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

[Sean Nyekjaer]

Hi,


On Monday, 27 July 2026 at 12:22, Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> wrote:

> On 27.07.2026 11:48:59, Sean Nyekjaer wrote:
> > Put the tcan4x5x transceiver into sleep mode when the driver is
> 
> Ah, the device has an internal transceiver.
> 
> > 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.
> >
> > Note that the reset pin is needed to bring the device out of sleep
> > and back into standby mode again.
> 
> Please add a comment, that the reset pin is needed and maybe refer to
> "8.4.3 Sleep Mode" of https://www.ti.com/lit/gpn/tcan4550

Will do.
> 
> Does it still work, if you move the regmap_update_bits() to
> tcan4x5x_power_enable()?

In our use-case, we don't have control over Vsup. It's directly wired to 12V from the car.
But toggling Vsup will get the tcan4x5x into standby mode again.

Maybe:
if (priv->reset_gpio && priv->power == NULL) ?

> 
> > Signed-off-by: Sean Nyekjaer <sean@xxxxxxxxxx>
> > ---
> > I havn't come across any drivers that leaves the devices in the lowest
> > power mode when unbinded. But we need this to enter our lowest power
> > mode in suspend.
> > If it doesn't fit in, I'm happy to carry this out of tree...
> 
> The mcp251xfd driver puts the device into sleep mode.
> 
> regards,
> Marc
> 
> -- 
> Pengutronix e.K.                 | Marc Kleine-Budde          |
> Embedded Linux                   | https://www.pengutronix.de |
> Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
> Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |
> 

/Sean