Am 21.08.2017 um 20:42 schrieb Peter Rosin:
> Hi!
>
> On 2017-08-21 20:24, Heiner Kallweit wrote:
>> i2c_new_dummy is typically called from the probe function of the
>> driver for the primary i2c client. It requires calls to
>> i2c_unregister_device in the error path of the probe function and
>> in the remove function.
>> This can be simplified by introducing a device-managed version.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
>> ---
>> drivers/i2c/i2c-core-base.c | 29 +++++++++++++++++++++++++++++
>> include/linux/i2c.h | 3 +++
>> 2 files changed, 32 insertions(+)
>
> You need to update Documentation/driver-model/devres.txt
>
Right, thanks for the hint.
>> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
>> index 12822a4b..7eb48328 100644
>> --- a/drivers/i2c/i2c-core-base.c
>> +++ b/drivers/i2c/i2c-core-base.c
>> @@ -868,6 +868,35 @@ struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
>> }
>> EXPORT_SYMBOL_GPL(i2c_new_dummy);
>>
>> +static void devm_i2c_release_dummy(struct device *dev, void *res)
>> +{
>> + i2c_unregister_device(*(struct i2c_client **)res);
>> +}
>> +
>> +/* managed version of i2c_new_dummy */
>
> A kernel-doc comment is preferred for public functions. Especially new
> functions...
>
OK
>> +struct i2c_client *devm_i2c_new_dummy(struct device *dev,
>> + struct i2c_adapter *adapter,
>> + u16 address)
>> +{
>> + struct i2c_client *ret, **dr;
>> +
>> + dr = devres_alloc(devm_i2c_release_dummy, sizeof(*dr), GFP_KERNEL);
>> + if (!dr)
>> + return NULL;
>
> Would it not be splendid if you returned an error pointer
> instead, preferably you should also change the i2c_new_dummy
> interface (don't forget to update callers) to return such a
> thing instead of NULL on error so that -EBUSY etc is
> propagated? But there are a few dozen callers, I don't know
> if it's worth it at this point?
>
i2c_new_dummy does little more than calling i2c_new_device
which returns NULL in case of an error. So we would have to
change i2c_new_device too. This may be a little too ambitious.
When talking about changing the interface:
devm_i2c_new_dummy usually will be called with parameters
dev = &client->dev and
adapter = client->adapter
So we could change and simplify it to
struct i2c_client *devm_i2c_new_dummy(struct i2c_client *client, u16 address)
However maintainers usually insist on first parameter of a devm_
function has to be a struct device *, although there are existing
devm_ functions like devm_regmap_init_i2c not following this rule.
I'd appreciate feedback whether it would be acceptable in our case.
> Anyway, if we do it right for the managed function from the
> start, that count of i2c_new_dummy callers might get more
> manageable in the future?
>
> Cheers,
> peda
>
>> +
>> + ret = i2c_new_dummy(adapter, address);
>> + if (!ret) {
>> + devres_free(dr);
>> + return NULL;
>> + }
>> +
>> + *dr = ret;
>> + devres_add(dev, dr);
>> +
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(devm_i2c_new_dummy);
>> +
>> /**
>> * i2c_new_secondary_device - Helper to get the instantiated secondary address
>> * and create the associated device
>> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
>> index d501d395..d0c091e6 100644
>> --- a/include/linux/i2c.h
>> +++ b/include/linux/i2c.h
>> @@ -381,6 +381,9 @@ extern int i2c_probe_func_quick_read(struct i2c_adapter *, unsigned short addr);
>> extern struct i2c_client *
>> i2c_new_dummy(struct i2c_adapter *adap, u16 address);
>>
>> +extern struct i2c_client *
>> +devm_i2c_new_dummy(struct device *dev, struct i2c_adapter *adap, u16 address);
>> +
>> extern struct i2c_client *
>> i2c_new_secondary_device(struct i2c_client *client,
>> const char *name,
>>
>
>
