linux-kernel - Re: [PATCH v2 6/6] i2c: i2c-stm32f7: Implement I2C recovery mechanism

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Message-ID: <ad11f5a5-4552-eb4a-7d7f-e0966bc340ea@st.com>
Date:   Mon, 26 Mar 2018 10:21:19 +0200
From:   Pierre Yves MORDRET <pierre-yves.mordret@...com>
To:     Wolfram Sang <wsa@...-dreams.de>
CC:     Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        <linux-i2c@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 6/6] i2c: i2c-stm32f7: Implement I2C recovery mechanism



On 03/24/2018 11:56 PM, Wolfram Sang wrote:
> On Wed, Mar 21, 2018 at 05:49:00PM +0100, Pierre-Yves MORDRET wrote:
>> Feature prevents I2C lock-ups. Mechanism resets I2C state machine
>> and releases SCL/SDA signals but preserves I2C registers.
>>
>> Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@...com>
>> ---
>>   Version history:
>>     v1:
>>        * Initial
>>     v2:
>>        * Don't use i2c engine recovery mechanism since driver
>>          procedure only recover master and not the slave.
> 
> s/recovery/release/ throughout the patch, please. Recovery is really
> something else. Also, I think the dev_info's are too noisy in the log
> files. I'd think the whole driver could be lifted from quite some
> logging...
> 

ok. will do.
Do you have example of info's that we should get rid of ?

>> ---
>> ---
>>  drivers/i2c/busses/i2c-stm32f7.c | 27 ++++++++++++++++++++++++---
>>  1 file changed, 24 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
>> index 91f73e0..9a9c469 100644
>> --- a/drivers/i2c/busses/i2c-stm32f7.c
>> +++ b/drivers/i2c/busses/i2c-stm32f7.c
>> @@ -718,6 +718,20 @@ static void stm32f7_i2c_smbus_reload(struct stm32f7_i2c_dev *i2c_dev)
>>  	writel_relaxed(cr2, i2c_dev->base + STM32F7_I2C_CR2);
>>  }
>>  
>> +static int stm32f7_i2c_recover_bus(struct i2c_adapter *i2c_adap)
>> +{
>> +	struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
>> +
>> +	dev_info(i2c_dev->dev, "Trying to recover bus\n");
>> +
>> +	stm32f7_i2c_clr_bits(i2c_dev->base + STM32F7_I2C_CR1,
>> +			     STM32F7_I2C_CR1_PE);
>> +
>> +	stm32f7_i2c_hw_config(i2c_dev);
>> +
>> +	return 0;
>> +}
>> +
>>  static int stm32f7_i2c_wait_free_bus(struct stm32f7_i2c_dev *i2c_dev)
>>  {
>>  	u32 status;
>> @@ -727,12 +741,18 @@ static int stm32f7_i2c_wait_free_bus(struct stm32f7_i2c_dev *i2c_dev)
>>  					 status,
>>  					 !(status & STM32F7_I2C_ISR_BUSY),
>>  					 10, 1000);
>> +	if (!ret)
>> +		return 0;
>> +
>> +	dev_info(i2c_dev->dev, "bus busy\n");
>> +
>> +	ret = stm32f7_i2c_recover_bus(&i2c_dev->adap);
>>  	if (ret) {
>> -		dev_dbg(i2c_dev->dev, "bus busy\n");
>> -		ret = -EBUSY;
>> +		dev_err(i2c_dev->dev, "Failed to recover the bus (%d)\n", ret);
>> +		return ret;
>>  	}
>>  
>> -	return ret;
>> +	return -EBUSY;
>>  }
>>  
>>  static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
>> @@ -1474,6 +1494,7 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
>>  	if (status & STM32F7_I2C_ISR_BERR) {
>>  		dev_err(dev, "<%s>: Bus error\n", __func__);
>>  		writel_relaxed(STM32F7_I2C_ICR_BERRCF, base + STM32F7_I2C_ICR);
>> +		stm32f7_i2c_recover_bus(&i2c_dev->adap);
>>  		f7_msg->result = -EIO;
>>  	}
>>  
>> -- 
>> 2.7.4
>>