On Fri, May 31, 2013 at 23:37:02, Kevin Hilman wrote:
> +Linus Walleij (pinctrl maintainer)
>
> Hebbar Gururaja <gururaja.hebbar@xxxxxx> writes:
>
> > Amend the I2C omap pin controller to optionally take a pin control
> > handle and set the state of the pins to:
> >
> > - "default" on boot, resume and before performing an i2c transfer
> > - "idle" after initial default, after resume default, and after each
> > i2c xfer
> > - "sleep" on suspend()
> >
> > By optionally putting the pins into sleep state in the suspend callback
> > we can accomplish two things.
> > - One is to minimize current leakage from pins and thus save power,
> > - second, we can prevent the IP from driving pins output in an
> > uncontrolled manner, which may happen if the power domain drops the
> > domain regulator.
> >
> > Note:
> > A .suspend & .resume callback is added which simply puts the pins to sleep
> > state upon suspend & are moved to default & idle state upon resume.
> >
> > If any of the above pin states are missing in dt, a warning message
> > about the missing state is displayed.
> > If certain pin-states are not available, to remove this warning message
> > pass respective state name with null phandler.
> >
> > (Changes based on i2c-nomadik.c)
> >
> > Signed-off-by: Hebbar Gururaja <gururaja.hebbar@xxxxxx>
> > Cc: Tony Lindgren <tony@xxxxxxxxxxx>
> > Cc: Wolfram Sang <wsa@xxxxxxxxxxxxx>
> > Cc: linux-omap@xxxxxxxxxxxxxxx
> > Cc: linux-i2c@xxxxxxxxxxxxxxx
>
> [...]
>
> > @@ -1123,14 +1138,47 @@ omap_i2c_probe(struct platform_device *pdev)
> > dev->set_mpu_wkup_lat = pdata->set_mpu_wkup_lat;
> > }
> >
> > - dev->pins = devm_pinctrl_get_select_default(&pdev->dev);
> > - if (IS_ERR(dev->pins)) {
> > - if (PTR_ERR(dev->pins) == -EPROBE_DEFER)
> > + dev->pinctrl = devm_pinctrl_get(&pdev->dev);
> > + if (!IS_ERR(dev->pinctrl)) {
> > + dev->pins_default = pinctrl_lookup_state(dev->pinctrl,
> > + PINCTRL_STATE_DEFAULT);
>
> This part is already done by probe in driver core, why does it need to
> be done again. dev->pins->default_state should already have this.
> (c.f. pinctrl_bind_pins() in drivers/base/pinctrl.c)
>
> But that brings up a bigger question about whether or not we should be
> doing the rest of this (idle/sleep) pin management in the drivers or in
> the driver core as well. I would much prefer it be handled by the
> driver core.
>
> In fact, since these are all PM related events, it should probably be
> handled by the PM core and seems pretty straight forward to do so.
Let me pull out some info about these and come back
>
> Kevin
>
Regards,
Gururaja
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