Hi Rafael,

On 21/07/15 15:34, Rafael J. Wysocki wrote:

Hi Sudeep,

On Tue, Jul 21, 2015 at 11:23 AM, Sudeep Holla [off-list ref] wrote:

quoted

On 20/07/15 23:04, Rafael J. Wysocki wrote:

quoted

On Monday, July 20, 2015 03:22:37 PM Sudeep Holla wrote:

quoted

On 09/07/15 19:04, Ashwin Chaugule wrote:

quoted

CPPC is the first client to make use of the PCC Mailbox channel. So
enable it only when CPPC is also enabled.

This sounds like a reverse dependency to me. So if there's some client
unrelated to CPPC using PCC, CPPC_LIB needs to be selected to enable PCC
?

No.  The other client will need to select PCC too.

Yes the PCC users/clients selecting PCC is fine and that's already
done(i.e. ACPI_CPPC_LIB selects PCC). I still don't understand the need
for this change, also how will other clients possibly select PCC which
now depends on CPPC_LIB ? e.g. if we have

config ACPI_XYZ_LIB
         select PCC

config ACPI_XYZ
         select ACPI_XYZ_LIB

Won't this shout warning: (ACPI_XYZ_LIB && ACPI_CPPC_LIB) selects PCC
which has unmet direct dependencies (MAILBOX && ACPI && ACPI_CPPC_LIB)
if ACPI_CPPC_LIB is not selected ?

That depends on the "depends on" clauses used.  Selecting itself
doesn't cause any dependencies to appear.

Agreed and I am absolutely fine with that. But if you look at this 
patch, it does

config PCC
	bool "Platform Communication Channel Driver"
	depends on ACPI && ACPI_CPPC_LIB

I am fine with ACPI_CPPC_LIB selecting PCC which is already done in
earlier patch. I am against making PCC depend on ACPI_CPPC_LIB.

Lets assume it's fine to do that. Now if another feature XYZ as in my
example say on x86 selects PCC then you will *get warnings* as we will
not able to select PCC without selecting ACPI_CPPC_LIB after this patch
and x86 will never select ACPI_CPPC_LIB. I did test something like my
XYZ example and it did trigger the warning as I suspected.

I am sorry either I am missing to understand again or unable to express
the problem here :(

quoted

OK, for now we enable ACPI_CPPC_LIB on ARM64 and not on x86. When x86
has a PCC client how will that select PCC without ACPI_CPPC_LIB. Sorry
if I am missing to understand something.

Presumably, the new feature will have a Kconfig option associated with
it and it will do "select PCC" too.

As I say I am fine with that and no arguments there.

Regards,
Sudeep