From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: Re: [PATCH 01/10] i2c: add suspended flag and accessors for i2c adapters Date: Wed, 19 Dec 2018 19:36:54 +0100 Message-ID: <83b17734-2437-5a04-8843-e18ccf7ad398@redhat.com> References: <20181219164827.20985-1-wsa+renesas@sang-engineering.com> <20181219164827.20985-2-wsa+renesas@sang-engineering.com> <20181219172250.ytronxeq2yc4vp4r@wunner.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20181219172250.ytronxeq2yc4vp4r@wunner.de> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Lukas Wunner , Wolfram Sang Cc: linux-i2c@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Wolfram Sang , linux-kernel@vger.kernel.org List-Id: linux-pm@vger.kernel.org Hi, On 19-12-18 18:22, Lukas Wunner wrote: > On Wed, Dec 19, 2018 at 05:48:17PM +0100, Wolfram Sang wrote: >> +static inline void i2c_mark_adapter_suspended(struct i2c_adapter *adap) >> +{ >> + i2c_lock_bus(adap, I2C_LOCK_ROOT_ADAPTER); >> + set_bit(I2C_ALF_IS_SUSPENDED, &adap->locked_flags); >> + i2c_unlock_bus(adap, I2C_LOCK_ROOT_ADAPTER); >> +} > > This looks like a duplication of the is_suspended flag in struct dev_pm_info. > Any reason why you can't use that? If so, it would be good to document the > reason in the commit message. Oh, that is a very good point and that one only gets set on system suspend and not on resume suspend, working around the problems with the i2c-designware driver. I think this might be as simple as adding: if (WARN_ON(adap->dev.parent->power.is_suspended)) return -ESHUTDOWN; To __i2c_transfer (and document the -ESHUTDOWN) combined with removing all the now no longer DIY code from various bus drivers. Regards, Hans > > If the point is to constrain refusal of transfers in suspended state to > certain drivers, those drivers could opt in to that functionality by > setting a flag, and the i2c core could then gate refusal based on > that flag and the is_suspended flag in struct dev_pm_info. > > Also, why is it necessary to take a lock to perform an atomic bitop? > (Sorry if that's a dumb question, seems non-obvious to me.) > > Thanks, > > Lukas >