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[PATCH v4] can: tcan4x5x: put tcan into sleep when removing driver

Sean Nyekjaer posted 1 patch 1 month, 4 weeks ago
There is a newer version of this series
drivers/net/can/m_can/tcan4x5x-core.c | 29 +++++++++++++++++++++++----
1 file changed, 25 insertions(+), 4 deletions(-)
[PATCH v4] can: tcan4x5x: put tcan into sleep when removing driver
Posted by Sean Nyekjaer 1 month, 4 weeks ago 
Put the tcan4x5x transceiver into sleep mode when the driver is
removed, instead of leaving it in its current operating mode.
This reduces power consumption(3mA@12V) once the driver is
no longer bound to the device.

Signed-off-by: Sean Nyekjaer <sean@geanix.com>
---
Changes since v1:
 - Moved enter sleep mode into tcan4x5x_power_enable()

Changes since v2:
 - Added comment about RST pin
 - Fixed all calls to tcan4x5x_power_enable()

Changes since v3:
 - When powering off, always put the device into sleep mode (if the RST pin is
   present). This will ensure the device is in sleep mode even if the
   power regulator is shared.

 drivers/net/can/m_can/tcan4x5x-core.c | 29 +++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/m_can/tcan4x5x-core.c b/drivers/net/can/m_can/tcan4x5x-core.c
index 31cc9d0abd45..d8fd219a27cc 100644
--- a/drivers/net/can/m_can/tcan4x5x-core.c
+++ b/drivers/net/can/m_can/tcan4x5x-core.c
@@ -211,8 +211,29 @@ static int tcan4x5x_write_fifo(struct m_can_classdev *cdev,
 	return regmap_bulk_write(priv->regmap, TCAN4X5X_MRAM_START + addr_offset, val, val_count);
 }
 
-static int tcan4x5x_power_enable(struct regulator *reg, int enable)
+static int tcan4x5x_power_enable(struct tcan4x5x_priv *priv, int enable)
 {
+	struct regulator *reg = priv->power;
+	int ret;
+
+	/*
+	 * Put the device into sleep mode if the RST pin is available,
+	 * since a wake-up event, RST pin toggle, or power cycle are the only
+	 * ways to exit sleep mode.
+	 * Redundant if the regulator is exclusive to this device, but that
+	 * can't be determined here.
+	 *
+	 * Datasheet: TCAN4550, section "8.4.3 Sleep Mode"
+	 * https://www.ti.com/lit/gpn/tcan4550
+	 */
+	if (priv->reset_gpio && !enable) {
+		ret = regmap_update_bits(priv->regmap, TCAN4X5X_CONFIG,
+					 TCAN4X5X_MODE_SEL_MASK,
+					 TCAN4X5X_MODE_SLEEP);
+		if (ret)
+			return ret;
+	}
+
 	if (IS_ERR_OR_NULL(reg))
 		return 0;
 
@@ -476,7 +497,7 @@ static int tcan4x5x_can_probe(struct spi_device *spi)
 		goto out_m_can_class_free_dev;
 	}
 
-	ret = tcan4x5x_power_enable(priv->power, 1);
+	ret = tcan4x5x_power_enable(priv, 1);
 	if (ret) {
 		dev_err(&spi->dev, "Enabling regulator failed %pe\n",
 			ERR_PTR(ret));
@@ -531,7 +552,7 @@ static int tcan4x5x_can_probe(struct spi_device *spi)
 	return 0;
 
 out_power:
-	tcan4x5x_power_enable(priv->power, 0);
+	tcan4x5x_power_enable(priv, 0);
  out_m_can_class_free_dev:
 	m_can_class_free_dev(mcan_class->net);
 	return ret;
@@ -543,7 +564,7 @@ static void tcan4x5x_can_remove(struct spi_device *spi)
 
 	m_can_class_unregister(&priv->cdev);
 
-	tcan4x5x_power_enable(priv->power, 0);
+	tcan4x5x_power_enable(priv, 0);
 
 	m_can_class_free_dev(priv->cdev.net);
 }
-- 
2.55.0
Re: [PATCH v4] can: tcan4x5x: put tcan into sleep when removing driver
Posted by Marc Kleine-Budde 1 month, 3 weeks ago 
On 04.08.2026 13:30:26, Sean Nyekjaer wrote:
> Put the tcan4x5x transceiver into sleep mode when the driver is
> removed, instead of leaving it in its current operating mode.
> This reduces power consumption(3mA@12V) once the driver is
> no longer bound to the device.
>
> Signed-off-by: Sean Nyekjaer <sean@geanix.com>
> ---
> Changes since v1:
>  - Moved enter sleep mode into tcan4x5x_power_enable()
>
> Changes since v2:
>  - Added comment about RST pin
>  - Fixed all calls to tcan4x5x_power_enable()
>
> Changes since v3:
>  - When powering off, always put the device into sleep mode (if the RST pin is
>    present). This will ensure the device is in sleep mode even if the
>    power regulator is shared.
>
>  drivers/net/can/m_can/tcan4x5x-core.c | 29 +++++++++++++++++++++++----
>  1 file changed, 25 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/can/m_can/tcan4x5x-core.c b/drivers/net/can/m_can/tcan4x5x-core.c
> index 31cc9d0abd45..d8fd219a27cc 100644
> --- a/drivers/net/can/m_can/tcan4x5x-core.c
> +++ b/drivers/net/can/m_can/tcan4x5x-core.c
> @@ -211,8 +211,29 @@ static int tcan4x5x_write_fifo(struct m_can_classdev *cdev,
>  	return regmap_bulk_write(priv->regmap, TCAN4X5X_MRAM_START + addr_offset, val, val_count);
>  }
>
> -static int tcan4x5x_power_enable(struct regulator *reg, int enable)
> +static int tcan4x5x_power_enable(struct tcan4x5x_priv *priv, int enable)
>  {
> +	struct regulator *reg = priv->power;
> +	int ret;
> +
> +	/*
> +	 * Put the device into sleep mode if the RST pin is available,
> +	 * since a wake-up event, RST pin toggle, or power cycle are the only
> +	 * ways to exit sleep mode.
> +	 * Redundant if the regulator is exclusive to this device, but that
> +	 * can't be determined here.
> +	 *
> +	 * Datasheet: TCAN4550, section "8.4.3 Sleep Mode"
> +	 * https://www.ti.com/lit/gpn/tcan4550
> +	 */
> +	if (priv->reset_gpio && !enable) {
> +		ret = regmap_update_bits(priv->regmap, TCAN4X5X_CONFIG,
> +					 TCAN4X5X_MODE_SEL_MASK,
> +					 TCAN4X5X_MODE_SLEEP);
> +		if (ret)
> +			return ret;

As sashiko pointed out, maybe only log a error here and continue.

regards,
Marc

-- 
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