[RFC 02/11] i2c: add quirk checks to core
sergei.shtylyov at cogentembedded.com
Fri Jan 9 13:05:07 PST 2015
On 01/09/2015 11:45 PM, Wolfram Sang wrote:
>>> Let the core do the checks if HW quirks prevent a transfer. Saves code
>> >from drivers and adds consistency.
>>> Signed-off-by: Wolfram Sang <wsa at the-dreams.de>
>>> drivers/i2c/i2c-core.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>> 1 file changed, 53 insertions(+)
>>> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
>>> index 39d25a8cb1ad..7b10a19abf5b 100644
>>> --- a/drivers/i2c/i2c-core.c
>>> +++ b/drivers/i2c/i2c-core.c
>>> @@ -2063,6 +2063,56 @@ module_exit(i2c_exit);
>>> * ----------------------------------------------------
>>> +/* Check if val is exceeding the quirk IFF quirk is non 0 */
>>> +#define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk)))
>>> +static int i2c_quirk_error(struct i2c_adapter *adap, struct i2c_msg *msg, char *err_msg)
>>> + dev_err(&adap->dev, "quirk: %s (addr 0x%04x, size %u)\n", err_msg, msg->addr, msg->len);
>>> + return -EOPNOTSUPP;
>> Always returning the same value doesn't make much sense. Are you trying
>> to save space on the call sites?
> Please elaborate. I think it does. If a quirk matches, we report that we
> don't support this transfer.
OK, but what's the point of having this function return *int* if it always
returns the same value? AFAIU, you're trying to save the code space on the
call sites of this function by not having *return* -EOPNOTSUPP there each time?
>>> @@ -2080,6 +2130,9 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
>>> unsigned long orig_jiffies;
>>> int ret, try;
>>> + if (adap->quirks && i2c_check_for_quirks(adap, msgs, num))
>> So, you only check for non-zero result of this function? Perhaps it makes
>> sense to return true/false instead?
> Could be done, but what would be the advantage? A lot of functions
> return errno or 0.
It would have been OK if you were actually caring about the result, e.g.
returning it from __i2c_transfer(). Since you don't, IMO it would make more
sense to return true from i2c_check_for_quirks() (making it *bool*) iff it did
find/apply a quirk.
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