From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932360AbdCUKSi (ORCPT ); Tue, 21 Mar 2017 06:18:38 -0400 Received: from fllnx209.ext.ti.com ([198.47.19.16]:40368 "EHLO fllnx209.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932263AbdCUKSf (ORCPT ); Tue, 21 Mar 2017 06:18:35 -0400 Subject: Re: [RFC PATCH] net: phy: Don't miss phy_suspend() on PHY_HALTED for PHYs with interrupts To: Florian Fainelli , Andrew Lunn References: <1489585887-8683-1-git-send-email-rogerq@ti.com> <20170315140811.GD21021@lunn.ch> <6ec42ad7-0be3-f6c5-2ded-27bf3adbab23@ti.com> <20170315154912.GE21021@lunn.ch> <6d3f2d3c-69e0-43a4-9862-126a7c173934@ti.com> CC: , , , From: Roger Quadros Message-ID: <625a9ee1-ea65-3991-2f5c-df95ddf12700@ti.com> Date: Tue, 21 Mar 2017 12:09:55 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20/03/17 18:41, Florian Fainelli wrote: > On 03/16/2017 12:46 AM, Roger Quadros wrote: >> On 15/03/17 17:49, Andrew Lunn wrote: >>> On Wed, Mar 15, 2017 at 05:00:08PM +0200, Roger Quadros wrote: >>>> Andrew, >>>> >>>> On 15/03/17 16:08, Andrew Lunn wrote: >>>>> On Wed, Mar 15, 2017 at 03:51:27PM +0200, Roger Quadros wrote: >>>>>> Since commit 3c293f4e08b5 ("net: phy: Trigger state machine on state change and not polling.") >>>>>> phy_suspend() doesn't get called as part of phy_stop() for PHYs using >>>>>> interrupts because the phy state machine is never triggered after a phy_stop(). >>>>>> >>>>>> Explicitly trigger the PHY state machine so that it can >>>>>> see the new PHY state (HALTED) and suspend the PHY. >>>>>> >>>>>> Signed-off-by: Roger Quadros >>>>> >>>>> Hi Roger >>>>> >>>>> This seems sensible. It mirrors what phy_start() does. >>>>> >>>>> Reviewed-by: Andrew Lunn >>>> >>>> The reason for this being an RFC was the following comment just before >>>> where I add the phy_trigger_machine() >>>> >>>> /* Cannot call flush_scheduled_work() here as desired because >>>> * of rtnl_lock(), but PHY_HALTED shall guarantee phy_change() >>>> * will not reenable interrupts. >>>> */ >>>> >>>> Is this comment still applicable? If yes, is it OK to call >>>> phy_trigger_machine() there? >>> >>> Humm, good question. >>> >>> My _guess_ would be, calling it with sync=True could >>> deadlock. sync=False is probably safe. But lets see what Florian says. >> >> I agree that we should use phy_trigger_machine() with sync=False. >> >>> >>>> >>>>> >>>>> It does however lead to a follow up question. Are there other places >>>>> phydev->state is changed and it is missing a phy_trigger_machine()? >>>>> >>>> >>>> One other place I think we should add phy_trigger_machine() is phy_start_aneg(). >>> >>> Humm, that might get us into a tight loop. >>> >>> phy_start_aneg() kicks the phy driver to start autoneg and sets >>> phydev->state = PHY_AN. >>> >>> phy_trigger_machine() triggers the state machine immediately. >>> >>> In state PHY_AN, we check if aneg is done. If not, it sets needs_aneg >>> = true. At the end of the state machine, this then calls >>> phy_start_aneg(), and it all starts again. >>> >>> We are missing the 1s delay we have with polling. So for >>> phy_start_aneg(), we might need a phy_delayed_trigger_machine(), which >>> waits a second before doing anything? >> >> I think that should do the trick. >> >> How about this? > > This sounds like a possible fix indeed, however I would like to better > assess the impact on non interrupt driven PHYs before rolling such a change. Is it safer if I add a check to do this only for interrupt driven PHYs? e.g. diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c index 4b855f2..e0f5755 100644 --- a/drivers/net/phy/phy.c +++ b/drivers/net/phy/phy.c @@ -630,6 +630,9 @@ int phy_start_aneg(struct phy_device *phydev) out_unlock: mutex_unlock(&phydev->lock); + if (!err && phy_interrupt_is_valid(phydev)) + queue_delayed_work(system_power_efficient_wq, &phydev->state_queue, HZ); + return err; } EXPORT_SYMBOL(phy_start_aneg); -- 2.7.4 -- cheers, -roger