| From af74e231f9585bceb3ad71654f5098efb0bba894 Mon Sep 17 00:00:00 2001 |
| From: Fabrice Gasnier <fabrice.gasnier@st.com> |
| Date: Wed, 4 Mar 2020 09:55:32 +0100 |
| Subject: [PATCH] regulator: stm32-vrefbuf: fix a possible overshoot when |
| re-enabling |
| |
| commit 02fbabd5f4ed182d2c616e49309f5a3efd9ec671 upstream. |
| |
| 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@st.com> |
| Message-Id: <1583312132-20932-1-git-send-email-fabrice.gasnier@st.com> |
| Signed-off-by: Mark Brown <broonie@kernel.org> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/drivers/regulator/stm32-vrefbuf.c b/drivers/regulator/stm32-vrefbuf.c |
| index 8919a5130bec..25f24df9aa82 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 |
| |
