Re: [PATCH 04/13] OMAP: Introduce dependent voltage domain support

[Kevin Hilman <khilman@ti.com>]

Vishwanath Sripathy <vishwanath.bs@ti.com> writes:

[...]

>> > diff --git a/arch/arm/mach-omap2/dvfs.c b/arch/arm/mach-
>> omap2/dvfs.c
>> > index cefc2be..c9d3894 100755
>> > --- a/arch/arm/mach-omap2/dvfs.c
>> > +++ b/arch/arm/mach-omap2/dvfs.c
>> > @@ -85,6 +85,7 @@ struct omap_vdd_dvfs_info {
>> >  	struct mutex scaling_mutex; /* dvfs mutex */
>> >  	struct voltagedomain *voltdm;
>> >  	struct list_head dev_list;
>> > +	struct device vdd_device;
>>
>> It's not clear what the usage of this device is for.
>>
>> It is never initialized, but seems to be used as a dummy device when
>> calcluating dependencies.   Needs clarification.
>
> This device is used for placing voltage request (omap_dvfs_add_vdd_user)
> when dealing with dependent vdds. Eg: while scaling MPU VDD, we also scale
> CORE VDD. So while placing voltage request for CORE VDD, this vdd_device
> of MPU is used as the requesting device so that this request is stored as
> a separate user.

I was able to follow how it was used, and why.   But it is still not
clear to the reader.

First, the device is never initialized, so it's essentially a dummy
device that remains initialized by default to all zeros.   So, any
attempt to use any device APIs (e.g. dev_name, etc.) on this will not
behave as expected.

Second, the reason for this device and the need for the request to be
stored as a separate user are not clear in the code and don't exist in
the comments.

Kevin