Re: [PATCH 4/4] i2c: qup: Add command-line parameter to override SCL frequency

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Hi Austin,

On 4/25/2018 8:37 PM, Christ, Austin wrote:
> Hey Sricharan,
> 
> On 4/25/2018 4:57 AM, Sricharan R wrote:
>>
>>
>> On 4/25/2018 2:51 AM, Austin Christ wrote:
>>> Add a module parameter to override SCL frequency provided by firmware.
>>> This can be useful when testing spec compliance for I2C modes or when
>>> debugging issues across multiple operating frequencies.
>>>
>>> Signed-off-by: Austin Christ <austinwc@xxxxxxxxxxxxxx>
>>> ---
>>>   drivers/i2c/busses/i2c-qup.c | 19 ++++++++++++++-----
>>>   1 file changed, 14 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
>>> index f87f29f..da4cc57 100644
>>> --- a/drivers/i2c/busses/i2c-qup.c
>>> +++ b/drivers/i2c/busses/i2c-qup.c
>>> @@ -155,6 +155,10 @@
>>>   /* TAG length for DATA READ in RX FIFO  */
>>>   #define READ_RX_TAGS_LEN        2
>>>   +static unsigned int scl_freq;
>>> +module_param_named(scl_freq, scl_freq, uint, 0444);
>>
>> Instead of hard coding the permission constants, macro can be used.
>>
>> Otherwise,
>>
>>   Reviewed-by: Sricharan R <sricharan@xxxxxxxxxxxxxx>
>>
>> Regards,
>>   Sricharan
>>
> 
> Ok I'll switch it. I originally switched to 0444 based on a recommendation from checkpatch.
>>

 hmm, guess i was wrong there. sorry. Better to stick to octal then as you already have.

Regards,
 Sricharan


>>> +MODULE_PARM_DESC(scl_freq, "SCL frequency override");
>>> +
>>>   /*
>>>    * count: no of blocks
>>>    * pos: current block number
>>> @@ -1682,11 +1686,16 @@ static int qup_i2c_probe(struct platform_device *pdev)
>>>       init_completion(&qup->xfer);
>>>       platform_set_drvdata(pdev, qup);
>>>   -    ret = device_property_read_u32(qup->dev, "clock-frequency", &clk_freq);
>>> -    if (ret) {
>>> -        dev_notice(qup->dev, "using default clock-frequency %d",
>>> -            DEFAULT_CLK_FREQ);
>>> -    }
>>> +    if (scl_freq) {
>>> +        dev_notice(qup->dev, "Using override frequency of %u\n", scl_freq);
>>> +        clk_freq = scl_freq;
>>> +    } else {
>>> +        ret = device_property_read_u32(qup->dev, "clock-frequency", &clk_freq);
>>> +        if (ret) {
>>> +            dev_notice(qup->dev, "using default clock-frequency %d",
>>> +                DEFAULT_CLK_FREQ);
>>> +        }
>>> +    }
>>>         if (of_device_is_compatible(pdev->dev.of_node, "qcom,i2c-qup-v1.1.1")) {
>>>           qup->adap.algo = &qup_i2c_algo;
>>>
>>
> 

-- 
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