Hi Jean,
On Fri, 25 Jul 2014 00:15:19 -0700
Jean Delvare <jdelvare@xxxxxxx> wrote:
> 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@xxxxxxxxxxx>
> > ---
> > 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@xxxxxxx>
>
> (Please note my new e-mail address.)
Thanks for reviewing. I have cooked patch v2.
Thanks very much,
Jisheng
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