* [PATCH 1/2] regulator: ti-abb: skip optional parameter for ldo-address
2013-09-27 13:25 [PATCH 0/2] regulator: ti-abb: misc fixes Nishanth Menon
@ 2013-09-27 13:25 ` Nishanth Menon
2013-09-27 14:02 ` Mark Brown
2013-09-27 13:25 ` [PATCH 2/2] regulator: ti-abb: Fix bias voltage glitch in transition to bypass mode with ldo voltage override Nishanth Menon
1 sibling, 1 reply; 5+ messages in thread
From: Nishanth Menon @ 2013-09-27 13:25 UTC (permalink / raw)
To: Liam Girdwood, Mark Brown; +Cc: linux-kernel, Nishanth Menon
On platforms like OMAP4460, LDO override is never used. Even though
efuse determines the ABB bias mode to operate at, ABB voltage is
preconfigured in internal efuse registers without the need for
LDO override for bias voltage. So skip optional parameter if
property is not present.
Signed-off-by: Nishanth Menon <nm@ti.com>
---
drivers/regulator/ti-abb-regulator.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/regulator/ti-abb-regulator.c b/drivers/regulator/ti-abb-regulator.c
index d8e3e12..1e02805 100644
--- a/drivers/regulator/ti-abb-regulator.c
+++ b/drivers/regulator/ti-abb-regulator.c
@@ -765,6 +765,11 @@ static int ti_abb_probe(struct platform_device *pdev)
pname = "ldo-address";
res = platform_get_resource_byname(pdev, IORESOURCE_MEM, pname);
+ if (!res) {
+ dev_dbg(dev, "Missing '%s' IO resource\n", pname);
+ ret = -ENODEV;
+ goto skip_opt;
+ }
abb->ldo_base = devm_ioremap_resource(dev, res);
if (IS_ERR(abb->ldo_base)) {
ret = PTR_ERR(abb->ldo_base);
--
1.7.9.5
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH 2/2] regulator: ti-abb: Fix bias voltage glitch in transition to bypass mode with ldo voltage override
2013-09-27 13:25 [PATCH 0/2] regulator: ti-abb: misc fixes Nishanth Menon
2013-09-27 13:25 ` [PATCH 1/2] regulator: ti-abb: skip optional parameter for ldo-address Nishanth Menon
@ 2013-09-27 13:25 ` Nishanth Menon
2013-09-27 14:01 ` Mark Brown
1 sibling, 1 reply; 5+ messages in thread
From: Nishanth Menon @ 2013-09-27 13:25 UTC (permalink / raw)
To: Liam Girdwood, Mark Brown; +Cc: linux-kernel, Nishanth Menon
As documented in Application Note SWPA117 v2.1(NDA), LDO override has a
requirement that when switching from Bias active + override active
mode(FBB/RBB) to Bypass(nominal) mode, LDO reset must be performed
*after* LDO transitions to Bypass(nominal) mode.
The same rule in reverse applies when switching from a ABB bypass mode
to ABB enabled - LDO override *must* be performed prior to transition to
required ABB mode, if we do not do that, the same glitch takes place.
Currently while transitioning to ABB bypass, we reset the LDO overide
prior to the transition which causes a few milliseconds where ABB LDO
voltage could go all the way to 800mV(based on SoC process node),
during this period, the delta voltage between VDD rail and VBB rail
could cause the system to improperly function.
Signed-off-by: Nishanth Menon <nm@ti.com>
---
drivers/regulator/ti-abb-regulator.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/regulator/ti-abb-regulator.c b/drivers/regulator/ti-abb-regulator.c
index 1e02805..b951a84 100644
--- a/drivers/regulator/ti-abb-regulator.c
+++ b/drivers/regulator/ti-abb-regulator.c
@@ -279,8 +279,12 @@ static int ti_abb_set_opp(struct regulator_dev *rdev, struct ti_abb *abb,
ti_abb_rmw(regs->opp_sel_mask, info->opp_sel, regs->control_reg,
abb->base);
- /* program LDO VBB vset override if needed */
- if (abb->ldo_base)
+ /*
+ * program LDO VBB vset override if needed for !bypass mode
+ * XXX: Do not switch sequence - for !bypass, LDO override reset *must*
+ * be performed *before* switch to bias mode else VBB glitches.
+ */
+ if (abb->ldo_base && info->opp_sel != TI_ABB_NOMINAL_OPP)
ti_abb_program_ldovbb(dev, abb, info);
/* Initiate ABB ldo change */
@@ -295,6 +299,14 @@ static int ti_abb_set_opp(struct regulator_dev *rdev, struct ti_abb *abb,
if (ret)
goto out;
+ /*
+ * Reset LDO VBB vset override bypass mode
+ * XXX: Do not switch sequence - for bypass, LDO override reset *must*
+ * be performed *after* switch to bypass else VBB glitches.
+ */
+ if (abb->ldo_base && info->opp_sel == TI_ABB_NOMINAL_OPP)
+ ti_abb_program_ldovbb(dev, abb, info);
+
out:
return ret;
}
--
1.7.9.5
^ permalink raw reply [flat|nested] 5+ messages in thread