From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755857AbaIZRcM (ORCPT ); Fri, 26 Sep 2014 13:32:12 -0400 Received: from mail-ig0-f173.google.com ([209.85.213.173]:54761 "EHLO mail-ig0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755042AbaIZRcL (ORCPT ); Fri, 26 Sep 2014 13:32:11 -0400 Date: Fri, 26 Sep 2014 12:32:04 -0500 From: Michael Welling To: Florian Fainelli Cc: linux-kernel@vger.kernel.org, grant.likely@linaro.org, linus.walleij@linaro.org, rjw@rjwysocki.net, gregkh@linuxfoundation.org, Nicolas Ferre Subject: Re: GPIO registration for external Ethernet PHY oscillator enable/disable Message-ID: <20140926173203.GA4459@sysresccd> References: <20140925191722.GA2481@sysresccd> <54247372.40803@gmail.com> <20140926165919.GA3518@sysresccd> <54259F83.5020006@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54259F83.5020006@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 >