Messages in this thread | | | Date | Fri, 26 Sep 2014 11:59:19 -0500 | From | Michael Welling <> | Subject | Re: GPIO registration for external Ethernet PHY oscillator enable/disable |
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On Thu, Sep 25, 2014 at 12:56:34PM -0700, Florian Fainelli wrote: > So, PHY drivers are allowed to provide specialized implementations for > suspend/resume operations that are called by phy_suspend() and > phy_resume(), the current Micrel PHY driver uses the generic > suspend/resume implementation and it is best if we can keep doing that. >
In my situation the defualt phy_suspend is not sufficient. We are looking to use the board for an application that requires a low sleep current. The KZS8081 has a slow oscillator low power mode that is required to meet the requirements.
So I have already overwritten the suspend/resume to send the required commands to the PHY to achieve the slow clock mode.
If you are interested the sequence is explained in the datasheet pg 34: http://www.micrel.com/_PDF/Ethernet/datasheets/KSZ8081MNX-RNB.pdf
> > Can it be handled outside of the PHY driver? > > I see a few possible options: > > - hook a pm_runtime callbacks for your platform, check the device > pointer to make sure this is the PHY device, and when that is the case, > toggle the GPIO accordingly
Not too familiar with the pm_runtime callbacks.
Can you point me to a similar example that is already in the kernel?
> > - add an additional "osc_gpio" configuration parameter passed to the > Ethernet MAC driver (presumably drivers/net/ethernet/cadence/macb.c?) > and toggle the GPIO before and after the calls to the PHY state machine > (phy_suspend, phy_resume, phy_start, phy_stop), that might be simpler >
This seems the wrong place as the oscillator is specific to the PHY.
> - last but not least, make the PHY driver aware of that optional GPIO, > create customized PHY suspend/resume/config_aneg callbacks >
This to me feels like the path of least resistance. Though the driver does not appear to be a platform driver so I am not sure how to pass GPIOs to it. Maybe I am missing something.
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