Subject: [PATCH-V2 08/12] i2c: pxa: enable/disable i2c module across msg xfer

From: [email-masked] (Vaibhav Hiremath)
Date: Fri, 03 Jul 2015 23:53:56 +0530

On Friday 03 July 2015 08:58 PM, Robert Jarzmik wrote:
> Vaibhav Hiremath <[email-masked]> writes:
>
>>   #define _IBMR(i2c)	((i2c)->reg_ibmr)
>> @@ -286,6 +287,22 @@ static void i2c_pxa_scream_blue_murder(struct pxa_i2c *i2c, const char *why)
>>   static void i2c_pxa_master_complete(struct pxa_i2c *i2c, int ret);
>>   static irqreturn_t i2c_pxa_handler(int this_irq, void *dev_id);
>>
>> +/* enable/disable i2c unit */
>> +static inline int i2c_pxa_is_enabled(struct pxa_i2c *i2c)
>> +{
>> +	return (readl(_ICR(i2c)) & ICR_IUE);
>> +}
>> +
>> +static inline void i2c_pxa_enable(struct pxa_i2c *i2c, bool enable)
>> +{
>> +	if (enable && !i2c_pxa_is_enabled(i2c)) {
>> +		writel(readl(_ICR(i2c)) | ICR_IUE, _ICR(i2c));
>> +		udelay(100);
>> +	} else {
>> +		writel(readl(_ICR(i2c)) & ~ICR_IUE, _ICR(i2c));
>> +	}
>> +}
>> +
>>   static inline int i2c_pxa_is_slavemode(struct pxa_i2c *i2c)
>>   {
>>   	return !(readl(_ICR(i2c)) & ICR_SCLE);
>> @@ -482,8 +499,7 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
>>   	i2c_pxa_set_slave(i2c, 0);
>>
>>   	/* enable unit */
>> -	writel(readl(_ICR(i2c)) | ICR_IUE, _ICR(i2c));
>> -	udelay(100);
>> +	i2c_pxa_enable(i2c, true);
>>   }
>>
>>
>> @@ -840,6 +856,9 @@ static int i2c_pxa_pio_xfer(struct i2c_adapter *adap,
>>   	struct pxa_i2c *i2c = adap->algo_data;
>>   	int ret, i;
>>
>> +	/* Enable i2c unit */
>> +	i2c_pxa_enable(i2c, true);
>> +
>>   	/* If the I2C controller is disabled we need to reset it
>>   	  (probably due to a suspend/resume destroying state). We do
>>   	  this here as we can then avoid worrying about resuming the
>> @@ -860,6 +879,11 @@ static int i2c_pxa_pio_xfer(struct i2c_adapter *adap,
>>   	ret = -EREMOTEIO;
>>    out:
>>   	i2c_pxa_set_slave(i2c, ret);
>> +
>> +	/* disable i2c unit */
>> +	if (i2c->disable_after_xfer)
>> +		i2c_pxa_enable(i2c, false);
>> +
>>   	return ret;
>>   }
>>
>> @@ -1075,6 +1099,9 @@ static int i2c_pxa_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num
>>   	struct pxa_i2c *i2c = adap->algo_data;
>>   	int ret, i;
>>
>> +	/* Enable i2c unit */
>> +	i2c_pxa_enable(i2c, true);
> Okay, what happens in master mode when we get there on the 2nd xfer :
>   - i2c is enabled AFAIU.
>   - as a consequence i2c_pxa_is_enabled() returns true
>   - as a consequence, i2c_pxa_enable() _disables_ the i2c, right ?
>   - as a consequence i2c is broken
>
> Is this correct, because if it is the patch needs a rework ?
>

Good catch :)

I will fix this in next version.

Thanks,
Vaibhav