diff options
| -rw-r--r-- | drivers/power/regulator/stm32-vrefbuf.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/drivers/power/regulator/stm32-vrefbuf.c b/drivers/power/regulator/stm32-vrefbuf.c index 2507735..9213696 100644 --- a/drivers/power/regulator/stm32-vrefbuf.c +++ b/drivers/power/regulator/stm32-vrefbuf.c @@ -43,8 +43,20 @@ static int stm32_vrefbuf_set_enable(struct udevice *dev, bool enable) u32 val; int ret; - clrsetbits_le32(priv->base + STM32_VREFBUF_CSR, STM32_HIZ | STM32_ENVR, - enable ? STM32_ENVR : STM32_HIZ); + if (enable && !(readl(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR)) { + /* + * There maybe an overshoot: + * - when disabling, then re-enabling vrefbuf too quickly + * - or upon platform reset as external capacitor maybe slow + * discharging (VREFBUF is HiZ at reset by default). + * So force active discharge (HiZ=0) for 1ms before enabling. + */ + clrbits_le32(priv->base + STM32_VREFBUF_CSR, STM32_HIZ); + udelay(1000); + } + + clrsetbits_le32(priv->base + STM32_VREFBUF_CSR, STM32_ENVR, + enable ? STM32_ENVR : 0); if (!enable) return 0; |