From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Fainelli Subject: Re: [PATCH] net: mdio-gpio: support access that may sleep Date: Fri, 24 Apr 2015 10:36:40 -0700 Message-ID: <553A7F28.4040109@gmail.com> References: <1429722414-18173-1-git-send-email-vivien.didelot@savoirfairelinux.com> <20150424.110455.2117537129018647564.davem@davemloft.net> <553A67B2.3040400@gmail.com> <553A7C73.7040002@cogentembedded.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@savoirfairelinux.com To: Sergei Shtylyov , David Miller , vivien.didelot@savoirfairelinux.com Return-path: Received: from mail-pd0-f176.google.com ([209.85.192.176]:33719 "EHLO mail-pd0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966549AbbDXRhy (ORCPT ); Fri, 24 Apr 2015 13:37:54 -0400 In-Reply-To: <553A7C73.7040002@cogentembedded.com> Sender: netdev-owner@vger.kernel.org List-ID: On 24/04/15 10:25, Sergei Shtylyov wrote: > On 04/24/2015 06:56 PM, Florian Fainelli wrote: > >>>> 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, > > It is not (as we have discussed recently) -- cancel_work_sync() may > sleep. True, but that does not invalidate my comment, I meant to write that this is the only function that you *might* potentially want to call from interrupt context, and yet it does not trigger low-level I/O accesses to the underlying MDIO bus, but instead uses the PHY library state machine workqueue to do that. Thanks for the reminder though, that needs fixing ;) -- Florian