Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933967AbaGQO6V (ORCPT ); Thu, 17 Jul 2014 10:58:21 -0400 Received: from mail-ig0-f174.google.com ([209.85.213.174]:43376 "EHLO mail-ig0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932139AbaGQO6S (ORCPT ); Thu, 17 Jul 2014 10:58:18 -0400 MIME-Version: 1.0 In-Reply-To: <1405608520-5644-1-git-send-email-hechtb@gmail.com> References: <1405608520-5644-1-git-send-email-hechtb@gmail.com> Date: Thu, 17 Jul 2014 16:58:17 +0200 Message-ID: Subject: Re: [PATCH v2 1/5] i2c: Don't start transfers when suspended From: Bastian Hecht To: linux-i2c@vger.kernel.org Cc: Linux-SH , Tomoya MORINAGA , Wolfram Sang , "linux-arm-kernel@lists.infradead.org" , Bastian Hecht , open list , linux-pm@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I want to add the remark that I can't help further on the patch series in the next month about. So this is free to be taken/ignored/modified without any approval by my side. Have fun coding, Bastian 2014-07-17 16:48 GMT+02:00 Bastian Hecht : > i2c transfer requests come in very uncontrolled, like from interrupt routines. > We might be suspended when this happens. To avoid i2c timeouts caused by > powered down busses we check for suspension. > > Several bus drivers handle this problem on their own. We can clean things up > by moving the protection mechanism into the core. > > Signed-off-by: Bastian Hecht > --- > changelog v2: > > - commit message extended. > - initialization added for adap->suspended > - swapped branch for increased performance > > > drivers/i2c/i2c-core.c | 25 ++++++++++++++++++++++++- > include/linux/i2c.h | 1 + > 2 files changed, 25 insertions(+), 1 deletion(-) > > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c > index 7c7f4b8..b15dc20 100644 > --- a/drivers/i2c/i2c-core.c > +++ b/drivers/i2c/i2c-core.c > @@ -343,6 +343,13 @@ static int i2c_legacy_resume(struct device *dev) > static int i2c_device_pm_suspend(struct device *dev) > { > const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; > + struct i2c_adapter *adap = i2c_verify_adapter(dev); > + > + if (adap) { > + i2c_lock_adapter(adap); > + adap->suspended = true; > + i2c_unlock_adapter(adap); > + } > > if (pm) > return pm_generic_suspend(dev); > @@ -353,6 +360,13 @@ static int i2c_device_pm_suspend(struct device *dev) > static int i2c_device_pm_resume(struct device *dev) > { > const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; > + struct i2c_adapter *adap = i2c_verify_adapter(dev); > + > + if (adap) { > + i2c_lock_adapter(adap); > + adap->suspended = false; > + i2c_unlock_adapter(adap); > + } > > if (pm) > return pm_generic_resume(dev); > @@ -1243,6 +1257,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap) > dev_set_name(&adap->dev, "i2c-%d", adap->nr); > adap->dev.bus = &i2c_bus_type; > adap->dev.type = &i2c_adapter_type; > + adap->suspended = false; > res = device_register(&adap->dev); > if (res) > goto out_list; > @@ -1819,7 +1834,10 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) > i2c_lock_adapter(adap); > } > > - ret = __i2c_transfer(adap, msgs, num); > + if (!adap->suspended) > + ret = __i2c_transfer(adap, msgs, num); > + else > + ret = -EIO; > i2c_unlock_adapter(adap); > > return ret; > @@ -2577,6 +2595,10 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags, > > if (adapter->algo->smbus_xfer) { > i2c_lock_adapter(adapter); > + if (adapter->suspended) { > + res = -EIO; > + goto unlock; > + } > > /* Retry automatically on arbitration loss */ > orig_jiffies = jiffies; > @@ -2590,6 +2612,7 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags, > orig_jiffies + adapter->timeout)) > break; > } > +unlock: > i2c_unlock_adapter(adapter); > > if (res != -EOPNOTSUPP || !adapter->algo->master_xfer) > diff --git a/include/linux/i2c.h b/include/linux/i2c.h > index b556e0a..af08c75 100644 > --- a/include/linux/i2c.h > +++ b/include/linux/i2c.h > @@ -434,6 +434,7 @@ struct i2c_adapter { > int timeout; /* in jiffies */ > int retries; > struct device dev; /* the adapter device */ > + unsigned int suspended:1; > > int nr; > char name[48]; > -- > 1.9.1 > -- 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/