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regulator: spm-regulator: Add additional settling delay for FTS2.5 SMPS

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Based on characterization add 70us settling delay on the voltage UP
to account for warm-up time and ramp-up delays for 0-10% and 90-100%
of the voltage value.

On the voltage ramp-down side add the stepper slew-rate delay and
and an additional 70us margin to avoid voltage updates while the
stepper is in progress. This could lead to voltage over/undershoot
due to buck-internal synchronization failure.

CRs-Fixed: 1036738
Change-Id: Id4230be9c4c981758bbf6860bab1f487a3b57f85
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>
This commit is contained in:
Anirudh Ghayal 2016-06-30 17:10:31 +05:30 • committed by Gerrit - the friendly Code Review server
parent dc9763cc76
commit ccf84a34a4
1 changed files with 18 additions and 2 deletions
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20
drivers/regulator/spm-regulator.c
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@ -1,4 +1,4 @@
/* Copyright (c) 2013-2015, The Linux Foundation. All rights reserved.
/* Copyright (c) 2013-2016, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
@ -118,6 +118,12 @@ static const struct voltage_range hf_range1 = {1550000, 1550000, 3125000,
#define QPNP_FTS2_STEP_MARGIN_NUM 4
#define QPNP_FTS2_STEP_MARGIN_DEN 5
/*
* Settling delay for FTS2.5
* Warm-up=20uS, 0-10% & 90-100% non-linear V-ramp delay = 50uS
*/
#define FTS2P5_SETTLING_DELAY_US 70
/* VSET value to decide the range of ULT SMPS */
#define ULT_SMPS_RANGE_SPLIT 0x60
@ -268,6 +274,7 @@ static int spm_regulator_write_voltage(struct spm_vreg *vreg, int uV)
unsigned vlevel = spm_regulator_uv_to_vlevel(vreg, uV);
bool spm_failed = false;
int rc = 0;
u32 slew_delay;
u8 reg;
if (likely(!vreg->bypass_spm)) {
@ -295,7 +302,16 @@ static int spm_regulator_write_voltage(struct spm_vreg *vreg, int uV)
if (uV > vreg->last_set_uV) {
/* Wait for voltage stepping to complete. */
udelay(DIV_ROUND_UP(uV - vreg->last_set_uV, vreg->step_rate));
slew_delay = DIV_ROUND_UP(vreg->uV - vreg->last_set_uV,
vreg->step_rate);
if (vreg->regulator_type == QPNP_TYPE_FTS2p5)
slew_delay += FTS2P5_SETTLING_DELAY_US;
udelay(slew_delay);
} else if (vreg->regulator_type == QPNP_TYPE_FTS2p5) {
/* add the ramp-down delay */
slew_delay = DIV_ROUND_UP(vreg->last_set_uV - vreg->uV,
vreg->step_rate) + FTS2P5_SETTLING_DELAY_US;
udelay(slew_delay);
}
vreg->last_set_uV = uV;