Hello Brian,
On 06/20/2016 02:10 PM, Brian Norris wrote:
> Hi,
>
> On Mon, Jun 20, 2016 at 10:44:55AM -0700, Brian Norris wrote:
>> On Mon, Jun 20, 2016 at 09:46:57AM -0400, Javier Martinez Canillas wrote:
>>> On 06/18/2016 01:09 PM, Guenter Roeck wrote:
>>>> On 06/17/2016 06:08 PM, Brian Norris wrote:
>>>>> How do you propose we do that? Do all of the following become EINVAL?
>>>>>
>>>
>>> Yes, I would just do that.
>>>
>>> The idea of this helper is to remove duplicated code and AFAICT what most EC
>>> drivers do is something similar to the following:
>>>
>>> ret = cros_ec_cmd_xfer(ec, msg);
>>> if (ret < 0)
>>> return ret;
>>>
>>> if (msg->result != EC_RES_SUCCESS) {
>>> dev_dbg(ec->dev, "EC result %d\n", msg->result);
>>> return -EINVAL;
>>> }
>>>
>>> So in practice what most drivers really care is if the result was successful
>>> or not, I don't see specific EC error handling in the EC drivers. The real
>>> EC error code is still in the message anyways so drivers that do cares about
>>> the real EC error can look at msg->result instead.
> [...]
>>>>> EC_RES_INVALID_COMMAND
>>>>
>>>> -EOPNOTSUPP
>>>>
>>>>> EC_RES_INVALID_PARAM
>>>>
>>>> -EINVAL or -EBADMSG
>>>>
>>>>> EC_RES_INVALID_VERSION
>>>>
>>>> -EPROTO or -EBADR or -EBADE or -EBADRQC or -EPROTOOPT
>>>>
>>>>> EC_RES_INVALID_HEADER
>>>>
>>>> -EPROTO or -EBADR or -EBADE
>>>>
>>>> Doesn't look that bad to me. Also, the raw error could still be logged,
>>>> for example with dev_dbg().
>>>>
>>>
>>> Yes, I think that adding a dev_dbg() with the real EC error code should
>>> be enough, that's basically what drivers do since they can't propagate
>>> the EC error to higher layers anyways.
>>
>> I'll take a look at adding an error code translation table when I get a
>> chance. Hopefully that doesn't delay the others who are planning to use
>> this API shortly...
>
> Actually, I had some second thoughts, and others brought similar
> concerns up to me:
>
> What do we really win by doing the translation? It'll be difficult to do
> a 1:1 translation, and any time the EC adds additional error types,
> we'll have to update the translation. What's more, AFAICT, no one will
> really be looking at the translated error codes now, and will just be
> blindly passing them on. So maybe it makes more sense to just pick a
> single error code and pass that on instead. Possibly just -EPROTO (or
> nominate your favorite) for all EC error results, and if someone cares,
I think I didn't make clear in my previous email but yes, I also think
that a translate table for errors is not a good idea and that just a
single -EINVAL (or another error if is more suitable for all EC errors)
will be enough. I say -EINVAL because that's what you first mentioned
in a previous email and that's what most EC clients drivers are using.
I do believe that EC specific errors shouldn't be returned in a Linux
function though for the reasons I explained before.
> they decode msg->result in their driver, or check the dev_dbg() log?
>
And yes, I also think that a dev_dbg() is a good idea (the more data
we have about an error, the better) and as mentioned the EC error can
always be found in the EC message result field.
> Brian
>
Best regards,
--
Javier Martinez Canillas
Open Source Group
Samsung Research America
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