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SubjectRe: [RESEND PATCH v3 3/5] i2c: i2c-stm32f7: add driver
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On 09/13/2017 11:26 PM, Wolfram Sang wrote:
> Hi,
>
> thanks for this driver!
>
>> +/**
>> + * struct stm32f7_i2c_spec - private i2c specification timing
>> + * @rate: I2C bus speed (Hz)
>> + * @rate_min: 80% of I2C bus speed (Hz)
>> + * @rate_max: 120% of I2C bus speed (Hz)
>
> You would generate a clock which is higher than the requested one?
> This is highly unusual. Any special reason?

Well. I allow the clock to be higher than expected.
Looking at I2C spec again it turns out the mode specifies the max: no overshoot
of the clock. I will lock max to 100% then.
Will be fixed

>
>> + * @fall_max: Max fall time of both SDA and SCL signals (ns)
>> + * @rise_max: Max rise time of both SDA and SCL signals (ns)
>> + * @hddat_min: Min data hold time (ns)
>> + * @vddat_max: Max data valid time (ns)
>> + * @sudat_min: Min data setup time (ns)
>> + * @l_min: Min low period of the SCL clock (ns)
>> + * @h_min: Min high period of the SCL clock (ns)
>> + */
>> +static struct stm32f7_i2c_spec i2c_specs[] = {
>> + [STM32_I2C_SPEED_STANDARD] = {
>> + .rate = 100000,
>> + .rate_min = 8000,
>
> This is not 80%. Typo?

Yep. This is a typo

>
>> + .rate_max = 120000,
>> + .fall_max = 300,
>> + .rise_max = 1000,
>> + .hddat_min = 0,
>> + .vddat_max = 3450,
>> + .sudat_min = 250,
>> + .l_min = 4700,
>> + .h_min = 4000,
>> + },
>
> ...
>
>> + /*
>> + * Among Prescaler possibilities discovered above figures out SCL Low
>> + * and High Period. Provided:
>> + * - SCL Low Period has to be higher than Low Period of tehs SCL Clock
>
> tehs?

Oops.

>
>> + * defined by I2C Specification. I2C Clock has to be lower than
>> + * (SCL Low Period - Analog/Digital filters) / 4.
>> + * - SCL High Period has to be lower than High Period of the SCL Clock
>> + * defined by I2C Specification
>> + * - I2C Clock has to be lower than SCL High Period
>> + */
>
> ...
>
>> + /* NACK received */
>> + if (status & STM32F7_I2C_ISR_NACKF) {
>> + dev_dbg(i2c_dev->dev, "<%s>: Receive NACK\n", __func__);
>> + writel_relaxed(STM32F7_I2C_ICR_NACKCF, base + STM32F7_I2C_ICR);
>> + f7_msg->result = -EBADE;
>
> -ENXIO (see Documentation/i2c/fault-codes)

OK

>
> ...
>
>> + timeout = wait_for_completion_timeout(&i2c_dev->complete,
>> + i2c_dev->adap.timeout);
>> + ret = f7_msg->result;
>> +
>> + if (!timeout) {
>> + dev_dbg(i2c_dev->dev, "Access to slave 0x%x timed out\n",
>> + i2c_dev->msg->addr);
>> + ret = -ETIMEDOUT;
>> + }
>
> Could you rename the variable to time_left? It looks strange, basically:
>
> if (!timeout)
> return -ETIMEDOUT
>

okay

> ...
>
>> + adap->retries = 0;
>
> Why no retries when you check for arbitration lost?
>
>> + adap->algo = &stm32f7_i2c_algo;
>> + adap->dev.parent = &pdev->dev;
>> + adap->dev.of_node = pdev->dev.of_node;
>> +
>> + init_completion(&i2c_dev->complete);
>> +
>> + ret = i2c_add_adapter(adap);
>> + if (ret) {
>> + dev_err(&pdev->dev, "Failed to add adapter\n");
>
> Please remove, the core will print info when adding fails.
>

I will

>
> Rest looks good!

Great !

>
> Thanks,
>
> Wolfram
>

Thanks

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