runs at > > 1GHz or higher. In the future Reverse Body-Bias might be included. > > > > FBB is an Adaptive Body-Bias technique to boost performance for weak > > process devices at high OPPs. This results in voltage boost on the VDD1 > > PMOS back gates when running at maximum OPP. Current recommendations > > are to enable FBB on all 3630 regardless of silicon characteristics and > > EFUSE values. > > > > ABB applies to all OMAP silicon based on 45nm process, which includes > > OMAP4. OMAP4 recommendations for ABB are not complete and will be added > > to voltscale_adaptive_body_bias in the future. > > > What is not clear to me in this ABB activation is about the idle path. > At least, from your patch, it looks like it does care about ABB & system in > idle state.
I mean, I could NOT find anything regarding idle state handling in your patch. > > So, my question is, what is the recommendation if system idles in 1GHz OPP > with FBB enabled? > Should we care to disable it by software and re-enable it while waking up? > > Or is it somehow bound to SmartReflex activation (then your patch would rely > to the fact that > SR is enabled & disabled before & after WFI)? > > > > > Signed-off-by: Mike Turquette <[email protected]> > > --- > > arch/arm/mach-omap2/voltage.c | 129 > > ++++++++++++++++++++++++++++++++++++++++- > > 1 files changed, 127 insertions(+), 2 deletions(-) > > > > diff --git a/arch/arm/mach-omap2/voltage.c b/arch/arm/mach-omap2/voltage.c > > index c2c8192..98d8bb3 100644 > > --- a/arch/arm/mach-omap2/voltage.c > > +++ b/arch/arm/mach-omap2/voltage.c > > @@ -37,6 +37,11 @@ > > #define VP_IDLE_TIMEOUT 200 > > #define VP_TRANXDONE_TIMEOUT 300 > > > > +#define ABB_MAX_SETTLING_TIME 30 > > +#define ABB_FAST_OPP 1 > > +#define ABB_NOMINAL_OPP 2 > > +#define ABB_SLOW_OPP 3 > > + > > /** > > * OMAP3 Voltage controller SR parameters. TODO: Pass this info as part of > > * board data or PMIC data > > @@ -635,6 +640,118 @@ static int vp_forceupdate_scale_voltage(u32 vdd, > > unsigned long target_volt, > > } > > > > /** > > + * voltscale_adaptive_body_bias - controls ABB ldo during voltage scaling > > + * @target_volt: target voltage determines if ABB ldo is active or bypassed > > + * > > + * Adaptive Body-Bias is a technique in all OMAP silicon that uses the 45nm > > + * process. ABB can boost voltage in high OPPs for silicon with weak > > + * characteristics (forward Body-Bias) as well as lower voltage in low OPPs > > + * for silicon with strong characteristics (Reverse Body-Bias). > > + * > > + * Only Foward Body-Bias for operating at high OPPs is implemented below, > > per > > + * recommendations from silicon team. > > + * Reverse Body-Bias for saving power in active cases and sleep cases is > > not > > + * yet implemented. > > + * OMAP4 hardward also supports ABB ldo, but no recommendations have been > > made > > + * to implement it yet. > > + */ > > +int voltscale_adaptive_body_bias(unsigned long target_volt) > > +{ > > + u32 sr2en_enabled; > > + int timeout; > > + int sr2_wtcnt_value; > > + > > + /* calculate SR2_WTCNT_VALUE settling time */ > > + sr2_wtcnt_value = (ABB_MAX_SETTLING_TIME * > > + (clk_get_rate("sys_ck") / 1000000) / 8); > > + > > + /* has SR2EN been enabled previously? */ > > + sr2en_enabled = (prm_read_mod_reg(OMAP3430_GR_MOD, > > + OMAP3_PRM_LDO_ABB_CTRL_OFFSET) & > > + OMAP3630_SR2EN); > > + > > + /* select fast, nominal or slow OPP for ABB ldo */ > > + /* FIXME: include OMAP4 once recommendations are complete */ > > + if (cpu_is_omap3630() && (target_volt >= 1350000)) { > > + /* program for fast opp - enable FBB */ > > + prm_rmw_mod_reg_bits(OMAP3630_OPP_SEL_MASK, > > + (ABB_FAST_OPP << OMAP3630_OPP_SEL_SHIFT), > > + OMAP3430_GR_MOD, > > + OMAP3_PRM_LDO_ABB_SETUP_OFFSET); > > + > > + /* enable the ABB ldo if not done already */ > > + if (!sr2en_enabled) > > + prm_set_mod_reg_bits(OMAP3630_SR2EN, > > + OMAP3430_GR_MOD, > > + OMAP3_PRM_LDO_ABB_CTRL_OFFSET); > > + } else if (sr2en_enabled) { > > + /* program for nominal opp - bypass ABB ldo */ > > + prm_rmw_mod_reg_bits(OMAP3630_OPP_SEL_MASK, > > + (ABB_NOMINAL_OPP << OMAP3630_OPP_SEL_SHIFT), > > + OMAP3430_GR_MOD, > > + OMAP3_PRM_LDO_ABB_SETUP_OFFSET); > > + } else { > > + /* nothing to do here yet... might enable RBB here someday */ > > + return 0; > > + } > > + > > + /* set ACTIVE_FBB_SEL for all 45nm silicon */ > > + prm_set_mod_reg_bits(OMAP3630_ACTIVE_FBB_SEL, > > + OMAP3430_GR_MOD, > > + OMAP3_PRM_LDO_ABB_CTRL_OFFSET); > > + > > + /* program settling time of 30us for ABB ldo transition */ > > + prm_rmw_mod_reg_bits(OMAP3630_SR2_WTCNT_VALUE_MASK, > > + (sr2_wtcnt_value << OMAP3630_SR2_WTCNT_VALUE_SHIFT), > > + OMAP3430_GR_MOD, > > + OMAP3_PRM_LDO_ABB_CTRL_OFFSET); > > + > > + /* clear ABB ldo interrupt status */ > > + prm_write_mod_reg(OMAP3630_ABB_LDO_TRANXDONE_ST, > > + OCP_MOD, > > + OMAP2_PRCM_IRQSTATUS_MPU_OFFSET); > > + > > + /* enable ABB LDO OPP change */ > > + prm_set_mod_reg_bits(OMAP3630_OPP_CHANGE, > > + OMAP3430_GR_MOD, > > + OMAP3_PRM_LDO_ABB_SETUP_OFFSET); > > + > > + timeout = 0; > > + > > + /* wait until OPP change completes */ > > + while ((timeout < ABB_MAX_SETTLING_TIME ) && > > + (!(prm_read_mod_reg(OCP_MOD, > > + OMAP2_PRCM_IRQSTATUS_MPU_OFFSET) & > > + OMAP3630_ABB_LDO_TRANXDONE_ST))) { > > + udelay(1); > > + timeout++; > > + } > > + > > + if (timeout == ABB_MAX_SETTLING_TIME) > > + pr_debug("ABB: TRANXDONE timed out waiting for OPP change\n"); > > + > > + timeout = 0; > > + > > + /* Clear all pending TRANXDONE interrupts/status */ > > + while (timeout < ABB_MAX_SETTLING_TIME) { > > + prm_write_mod_reg(OMAP3630_ABB_LDO_TRANXDONE_ST, > > + OCP_MOD, > > + OMAP2_PRCM_IRQSTATUS_MPU_OFFSET); > > + if (!(prm_read_mod_reg(OCP_MOD, > > + OMAP2_PRCM_IRQSTATUS_MPU_OFFSET) > > + & OMAP3630_ABB_LDO_TRANXDONE_ST)) > > + break; > > + > > + udelay(1); > > + timeout++; > > + } > > + if (timeout == ABB_MAX_SETTLING_TIME) > > + pr_debug("ABB: TRANXDONE timed out trying to clear status\n"); > > + > > + return 0; > > +} > > + > > +/** > > * get_curr_vdd1_voltage : Gets the current non-auto-compensated vdd1 > > voltage > > * > > * This is a temporary placeholder for this API. This should ideally belong > > @@ -758,11 +875,19 @@ void omap_voltageprocessor_disable(int vp_id) > > int omap_voltage_scale(int vdd, unsigned long target_volt, > > unsigned long current_volt) > > { > > + int ret; > > + > > if (voltscale_vpforceupdate) > > - return vp_forceupdate_scale_voltage(vdd, target_volt, > > + ret = vp_forceupdate_scale_voltage(vdd, target_volt, > > current_volt); > > else > > - return vc_bypass_scale_voltage(vdd, target_volt, current_volt); > > + ret = vc_bypass_scale_voltage(vdd, target_volt, current_volt); > > + > > + /* FIXME OMAP4 needs ABB too; recommendations not yet complete */ > > + if (ret && (cpu_is_omap3630() && vdd == VDD1)) > > + ret = voltscale_adaptive_body_bias(target_volt); > > + > > + return ret; > > } > > > > /** > > -- > > 1.6.3.2 > > > > -- > > 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
