Re: [PATCH v3 1/4] i2c: designware: Introduce shutdown exported function

Andy Shevchenko
2026-05-05T07:30:01Z

On Mon, May 04, 2026 at 08:15:02PM +0000, William A. Kennington III wrote:
> Introduce an exported shutdown function to safely shutdown the
> DesignWare I2C controller.
>
> This shutdown hook gracefully sets the slave disable bit before disabling
> the controller. This guarantees that any incoming requests from the master
> are immediately NACKed during shutdown, preventing the bus from hanging.

...

> +void i2c_dw_shutdown(struct dw_i2c_dev *dev)
> +{
> + unsigned int con;
> +
> + /*
> + * We only need to handle shutdown for slave mode to ensure
> + * we NACK any incoming master requests. Master mode cleanup
> + * is handled after each transfer in i2c_dw_xfer.

i2c_dw_xfer()

> + */

Since it's a newly added comment, can you switch to use inclusive language?
Same for the whole series related to the commit messages, comments, and
documentation.

> + if (dev->mode != DW_IC_SLAVE)
> + return;
> +
> + /*
> + * To quickly NACK the master during shutdown, we set the slave
> + * disable bit while the controller is still enabled.
> + */
> + regmap_read(dev->map, DW_IC_CON, &con);
> + con |= DW_IC_CON_SLAVE_DISABLE;
> + regmap_write(dev->map, DW_IC_CON, con);
> +
> + i2c_dw_disable(dev);
> +}

> +EXPORT_SYMBOL_GPL(i2c_dw_shutdown);

Can we use namespace?

...

> void __i2c_dw_disable(struct dw_i2c_dev *dev);
> void i2c_dw_disable(struct dw_i2c_dev *dev);

> +void i2c_dw_shutdown(struct dw_i2c_dev *dev);

Isn't more tighten to the probe/remove than this?

> extern void i2c_dw_configure_master(struct dw_i2c_dev *dev);
> extern int i2c_dw_probe_master(struct dw_i2c_dev *dev);