There maybe an overshoot, when disabling, then re-enabling vrefbuf
too quickly. VREFBUF is used by ADC/DAC on some boards. When re-enabling
too quickly, an overshoot on the reference voltage make the conversions
inaccurate for a short period of time.
- Don't put the VREFBUF in HiZ when disabling, to force an active
discharge.
- Enforce a 1ms OFF/ON delay
Fixes: 0cdbf481e927 ("regulator: Add support for stm32-vrefbuf")
Signed-off-by: Fabrice Gasnier <[email protected]>
---
drivers/regulator/stm32-vrefbuf.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/regulator/stm32-vrefbuf.c b/drivers/regulator/stm32-vrefbuf.c
index bdfaf7e..992bc18 100644
--- a/drivers/regulator/stm32-vrefbuf.c
+++ b/drivers/regulator/stm32-vrefbuf.c
@@ -88,7 +88,7 @@ static int stm32_vrefbuf_disable(struct regulator_dev *rdev)
}
val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
- val = (val & ~STM32_ENVR) | STM32_HIZ;
+ val &= ~STM32_ENVR;
writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
pm_runtime_mark_last_busy(priv->dev);
@@ -175,6 +175,7 @@ static const struct regulator_desc stm32_vrefbuf_regu = {
.volt_table = stm32_vrefbuf_voltages,
.n_voltages = ARRAY_SIZE(stm32_vrefbuf_voltages),
.ops = &stm32_vrefbuf_volt_ops,
+ .off_on_delay = 1000,
.type = REGULATOR_VOLTAGE,
.owner = THIS_MODULE,
};
--
2.7.4
The patch
regulator: stm32-vrefbuf: fix a possible overshoot when re-enabling
has been applied to the regulator tree at
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git
All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.
You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.
If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.
Please add any relevant lists and maintainers to the CCs when replying
to this mail.
Thanks,
Mark
From 02fbabd5f4ed182d2c616e49309f5a3efd9ec671 Mon Sep 17 00:00:00 2001
From: Fabrice Gasnier <[email protected]>
Date: Wed, 4 Mar 2020 09:55:32 +0100
Subject: [PATCH] regulator: stm32-vrefbuf: fix a possible overshoot when
re-enabling
There maybe an overshoot, when disabling, then re-enabling vrefbuf
too quickly. VREFBUF is used by ADC/DAC on some boards. When re-enabling
too quickly, an overshoot on the reference voltage make the conversions
inaccurate for a short period of time.
- Don't put the VREFBUF in HiZ when disabling, to force an active
discharge.
- Enforce a 1ms OFF/ON delay
Fixes: 0cdbf481e927 ("regulator: Add support for stm32-vrefbuf")
Signed-off-by: Fabrice Gasnier <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Mark Brown <[email protected]>
---
drivers/regulator/stm32-vrefbuf.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/regulator/stm32-vrefbuf.c b/drivers/regulator/stm32-vrefbuf.c
index bdfaf7edb75a..992bc18101ef 100644
--- a/drivers/regulator/stm32-vrefbuf.c
+++ b/drivers/regulator/stm32-vrefbuf.c
@@ -88,7 +88,7 @@ static int stm32_vrefbuf_disable(struct regulator_dev *rdev)
}
val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
- val = (val & ~STM32_ENVR) | STM32_HIZ;
+ val &= ~STM32_ENVR;
writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
pm_runtime_mark_last_busy(priv->dev);
@@ -175,6 +175,7 @@ static const struct regulator_desc stm32_vrefbuf_regu = {
.volt_table = stm32_vrefbuf_voltages,
.n_voltages = ARRAY_SIZE(stm32_vrefbuf_voltages),
.ops = &stm32_vrefbuf_volt_ops,
+ .off_on_delay = 1000,
.type = REGULATOR_VOLTAGE,
.owner = THIS_MODULE,
};
--
2.20.1