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SubjectRe: [PATCH] i2c: pca954x: put the mux to disconnected state after resume
Hi Jisheng Zhang,

On Fri, 25 Jul 2014 10:15:59 +0800, Jisheng Zhang wrote:
> pca954x may be power lost during suspend, so after resume we also suffer
> the issue fixed by commit cd823db8b1161ef0d756514d280715a576d65cc3,
>
> "pca954x power-on default is channel 0 connected. If multiple pca954x
> muxes are connected to the same physical I2C bus, the parent bus will
> see channel 0 devices behind both muxes by default."
>
> What's more, when resume bootloader may also operate the mux, so the
> the channel connected after that may not be the one driver thought.
>
> We fix this problem by putting the mux to disconnected state and
> clearing last_chan in the resume hook.
>
> Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> ---
> drivers/i2c/muxes/i2c-mux-pca954x.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
> index 9bd4212..c8c3d58 100644
> --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
> +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
> @@ -273,9 +273,23 @@ static int pca954x_remove(struct i2c_client *client)
> return 0;
> }
>
> +#ifdef CONFIG_PM_SLEEP
> +static int pca954x_resume(struct device *dev)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + struct pca954x *data = i2c_get_clientdata(client);
> +
> + data->last_chan = 0;
> + return i2c_smbus_write_byte(client, 0);
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);

I think you must include <linux/pm.h> for this.

Other than this, the change looks reasonable, you can add:

Reviewed-by: Jean Delvare <jdelvare@suse.de>

(Please note my new e-mail address.)

> +
> static struct i2c_driver pca954x_driver = {
> .driver = {
> .name = "pca954x",
> + .pm = &pca954x_pm,
> .owner = THIS_MODULE,
> },
> .probe = pca954x_probe,


--
Jean Delvare
SUSE L3 Support


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