Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965193AbbDXQVM (ORCPT ); Fri, 24 Apr 2015 12:21:12 -0400 Received: from mail-pa0-f52.google.com ([209.85.220.52]:33512 "EHLO mail-pa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754885AbbDXQVJ (ORCPT ); Fri, 24 Apr 2015 12:21:09 -0400 Message-ID: <553A6D2B.20901@gmail.com> Date: Fri, 24 Apr 2015 09:19:55 -0700 From: Florian Fainelli User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: David Miller CC: vivien.didelot@savoirfairelinux.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@savoirfairelinux.com Subject: Re: [PATCH] net: mdio-gpio: support access that may sleep References: <1429722414-18173-1-git-send-email-vivien.didelot@savoirfairelinux.com> <20150424.110455.2117537129018647564.davem@davemloft.net> <553A67B2.3040400@gmail.com> <20150424.120142.515098054679955418.davem@davemloft.net> In-Reply-To: <20150424.120142.515098054679955418.davem@davemloft.net> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1844 Lines: 44 On 24/04/15 09:01, David Miller wrote: > From: Florian Fainelli > Date: Fri, 24 Apr 2015 08:56:34 -0700 > >> On 24/04/15 08:04, David Miller wrote: >>> From: Vivien Didelot >>> Date: Wed, 22 Apr 2015 13:06:54 -0400 >>> >>>> Some systems using mdio-gpio may use gpio on message based busses, which >>>> require sleeping (e.g. gpio from an I2C I/O expander). >>>> >>>> Since this driver does not use IRQ handler, it is safe to use the >>>> _cansleep suffixed gpio accessors. >>>> >>>> Signed-off-by: Vivien Didelot >>> >>> Since this is down underneath the layer of an MII bus, you cannot >>> universally say that these routines are always called in a sleepable >>> context. >>> >>> The PHY layer, and the driver itself above that, might call these >>> routines from timers, interruptes etc. >> >> The PHY library calls these routines from its state machine workqueue >> for that reason, or from process context (when invoked via ethtool >> ioctl). The only special case is phy_mac_interrupt() which is callable >> from interrupt context, but schedules the state machine workqueue anyway >> to circumvent the "in-interrupt" context. >> >> If we were not doing that, there would be a number of things broken, for >> instance the per-MDIO bus mutex would not protect us from anything. > > Does the link state polling timer use a workqueue in this manner as > well? Yes, the state machine re-schedules its own delayed workqueue at the end of its state processing, no timer/hrtimer is used. -- Florian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/