From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754372AbeDIU5B (ORCPT ); Mon, 9 Apr 2018 16:57:01 -0400 Received: from lelnx194.ext.ti.com ([198.47.27.80]:31846 "EHLO lelnx194.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754076AbeDIU47 (ORCPT ); Mon, 9 Apr 2018 16:56:59 -0400 Subject: Re: [PATCH 1/2] i2c: sprd: Prevent i2c accesses after suspend is called To: Baolin Wang , CC: , , References: <99031524fa147e72451d26f54b24f36093c0d3fa.1523255712.git.baolin.wang@linaro.org> From: Grygorii Strashko Message-ID: <557074eb-e988-8ff5-bec0-c85bb9dcb8ec@ti.com> Date: Mon, 9 Apr 2018 15:56:52 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <99031524fa147e72451d26f54b24f36093c0d3fa.1523255712.git.baolin.wang@linaro.org> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/09/2018 01:40 AM, Baolin Wang wrote: > Add one flag to indicate if the i2c controller has been in suspend state, > which can prevent i2c accesses after i2c controller is suspended following > system suspend. This usually indicates some bigger problem - there should be no i2c access to the I2C driver once it's suspended. But if happens - it means suspend dependencies between drivers are broken or there some scheduling primitives are not disabled properly. (possible sources - kthreads, delayed works, timers or even threaded irqs) > > Signed-off-by: Baolin Wang > --- > drivers/i2c/busses/i2c-sprd.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/drivers/i2c/busses/i2c-sprd.c b/drivers/i2c/busses/i2c-sprd.c > index 25fcc3c..2fdad63 100644 > --- a/drivers/i2c/busses/i2c-sprd.c > +++ b/drivers/i2c/busses/i2c-sprd.c > @@ -86,6 +86,7 @@ struct sprd_i2c { > u32 count; > int irq; > int err; > + bool is_suspended; > }; > > static void sprd_i2c_set_count(struct sprd_i2c *i2c_dev, u32 count) > @@ -283,6 +284,9 @@ static int sprd_i2c_master_xfer(struct i2c_adapter *i2c_adap, > struct sprd_i2c *i2c_dev = i2c_adap->algo_data; > int im, ret; > > + if (i2c_dev->is_suspended) > + return -EBUSY; > + > ret = pm_runtime_get_sync(i2c_dev->dev); > if (ret < 0) > return ret; > @@ -586,11 +590,23 @@ static int sprd_i2c_remove(struct platform_device *pdev) > > static int __maybe_unused sprd_i2c_suspend_noirq(struct device *pdev) > { > + struct sprd_i2c *i2c_dev = dev_get_drvdata(pdev); > + > + i2c_lock_adapter(&i2c_dev->adap); > + i2c_dev->is_suspended = true; > + i2c_unlock_adapter(&i2c_dev->adap); > + > return pm_runtime_force_suspend(pdev); > } > > static int __maybe_unused sprd_i2c_resume_noirq(struct device *pdev) > { > + struct sprd_i2c *i2c_dev = dev_get_drvdata(pdev); > + > + i2c_lock_adapter(&i2c_dev->adap); > + i2c_dev->is_suspended = false; > + i2c_unlock_adapter(&i2c_dev->adap); > + > return pm_runtime_force_resume(pdev); > } > > -- regards, -grygorii From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grygorii Strashko Subject: Re: [PATCH 1/2] i2c: sprd: Prevent i2c accesses after suspend is called Date: Mon, 9 Apr 2018 15:56:52 -0500 Message-ID: <557074eb-e988-8ff5-bec0-c85bb9dcb8ec@ti.com> References: <99031524fa147e72451d26f54b24f36093c0d3fa.1523255712.git.baolin.wang@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <99031524fa147e72451d26f54b24f36093c0d3fa.1523255712.git.baolin.wang@linaro.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Baolin Wang , wsa@the-dreams.de Cc: broonie@kernel.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-i2c@vger.kernel.org On 04/09/2018 01:40 AM, Baolin Wang wrote: > Add one flag to indicate if the i2c controller has been in suspend state, > which can prevent i2c accesses after i2c controller is suspended following > system suspend. This usually indicates some bigger problem - there should be no i2c access to the I2C driver once it's suspended. But if happens - it means suspend dependencies between drivers are broken or there some scheduling primitives are not disabled properly. (possible sources - kthreads, delayed works, timers or even threaded irqs) > > Signed-off-by: Baolin Wang > --- > drivers/i2c/busses/i2c-sprd.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/drivers/i2c/busses/i2c-sprd.c b/drivers/i2c/busses/i2c-sprd.c > index 25fcc3c..2fdad63 100644 > --- a/drivers/i2c/busses/i2c-sprd.c > +++ b/drivers/i2c/busses/i2c-sprd.c > @@ -86,6 +86,7 @@ struct sprd_i2c { > u32 count; > int irq; > int err; > + bool is_suspended; > }; > > static void sprd_i2c_set_count(struct sprd_i2c *i2c_dev, u32 count) > @@ -283,6 +284,9 @@ static int sprd_i2c_master_xfer(struct i2c_adapter *i2c_adap, > struct sprd_i2c *i2c_dev = i2c_adap->algo_data; > int im, ret; > > + if (i2c_dev->is_suspended) > + return -EBUSY; > + > ret = pm_runtime_get_sync(i2c_dev->dev); > if (ret < 0) > return ret; > @@ -586,11 +590,23 @@ static int sprd_i2c_remove(struct platform_device *pdev) > > static int __maybe_unused sprd_i2c_suspend_noirq(struct device *pdev) > { > + struct sprd_i2c *i2c_dev = dev_get_drvdata(pdev); > + > + i2c_lock_adapter(&i2c_dev->adap); > + i2c_dev->is_suspended = true; > + i2c_unlock_adapter(&i2c_dev->adap); > + > return pm_runtime_force_suspend(pdev); > } > > static int __maybe_unused sprd_i2c_resume_noirq(struct device *pdev) > { > + struct sprd_i2c *i2c_dev = dev_get_drvdata(pdev); > + > + i2c_lock_adapter(&i2c_dev->adap); > + i2c_dev->is_suspended = false; > + i2c_unlock_adapter(&i2c_dev->adap); > + > return pm_runtime_force_resume(pdev); > } > > -- regards, -grygorii