* [PATCH] i2c: core: add device-managed version of i2c_new_dummy
@ 2017-08-21 18:24 Heiner Kallweit
2017-08-21 18:42 ` Peter Rosin
0 siblings, 1 reply; 5+ messages in thread
From: Heiner Kallweit @ 2017-08-21 18:24 UTC (permalink / raw)
To: Wolfram Sang; +Cc: linux-i2c@vger.kernel.org
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@gmail.com>
---
drivers/i2c/i2c-core-base.c | 29 +++++++++++++++++++++++++++++
include/linux/i2c.h | 3 +++
2 files changed, 32 insertions(+)
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 */
+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;
+
+ 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,
--
2.14.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] i2c: core: add device-managed version of i2c_new_dummy
2017-08-21 18:24 [PATCH] i2c: core: add device-managed version of i2c_new_dummy Heiner Kallweit
@ 2017-08-21 18:42 ` Peter Rosin
2017-08-21 19:56 ` Heiner Kallweit
0 siblings, 1 reply; 5+ messages in thread
From: Peter Rosin @ 2017-08-21 18:42 UTC (permalink / raw)
To: Heiner Kallweit, Wolfram Sang; +Cc: linux-i2c@vger.kernel.org
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@gmail.com>
> ---
> 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
> 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...
> +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?
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,
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] i2c: core: add device-managed version of i2c_new_dummy
2017-08-21 18:42 ` Peter Rosin
@ 2017-08-21 19:56 ` Heiner Kallweit
2017-08-21 21:28 ` Peter Rosin
0 siblings, 1 reply; 5+ messages in thread
From: Heiner Kallweit @ 2017-08-21 19:56 UTC (permalink / raw)
To: Peter Rosin, Wolfram Sang; +Cc: linux-i2c@vger.kernel.org
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@gmail.com>
>> ---
>> 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,
>>
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] i2c: core: add device-managed version of i2c_new_dummy
2017-08-21 19:56 ` Heiner Kallweit
@ 2017-08-21 21:28 ` Peter Rosin
2017-08-22 5:39 ` Heiner Kallweit
0 siblings, 1 reply; 5+ messages in thread
From: Peter Rosin @ 2017-08-21 21:28 UTC (permalink / raw)
To: Heiner Kallweit, Wolfram Sang; +Cc: linux-i2c@vger.kernel.org
On 2017-08-21 21:56, Heiner Kallweit wrote:
> 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@gmail.com>
>>> ---
>>> 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.
Yes and no.
Yes, it is ambitious, but the right thing to do in the end. And
it is mechanical, so it is not really hard. But I already said that
it might not be worth it at this point...
No, we do not have to follow the return value convention from
i2c_new_dummy in devm_i2c_new_dummy. What I meant below was that
for the time being devm_i2c_new_dummy can return ERR_PTR(-Ewhatever)
when i2c_new_dummy returns NULL. Then, when most/all i2c_new_dummy
users have been converted over to devm_i2c_new_dummy (which might
take a while) it will be less daunting to convert i2c_new_dummy to
not return a plain old boring NULL on failure. And then it will be
really easy to change devm_i2c_new_dummy to propagate that value w/o
causing massive churn in all callers at once.
> 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.
It would probably be good to target that question with an audience
a bit wider than the i2c list. Not sure where exactly it fits best
though?
Cheers,
peda
>> 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,
>>>
>>
>>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] i2c: core: add device-managed version of i2c_new_dummy
2017-08-21 21:28 ` Peter Rosin
@ 2017-08-22 5:39 ` Heiner Kallweit
0 siblings, 0 replies; 5+ messages in thread
From: Heiner Kallweit @ 2017-08-22 5:39 UTC (permalink / raw)
To: Peter Rosin, Wolfram Sang; +Cc: linux-i2c@vger.kernel.org
Am 21.08.2017 um 23:28 schrieb Peter Rosin:
> On 2017-08-21 21:56, Heiner Kallweit wrote:
>> 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@gmail.com>
>>>> ---
>>>> 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.
>
> Yes and no.
>
> Yes, it is ambitious, but the right thing to do in the end. And
> it is mechanical, so it is not really hard. But I already said that
> it might not be worth it at this point...
>
> No, we do not have to follow the return value convention from
> i2c_new_dummy in devm_i2c_new_dummy. What I meant below was that
> for the time being devm_i2c_new_dummy can return ERR_PTR(-Ewhatever)
> when i2c_new_dummy returns NULL. Then, when most/all i2c_new_dummy
> users have been converted over to devm_i2c_new_dummy (which might
> take a while) it will be less daunting to convert i2c_new_dummy to
> not return a plain old boring NULL on failure. And then it will be
> really easy to change devm_i2c_new_dummy to propagate that value w/o
> causing massive churn in all callers at once.
>
I see, yes this would make sense IMHO.
>> 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.
>
> It would probably be good to target that question with an audience
> a bit wider than the i2c list. Not sure where exactly it fits best
> though?
>
I think for now I will skip this as there are few users of
i2c_new_dummy using it with the i2c client being provided by a
parent device. Example: drivers/rtc/rtc-s5m.c
Rgds, Heiner
> Cheers,
> peda
>
>>> 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,
>>>>
>>>
>>>
>>
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
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2017-08-21 18:24 [PATCH] i2c: core: add device-managed version of i2c_new_dummy Heiner Kallweit
2017-08-21 18:42 ` Peter Rosin
2017-08-21 19:56 ` Heiner Kallweit
2017-08-21 21:28 ` Peter Rosin
2017-08-22 5:39 ` Heiner Kallweit
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