Re: [PATCH v10] i2c: virtio: add a virtio i2c frontend driver

Jie Deng
2021-03-24T01:18:59Z

On 2021/3/23 17:27, Arnd Bergmann wrote:
> On Tue, Mar 23, 2021 at 9:33 AM Jie Deng <jie.deng@intel.com> wrote:
>> On 2021/3/23 15:27, Viresh Kumar wrote:
>>
>>> On 23-03-21, 22:19, Jie Deng wrote:
>>>> +static int __maybe_unused virtio_i2c_freeze(struct virtio_device *vdev)
>>>> +{
>>>> + virtio_i2c_del_vqs(vdev);
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int __maybe_unused virtio_i2c_restore(struct virtio_device *vdev)
>>>> +{
>>>> + return virtio_i2c_setup_vqs(vdev->priv);
>>>> +}
>>> Sorry for not looking at this earlier, but shouldn't we enclose the above two
>>> within #ifdef CONFIG_PM_SLEEP instead and drop the __maybe_unused ?
>>
>> I remembered I was suggested to use "__maybe_unused" instead of "#ifdef".
>>
>> You may check this https://lore.kernel.org/patchwork/patch/732981/
>>
>> The reason may be something like that.
> I usually recommend the use of __maybe_unused for the suspend/resume
> callbacks for drivers that use SIMPLE_DEV_PM_OPS() or similar helpers
> that hide the exact conditions under which the functions get called.
>
> In this driver, there is an explicit #ifdef in the reference to the
> functions, so
> it would make sense to use the same #ifdef around the definition.
>
> A better question to ask is whether you could use the helpers instead,
> and drop the other #ifdef.
>
> Arnd

I didn't see the "struct virtio_driver" has a member "struct dev_pm_ops *pm"

It defines its own hooks (freeze and restore) though it includes "struct
device_driver"

which has a "struct dev_pm_ops *pm".

I just follow other virtio drivers to directly use the hooks defined in
"struct virtio_driver".

For this driver, Both __maybe_unused and #ifdef are OK to me.