Re: [PATCH v2] HID: cp2112: support large i2c transfers in hid-cp2112

[Ellen Wang <ellen@cumulusnetworks.com>]

On 07/09/2015 01:07 AM, Vaibhav Hiremath wrote:
> ...
>>>> +        count += ret;
>>>> +        if (count > msgs->len) {
>>>> +            /*
>>>> +             * The hardware returned too much data.
>>>> +             * This is mostly harmless because cp2112_read()
>>>> +             * has a limit check so didn't overrun our
>>>> +             * buffer.  Nevertheless, we return an error
>>>> +             * because something is seriously wrong and
>>>> +             * it shouldn't go unnoticed.
>>>> +             */
>>>> +            hid_err(hdev, "long read: %d > %zd\n",
>>>> +                ret, msgs->len - count + ret);
>>>
>>> You may want to take another look here.
>>> 'ret' will be either,
>>>
>>>      - ret = msgs->len
>>>          Not applicable
>>>      - ret > msgs->len
>>>          (count > msgs->len) will happen in one single
>>>          iteration, and will
>>>      - ret < msgs->len
>>>          (count > msgs->len) will happen in multiple iterations
>>>          where count keeps incrementing based on ret
>>>
>>> In the 2 scenarios above, I believe you would want to show,
>>>
>>>      actual read bytes > requested read bytes
>>>
>>>
>>> Am I missing something here?
>>
>> (count > msgs->len) should never happen, so there's really no predicting
>> it.  Or do you mean something else?
>>
>
> I meant the message which you are printing above seems wrong to me.

It does print the size of the read request.  I guess I could have 
written it as msgs->len - (count - ret).

Or I'm still missing what you mean.