linux-kernel - Applied "regulator: stm32-vrefbuf: fix a possible overshoot when re-enabling" to the regulator tree

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Message-Id:  <applied-1583312132-20932-1-git-send-email-fabrice.gasnier@st.com>
Date:   Wed, 04 Mar 2020 13:57:39 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Fabrice Gasnier <fabrice.gasnier@...com>
Cc:     alexandre.torgue@...com, broonie@...nel.org,
        fabrice.gasnier@...com, lgirdwood@...il.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        Mark Brown <broonie@...nel.org>, mcoquelin.stm32@...il.com
Subject: Applied "regulator: stm32-vrefbuf: fix a possible overshoot when re-enabling" to the regulator tree

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 <fabrice.gasnier@...com>
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 <fabrice.gasnier@...com>
Message-Id: <1583312132-20932-1-git-send-email-fabrice.gasnier@...com>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 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