On Fri, Sep 26, 2014 at 10:16:51AM -0700, Florian Fainelli wrote: > On 09/26/2014 09:59 AM, Michael Welling wrote: > > 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? > > drivers/sh/pm_runtime.c is a simple example, there might others in the > OMAP code. > > > > >> > >> - 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. > > Yes and no, this might feel like the wrong place, but ultimately, the > Ethernet MAC is a consumer of the PHY device, and is in control, through > the PHY library of how and when the PHY gets to be powered off.
This is a good point. This driver also has the added advantage that it is a platform driver so the GPIO could more easily be registered via the device tree. Lets try this option first and see how it works out. > > > > >> - 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. > > If your platform uses Device Tree, you need to add a probe() and > remove() callbacks to the micrel PHY driver, and fetch the gpio resource > from there. > > For non-Device Tree, we might have to find an another to specify such > auxiliary information, but traditionally, people have been using the > help of the Ethernet MAC driver to provide additional information down > to the PHY driver. > -- > Florian > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
