Re: [PATCH 4/4] OMAP: Voltage: Adaptive Body-Bias handlers

["Cousson, Benoit" <b-cousson@ti.com>]

Hi Mike,

On 2/21/2011 8:47 PM, Turquette, Mike wrote:
> On Mon, Feb 21, 2011 at 4:31 AM, Gulati, Shweta<shweta.gulati@ti.com>  wrote:
>> Hi,
>>
>> On Fri, Feb 18, 2011 at 2:50 PM, Mike Turquette<mturquette@ti.com>  wrote:
>>> Introduce voltage transition notification handlers for Adaptive Body-Bias
>>> LDOs.  There is an ABB LDO for VDD_MPU on OMAP3630 and an ABB_LDO on VDD_MPU
>>> and VDD_IVA on OMAP4430.
>>>
>>> All of these LDOs are handled similary.  Initial configuration is to enable
>>> the possibility of going into Forward Body-Bias (which boosts voltage at
>>> high OPPs).  This feature was designed for weak silicon, and eFuse values
>>> exist to control whether or not this feature should be turned on.  However
>>> recommendations from hardware folks always say to leave it on regardless of
>>> eFuse values, so we don't bother checking them.  For all other OPPs the LDO
>>> is in bypass and will follow the voltage of it's corresponding VDD_xxx.
>>> Reverse Body-Bias exists but we never use this in practice (for saving power
>>> on strongly characterised silicon).
>> Would RBB be never enabled in future for any of the OPPs or any platforms
>> that way SLOW_OPP should also be added in OPP types
>
> Will do this in next version.  RBB is a possibility.

You should not waste you time with that, the RBB should be remove from 
the TRM soon.
That mode is not supported anymore.

Benoit

>
>>> Upon a DVFS transition the notifiers handle the sequencing of voltage
>>> scaling and ABB LDO transitions.  When moving to a higher OPP that needs
>>> FBB, raise voltage first and then enable FBB.  When moving down to an OPP
>>> that bypasses ABB, first bypass the LDO then lower voltage.
>>>
>>> Signed-off-by: Mike Turquette<mturquette@ti.com>
>>> ---
>>>   arch/arm/mach-omap2/voltage.c             |  379 ++++++++++++++++++++++++++++-
>>>   arch/arm/plat-omap/include/plat/voltage.h |    6 +-
>>>   2 files changed, 370 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/arch/arm/mach-omap2/voltage.c b/arch/arm/mach-omap2/voltage.c
>>> index 6ede092..644a45f 100644
>>> --- a/arch/arm/mach-omap2/voltage.c
>>> +++ b/arch/arm/mach-omap2/voltage.c
>>> @@ -43,6 +43,16 @@
>>>   #define FAST_OPP               0x1
>>>   #define NOMINAL_OPP            0x0
>>>
>>> +/* prototypes used by ABB function pointers */
>>> +static int omap_abb_notify_voltage(struct notifier_block *nb,
>>> +               unsigned long val, void *data);
>>> +
>>> +static int omap3_abb_configure(struct omap_abb_info *abb);
>>> +static int omap3_abb_set_opp(struct omap_abb_info *abb, int opp_type);
>>> +
>>> +static int omap4_abb_configure(struct omap_abb_info *abb);
>>> +static int omap4_abb_set_opp(struct omap_abb_info *abb, int opp_type);
>>> +
>>>   static struct omap_vdd_info *vdd_info;
>>>   /*
>>>   * Number of scalable voltage domains.
>>> @@ -70,9 +80,11 @@ static struct omap_vdd_info omap3_vdd_info[] = {
>>>                                         = OMAP3_PRM_IRQSTATUS_MPU_OFFSET,
>>>                         .done_st_shift  = OMAP3630_ABB_LDO_TRANXDONE_ST_SHIFT,
>>>                         .done_st_mask   = OMAP3630_ABB_LDO_TRANXDONE_ST_MASK,
>>> -                       .configure      = NULL,
>>> -                       .nb_handler     = NULL,
>>> -                       .set_opp        = NULL,
>>> +                       .nb     = {
>>> +                               .notifier_call = omap_abb_notify_voltage,
>>> +                       },
>>> +                       .configure      = omap3_abb_configure,
>>> +                       .set_opp        = omap3_abb_set_opp,
>>>                 },
>>>         },
>>>         {
>>> @@ -113,9 +125,11 @@ static struct omap_vdd_info omap4_vdd_info[] = {
>>>                                         = OMAP4_PRM_IRQSTATUS_MPU_2_OFFSET,
>>>                         .done_st_shift  = OMAP4430_ABB_MPU_DONE_ST_SHIFT,
>>>                         .done_st_mask   = OMAP4430_ABB_MPU_DONE_ST_MASK,
>>> -                       .configure      = NULL,
>>> -                       .nb_handler     = NULL,
>>> -                       .set_opp        = NULL,
>>> +                       .nb             = {
>>> +                               .notifier_call = omap_abb_notify_voltage,
>>> +                       },
>>> +                       .configure      = omap4_abb_configure,
>>> +                       .set_opp        = omap4_abb_set_opp,
>>>                 },
>>>         },
>>>         {
>>> @@ -137,9 +151,11 @@ static struct omap_vdd_info omap4_vdd_info[] = {
>>>                                         = OMAP4_PRM_IRQSTATUS_MPU_OFFSET,
>>>                         .done_st_shift  = OMAP4430_ABB_IVA_DONE_ST_SHIFT,
>>>                         .done_st_mask   = OMAP4430_ABB_IVA_DONE_ST_MASK,
>>> -                       .configure      = NULL,
>>> -                       .nb_handler     = NULL,
>>> -                       .set_opp        = NULL,
>>> +                       .nb             = {
>>> +                               .notifier_call = omap_abb_notify_voltage,
>>> +                       },
>>> +                       .configure      = omap4_abb_configure,
>>> +                       .set_opp        = omap4_abb_set_opp,
>>>                 },
>>>         },
>>>         {
>>> @@ -194,7 +210,7 @@ static struct omap_volt_data omap36xx_vddmpu_volt_data[] = {
>>>                         NOMINAL_OPP),
>>>         VOLT_DATA_DEFINE(OMAP3630_VDD_MPU_OPP100_UV,
>>>                         OMAP3630_CONTROL_FUSE_OPP100_VDD1, 0xf9, 0x16,
>>> -                       NOMINAL_OPP),
>>> +                       FAST_OPP),
>>>         VOLT_DATA_DEFINE(OMAP3630_VDD_MPU_OPP120_UV,
>>>                         OMAP3630_CONTROL_FUSE_OPP120_VDD1, 0xfa, 0x23,
>>>                         NOMINAL_OPP),
>>> @@ -493,6 +509,74 @@ static void __init vdd_debugfs_init(struct omap_vdd_info *vdd)
>>>                                 &nom_volt_debug_fops);
>>>   }
>>>
>>> +/* voltage transition notification handlers */
>>> +
>>> +/**
>>> + * omap_abb_notify_voltage - voltage change notifier handler for ABB
>>> + * @nb         : notifier block
>>> + * @val                : VOLTSCALE_PRECHANGE or VOLTSCALE_POSTCHANGE
>>> + * @data       : struct omap_volt_change_info for a given voltage domain
>>> + *
>>> + * Sets ABB LDO to either bypass or Forward Body-Bias whenever a voltage
>>> + * change notification is generated.  Voltages marked as FAST will result in
>>> + * FBB operation of ABB LDO and voltages marked as NOMINAL will bypass the
>>> + * LDO.  Does not handle Reverse Body-Bias since there is not benefit for it
>>> + * on any existing silicon.  Returns 0 upon success, negative error code
>>> + * otherwise.
>>> + */
>>> +static int omap_abb_notify_voltage(struct notifier_block *nb,
>>> +               unsigned long val, void *data)
>>> +{
>>> +       struct omap_volt_change_info *v_info;
>>> +       struct omap_vdd_info *vdd;
>>> +       struct omap_volt_data *curr_volt_data, *target_volt_data;
>>> +       int ret = 0;
>>> +
>>> +       if (!nb || IS_ERR(nb) || !data || IS_ERR(data)) {
>>> +               pr_warning("%s: invalid data specified\n", __func__);
>>> +               ret = -EINVAL;
>>> +               goto out;
>>> +       }
>>> +
>>> +       v_info = (struct omap_volt_change_info *)data;
>>> +       vdd = v_info->vdd;
>>> +
>>> +       /* get the voltdata structures for the current&  target voltage */
>>> +       target_volt_data = omap_voltage_get_voltdata(&vdd->voltdm,
>>> +                       v_info->target_volt);
>>> +       curr_volt_data = omap_voltage_get_voltdata(&vdd->voltdm,
>>> +                       v_info->curr_volt);
>>> +
>>> +       /* nothing to do here */
>>> +       if (target_volt_data->abb_opp == curr_volt_data->abb_opp)
>>> +               goto out;
>>> +
>>> +       /*
>>> +        * When the VDD drops from a voltage requiring the ABB LDO to be in
>>> +        * FBB mode to a voltage requiring bypass mode, we must bypass the LDO
>>> +        * before the voltage transition.
>>> +        */
>>> +       if (val == VOLTSCALE_PRECHANGE&&
>>> +                       target_volt_data->abb_opp == NOMINAL_OPP) {
>>> +               ret = vdd->abb.set_opp(&vdd->abb, NOMINAL_OPP);
>>> +
>>> +       /*
>>> +        * When moving from a voltage requiring the ABB LDO to be bypassed to
>>> +        * a voltage requiring FBB mode, we must change the LDO operation
>>> +        * after the voltage transition.
>>> +        */
>>> +       } else if (val == VOLTSCALE_POSTCHANGE&&
>>> +                       target_volt_data->abb_opp == FAST_OPP) {
>>> +               ret = vdd->abb.set_opp(&vdd->abb, FAST_OPP);
>>> +
>>> +       /* invalid combination, bail out */
>>> +       } else
>>> +               ret = -EINVAL;
>>> +
>>> +out:
>>> +       return ret;
>>> +}
>>> +
>>>   /* Voltage scale and accessory APIs */
>>>   static int _pre_volt_scale(struct omap_vdd_info *vdd,
>>>                 unsigned long target_volt, u8 *target_vsel, u8 *current_vsel)
>>> @@ -717,6 +801,142 @@ static int vp_forceupdate_scale_voltage(struct omap_vdd_info *vdd,
>>>         return 0;
>>>   }
>>>
>>> +/**
>>> + * omap3_abb_set_opp - program ABB LDO upon a voltage transition
>>> + *
>>> + * @abb                : ABB instance being programmed
>>> + * @opp_type   : flag for NOMINAL or FAST OPP
>>> + */
>>> +static int omap3_abb_set_opp(struct omap_abb_info *abb, int opp_type)
>>> +{
>>> +       int ret = 0;
>>> +       int timeout;
>>> +
>>> +       /* program for NOMINAL OPP or FAST OPP */
>>> +       omap2_prm_rmw_mod_reg_bits(OMAP3630_OPP_SEL_MASK,
>>> +                       (opp_type<<  OMAP3630_OPP_SEL_SHIFT),
>>> +                       OMAP3430_GR_MOD, abb->setup_offs);
>> Rather than passing a parameter 'opp_type' u can set OPP_SEL bit in
>> SETUP Register in API
>
> I'm not sure I follow.  The opp_type corresponds to the voltage we're
> transitioning to, so that data must be passed in to this generic
> set_opp function.
>
>> omap_abb_notify_voltage where if-else are used to check whether ABB
>> needs to transition or not.
>
> The notifier handles this... it will not execute call set_opp function
> if there is no need to change ABB registers.
>
>>> +
>>> +       /* clear ABB ldo interrupt status */
>>> +       omap2_prm_clear_mod_reg_bits(abb->done_st_mask, OCP_MOD,
>>> +                       abb->irqstatus_mpu_offs);
>>> +
>>> +       /* enable ABB LDO OPP change */
>>> +       omap2_prm_set_mod_reg_bits(OMAP3630_OPP_CHANGE_MASK, OMAP3430_GR_MOD,
>>> +                       abb->setup_offs);
>>> +
>>> +       timeout = 0;
>>> +
>>> +       /* wait until OPP change completes */
>>> +       while ((timeout<  ABB_TRANXDONE_TIMEOUT)&&
>>> +                       (!(omap2_prm_read_mod_reg(OCP_MOD,
>>> +                                                 abb->irqstatus_mpu_offs)&
>>> +                          abb->done_st_mask))) {
>>> +               udelay(1);
>>> +               timeout++;
>>> +       }
>>> +
>>> +       if (timeout == ABB_TRANXDONE_TIMEOUT)
>>> +               pr_warning("%s: TRANXDONE timed out waiting for OPP change\n",
>>> +                               __func__);
>>> +
>>> +       timeout = 0;
>>> +
>>> +       /* Clear all pending TRANXDONE interrupts/status */
>>> +       while (timeout<  ABB_TRANXDONE_TIMEOUT) {
>>> +               omap2_prm_write_mod_reg((1<<  abb->done_st_shift), OCP_MOD,
>>> +                               abb->irqstatus_mpu_offs);
>>> +
>>> +               if (!(omap2_prm_read_mod_reg(OCP_MOD, abb->irqstatus_mpu_offs)
>>> +&  abb->done_st_mask))
>>> +                       break;
>>> +
>>> +               udelay(1);
>>> +               timeout++;
>>> +       }
>>> +
>>> +       if (timeout == ABB_TRANXDONE_TIMEOUT) {
>>> +               pr_warning("%s: TRANXDONE timed out trying to clear status\n",
>>> +                               __func__);
>>> +               ret = -EBUSY;
>>> +       }
>>> +
>>> +       return ret;
>>> +}
>>> +
>>> +/**
>>> + * omap4_abb_set_opp - program ABB LDO upon a voltage transition
>>> + *
>>> + * @abb                : ABB instance being programmed
>>> + * @opp_type   : flag for NOMINAL or FAST OPP
>>> + */
>>> +static int omap4_abb_set_opp(struct omap_abb_info *abb, int opp_type)
>>> +{
>>> +       int ret = 0;
>>> +       int timeout;
>>> +
>>> +       /* program for NOMINAL OPP or FAST OPP */
>>> +       omap4_prminst_rmw_inst_reg_bits(OMAP4430_OPP_SEL_MASK,
>>> +                       (opp_type<<  OMAP4430_OPP_SEL_SHIFT),
>>> +                       OMAP4430_PRM_PARTITION, OMAP4430_PRM_DEVICE_INST,
>>> +                       abb->ctrl_offs);
>>> +
>>> +       /* clear ABB ldo interrupt status */
>>> +       omap4_prminst_rmw_inst_reg_bits(abb->done_st_mask,
>>> +                       (0x0<<  abb->done_st_shift), OMAP4430_PRM_PARTITION,
>>> +                       OMAP4430_PRM_DEVICE_INST, abb->ctrl_offs);
>>> +
>>> +       /* enable ABB LDO OPP change */
>>> +       omap4_prminst_rmw_inst_reg_bits(OMAP4430_OPP_CHANGE_MASK,
>>> +                       (0x1<<  OMAP4430_OPP_CHANGE_SHIFT),
>>> +                       OMAP4430_PRM_PARTITION, OMAP4430_PRM_DEVICE_INST,
>>> +                       abb->ctrl_offs);
>>> +
>> A generic struct can be created which has Masks and shifts of all
>> register offsets  like OMAP4430_OPP_CHANGE_MASK
>> and OMAP3630_ACTIVE_FBB_SEL_MASK whose objects for OMAP3 and OMAP4 can be used.
>
> True.  I chose to have the struct differentiate between VDDs, not OMAP
> chips.  Do others have an opinion on this?  I guess it comes down to
> whether we should have OMAP-specific ABB set_opp functions, and that
> struct data should be per-VDD (like it is in my patch)... OR if we
> should have a generic ABB set_opp function only that works across all
> OMAPs and all data is in the struct whether it is VDD- or
> OMAP-specific.  My problem with the latter solution is that it assumes
> the programming model will not change from OMAP to OMAP...
>
>>> +       timeout = 0;
>>> +
>>> +       /* wait until OPP change completes */
>>> +       while ((timeout<  ABB_TRANXDONE_TIMEOUT)&&
>>> +                       (!(omap4_prminst_read_inst_reg(OMAP4430_PRM_PARTITION,
>>> +                                                      OMAP4430_PRM_DEVICE_INST,
>>> +                                                      abb->irqstatus_mpu_offs)
>>> +&  abb->done_st_mask))) {
>>> +               udelay(1);
>>> +               timeout++;
>>> +       }
>>> +
>>> +       if (timeout == ABB_TRANXDONE_TIMEOUT)
>>> +               pr_warning("%s: TRANXDONE timed out waiting for OPP change\n",
>>> +                               __func__);
>>> +
>>> +       timeout = 0;
>>> +
>>> +       /* Clear all pending TRANXDONE interrupts/status */
>>> +       while (timeout<  ABB_TRANXDONE_TIMEOUT) {
>>> +               omap4_prminst_write_inst_reg((1<<  abb->done_st_shift),
>>> +                               OMAP4430_PRM_PARTITION,
>>> +                               OMAP4430_PRM_DEVICE_INST,
>>> +                               abb->irqstatus_mpu_offs);
>>> +
>>> +               if (!(omap4_prminst_read_inst_reg(OMAP4430_PRM_PARTITION,
>>> +                                               OMAP4430_PRM_DEVICE_INST,
>>> +                                               abb->irqstatus_mpu_offs)
>>> +&  abb->done_st_mask)) {
>>> +                       break;
>>> +
>>> +                       udelay(1);
>>> +                       timeout++;
>>> +               }
>>> +       }
>>> +
>>> +       if (timeout == ABB_TRANXDONE_TIMEOUT) {
>>> +               pr_warning("%s: TRANXDONE timed out trying to clear status\n",
>>> +                               __func__);
>>> +               ret = -EBUSY;
>>> +       }
>>> +
>>> +       return ret;
>>> +}
>>> +
>>>   /* OMAP3 specific voltage init functions */
>>>
>>>   /*
>>> @@ -789,6 +1009,64 @@ static void __init omap3_vc_init(struct omap_vdd_info *vdd)
>>>         is_initialized = true;
>>>   }
>>>
>>> +/**
>>> + * omap3_abb_configure - per-VDD configuration of ABB
>>> + *
>>> + * @abb                : abb instance being initialized
>>> + */
>>> +static int omap3_abb_configure(struct omap_abb_info *abb)
>>> +{
>>> +       int ret = 0;
>>> +       u32 sr2_wt_cnt_val;
>>> +       struct clk *sys_ck;
>>> +       struct omap_vdd_info *vdd;
>>> +
>>> +       if (!abb || IS_ERR(abb)) {
>>> +                       pr_warning("%s: invalid abb\n", __func__);
>>> +                       ret = -EINVAL;
>>> +                       goto out;
>>> +       }
>>> +
>>> +       sys_ck = clk_get(NULL, "sys_ck");
>>> +       if (IS_ERR(sys_ck)) {
>>> +               pr_warning("%s: unable to fetch SYS_CK\n", __func__);
>>> +               ret = -ENODEV;
>>> +               goto out;
>>> +       }
>>> +
>>> +       vdd = container_of(abb, struct omap_vdd_info, abb);
>>> +
>>> +       /* LDO settling time */
>>> +       sr2_wt_cnt_val = clk_get_rate(sys_ck);
>>> +       sr2_wt_cnt_val = sr2_wt_cnt_val / 1000000 / 16;
>>> +
>>> +       omap2_prm_rmw_mod_reg_bits(OMAP3630_SR2_WTCNT_VALUE_MASK,
>>> +                       (sr2_wt_cnt_val<<  OMAP3630_SR2_WTCNT_VALUE_SHIFT),
>>> +                       OMAP3430_GR_MOD, abb->setup_offs);
>>> +
>>> +       /* allow FBB operation */
>>> +       omap2_prm_set_mod_reg_bits(OMAP3630_ACTIVE_FBB_SEL_MASK,
>>> +                       OMAP3430_GR_MOD, abb->setup_offs);
>>> +
>>> +       /* do not allow ACTIVE RBB operation */
>>> +       omap2_prm_set_mod_reg_bits(OMAP3630_ACTIVE_RBB_SEL_MASK,
>>> +                       OMAP3430_GR_MOD, abb->setup_offs);
>>> +
>>> +       /* do not allow SLEEP RBB operation */
>>> +       omap2_prm_set_mod_reg_bits(OMAP3630_SLEEP_RBB_SEL_MASK,
>>> +                       OMAP3430_GR_MOD, abb->setup_offs);
>>> +
>>> +       /* enable ABB LDO */
>>> +       omap2_prm_set_mod_reg_bits(OMAP3630_SR2EN_MASK,
>>> +                       OMAP3430_GR_MOD, abb->ctrl_offs);
>> ABB should n't be enabled in this API rather it should be enabled only
>> when it goes to FBB/RBB mode
>
> I disagree.  I've verified with hw team that this is perfectly safe as
> it leaves ABB ldo in bypass and will follow VDD_xxx voltage.  No
> reason to complicate notifier code with some "if
> (!abb_already_enabled)" check.
>
>>> +
>>> +       /* register the notifier handler */
>>> +       omap_voltage_register_notifier(vdd,&abb->nb);
>>> +
>>> +out:
>>> +       return ret;
>>> +}
>>> +
>>>   /* Sets up all the VDD related info for OMAP3 */
>>>   static int __init omap3_vdd_data_configure(struct omap_vdd_info *vdd)
>>>   {
>>> @@ -824,6 +1102,9 @@ static int __init omap3_vdd_data_configure(struct omap_vdd_info *vdd)
>>>                 vdd->vc_reg.smps_volra_mask = OMAP3430_VOLRA0_MASK;
>>>                 vdd->vc_reg.voltsetup_shift = OMAP3430_SETUP_TIME1_SHIFT;
>>>                 vdd->vc_reg.voltsetup_mask = OMAP3430_SETUP_TIME1_MASK;
>>> +
>>> +               /* configure ABB */
>>> +               vdd->abb.configure(&vdd->abb);
>>>         } else if (!strcmp(vdd->voltdm.name, "core")) {
>>>                 if (cpu_is_omap3630())
>>>                         vdd->volt_data = omap36xx_vddcore_volt_data;
>>> @@ -975,6 +1256,73 @@ static void __init omap4_vc_init(struct omap_vdd_info *vdd)
>>>         is_initialized = true;
>>>   }
>>>
>> To remove code repetition rather than having 2 APIs for abb_configure,
>> I believe 1 API which has generic register offsets struct objects for
>> all platforms
>> (OMAP3 and OMAP4 for now) can be used.
>> This would be scalable for OMAP5+ also.
>
> This is the same as what I've stated above for the ABB set_opp
> function.  We can't be sure what the programming model will be for
> future OMAPs, so should we really do it as your suggest?  It is
> possible that we retain the same set_opp function pointer, and only
> implemenet it once since it can be used by both OMAP3 and OMAP4 using
> more verbose struct data.  OMAP5 might have a different programming
> model altogether, so we will need to retain the set_opp function
> pointer just to be safe.  Thoughts on this?
>
>>
>>> +/**
>>> + * omap4_abb_configure - per-VDD configuration of ABB
>>> + *
>>> + * @abb                : abb instance being initialized
>>> + */
>>> +static int omap4_abb_configure(struct omap_abb_info *abb)
>>> +{
>>> +       int ret = 0;
>>> +       u32 sr2_wt_cnt_val;
>>> +       struct clk *sys_ck;
>>> +       struct omap_vdd_info *vdd;
>>> +
>>> +       if (!abb || IS_ERR(abb)) {
>>> +                       pr_warning("%s: invalid abb\n", __func__);
>>> +                       ret = -EINVAL;
>>> +                       goto out;
>>> +       }
>>> +
>>> +       sys_ck = clk_get(NULL, "sys_clkin_ck");
>>> +       if (IS_ERR(sys_ck)) {
>>> +               pr_warning("%s: unable to fetch SYS_CK", __func__);
>>> +               ret = -ENODEV;
>>> +               goto out;
>>> +       }
>>> +
>>> +       vdd = container_of(abb, struct omap_vdd_info, abb);
>>> +
>>> +       /* LDO settling time */
>>> +       sr2_wt_cnt_val = clk_get_rate(sys_ck);
>>> +       sr2_wt_cnt_val = sr2_wt_cnt_val / 1000000 / 16;
>>> +
>>> +       omap4_prminst_rmw_inst_reg_bits(OMAP4430_SR2_WTCNT_VALUE_MASK,
>>> +                       (sr2_wt_cnt_val<<  OMAP4430_SR2_WTCNT_VALUE_SHIFT),
>>> +                       OMAP4430_PRM_PARTITION, OMAP4430_PRM_DEVICE_INST,
>>> +                       abb->setup_offs);
>>> +
>>> +       /* allow FBB operation */
>>> +       omap4_prminst_rmw_inst_reg_bits(OMAP4430_ACTIVE_FBB_SEL_MASK,
>>> +                       (1<<  OMAP4430_ACTIVE_FBB_SEL_SHIFT),
>>> +                       OMAP4430_PRM_PARTITION, OMAP4430_PRM_DEVICE_INST,
>>> +                       abb->setup_offs);
>>> +
>>> +       /* do not allow ACTIVE RBB operation */
>>> +       omap4_prminst_rmw_inst_reg_bits(OMAP4430_ACTIVE_RBB_SEL_MASK,
>>> +                       (0<<  OMAP4430_ACTIVE_RBB_SEL_SHIFT),
>>> +                       OMAP4430_PRM_PARTITION, OMAP4430_PRM_DEVICE_INST,
>>> +                       abb->setup_offs);
>>> +
>>> +       /* do not allow SLEEP RBB operation */
>>> +       omap4_prminst_rmw_inst_reg_bits(OMAP4430_SLEEP_RBB_SEL_MASK,
>>> +                       (0<<  OMAP4430_SLEEP_RBB_SEL_SHIFT),
>>> +                       OMAP4430_PRM_PARTITION, OMAP4430_PRM_DEVICE_INST,
>>> +                       abb->setup_offs);
>>> +
>>> +       /* enable ABB LDO */
>>> +       omap4_prminst_rmw_inst_reg_bits(OMAP4430_SR2EN_MASK,
>>> +                       (1<<  OMAP4430_SR2EN_SHIFT),
>>> +                       OMAP4430_PRM_PARTITION, OMAP4430_PRM_DEVICE_INST,
>>> +                       abb->setup_offs);
>> Same as above.
>
> Same as my above comment ;-)  This is safe and there is no reason to change it.
>
> Regards,
> Mike
>
>>> +       /* register the notifier handler */
>>> +       omap_voltage_register_notifier(vdd,&abb->nb);
>>> +
>>> +out:
>>> +       return ret;
>>> +}
>>> +
>>>   /* Sets up all the VDD related info for OMAP4 */
>>>   static int __init omap4_vdd_data_configure(struct omap_vdd_info *vdd)
>>>   {
>>> @@ -983,8 +1331,8 @@ static int __init omap4_vdd_data_configure(struct omap_vdd_info *vdd)
>>>
>>>         if (!vdd->pmic_info) {
>>>                 pr_err("%s: PMIC info requried to configure vdd_%s not"
>>> -                       "populated.Hence cannot initialize vdd_%s\n",
>>> -                       __func__, vdd->voltdm.name, vdd->voltdm.name);
>>> +                               "populated.Hence cannot initialize vdd_%s\n",
>>> +                               __func__, vdd->voltdm.name, vdd->voltdm.name);
>>>                 return -EINVAL;
>>>         }
>>>
>>> @@ -1005,6 +1353,9 @@ static int __init omap4_vdd_data_configure(struct omap_vdd_info *vdd)
>>>                 vdd->vc_reg.voltsetup_reg =
>>>                                 OMAP4_PRM_VOLTSETUP_MPU_RET_SLEEP_OFFSET;
>>>                 vdd->prm_irqst_reg = OMAP4_PRM_IRQSTATUS_MPU_2_OFFSET;
>>> +
>>> +               /* configure ABB */
>>> +               vdd->abb.configure(&vdd->abb);
>>>         } else if (!strcmp(vdd->voltdm.name, "core")) {
>>>                 vdd->volt_data = omap44xx_vdd_core_volt_data;
>>>                 vdd->vp_reg.tranxdone_status =
>>> @@ -1032,6 +1383,9 @@ static int __init omap4_vdd_data_configure(struct omap_vdd_info *vdd)
>>>                 vdd->vc_reg.voltsetup_reg =
>>>                                 OMAP4_PRM_VOLTSETUP_IVA_RET_SLEEP_OFFSET;
>>>                 vdd->prm_irqst_reg = OMAP4_PRM_IRQSTATUS_MPU_OFFSET;
>>> +
>>> +               /* configure ABB */
>>> +               vdd->abb.configure(&vdd->abb);
>>>         } else {
>>>                 pr_warning("%s: vdd_%s does not exisit in OMAP4\n",
>>>                         __func__, vdd->voltdm.name);
>>> @@ -1299,6 +1653,7 @@ int omap_voltage_scale_vdd(struct voltagedomain *voltdm,
>>>
>>>         /* load notifier chain data */
>>>         v_info.target_volt = target_volt;
>>> +       v_info.curr_volt = vdd->curr_volt;
>>>         v_info.vdd = vdd;
>>>
>>>         srcu_notifier_call_chain(&vdd->volt_change_notify_chain,
>>> diff --git a/arch/arm/plat-omap/include/plat/voltage.h b/arch/arm/plat-omap/include/plat/voltage.h
>>> index af790bf..07997f7 100644
>>> --- a/arch/arm/plat-omap/include/plat/voltage.h
>>> +++ b/arch/arm/plat-omap/include/plat/voltage.h
>>> @@ -235,8 +235,8 @@ struct omap_vdd_dep_info {
>>>   * @irqstatus_mpu_offs : PRM_IRQSTATUS_MPU* register offset
>>>   * @done_st_shift      : ABB_vdd_DONE_ST shift
>>>   * @done_st_mask       : ABB_vdd_DONE_ST bit mask
>>> + * @nb                 : voltage transition notifier block
>>>   * @configure          : boot-time configuration
>>> - * @nb_handler         : voltage transition notification handler
>>>   * @set_opp            : transition function called from nb_handler
>>>   */
>>>   struct omap_abb_info {
>>> @@ -245,9 +245,8 @@ struct omap_abb_info {
>>>         u8 irqstatus_mpu_offs;
>>>         u8 done_st_shift;
>>>         u32 done_st_mask;
>>> +       struct notifier_block nb;
>>>         int (*configure) (struct omap_abb_info *abb);
>>> -       int (*nb_handler) (struct notifier_block *nb, unsigned long val,
>>> -                       void *data);
>>>         int (*set_opp) (struct omap_abb_info *abb, int opp_type);
>>>   };
>>>
>>> @@ -302,6 +301,7 @@ struct omap_vdd_info {
>>>   */
>>>   struct omap_volt_change_info {
>>>         unsigned long target_volt;
>>> +       unsigned long curr_volt;
>>>         struct omap_vdd_info *vdd;
>>>   };
>>>
>>> --
>>> 1.7.1
>>>
>>> --
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>>
>>
>>
>> --
>> Thanks,
>> Regards,
>> Shweta
>>
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