On Mon, 2018-09-03 at 01:17 +0000, Andy Tang wrote:

Hi Scott,

Please see my replay in line.

quoted

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[off-list ref]
Subject: Re: [PATCH 3/5] drivers: clk-qoriq: Add clockgen support for
lx2160a

On Fri, 2018-08-31 at 06:12 +0000, Andy Tang wrote:

quoted

We don't want to increase NUM_CMUX each time new soc with more

cmuxes added.

You don't want to have to make a trivial change each time you exceed a
limit that has yet to be exceeded once since NUM_CMUX was added?
This isn't ABI or in any other way hard to change.  It's right in the same
file
as the chip description you'd be adding.

And even if a chip did come along with 16 cmuxes, you'd then need to
increase the array to 17 to hold the -1 if you don't want to leave a
situation
like the
p4080 is in now, where a chip's cmux array could be broken by increasing
NUM_CMUX further.

[Andy] Adding buffer to a limitation number is always a good habit when
coding. We often forget to increase this value when
a new chip with more cmuxes added. 

"often"?  There has never been a new chip added with more cmuxes than p4080's
8, and if one does come along and you forget, the compiler should complain
about exceeding the array length with a static initializer.  This isn't like
an array that is filled with a runtime-determined length.

Like this patch, we didn't increase this value at first. We spent a lot of
time finding out that NUM_CMUX needs to be increased too.

Are you talking about some other chip that you haven't sent a patch for yet? 
Or is the cmux array for this chip wrong?  What specifically did you see
happen "at first"?

It is a personal preference how to set this value. I think it is better to
increase it to 16, not NUM_CMUX+1 as long as we fix the P4080 issue
even though it is a trivial change. And I agree the description needs to be
updated.

I'm not the clock maintainer, so it's not up to me, but I don't see the point
in setting it to an arbitrary number, and I do not agree that increasing
NUM_CMUX is a suitable replacement for NUM_CMUX+1 in cmux_to_group[], as that
array should be one larger than cmux[] in order to allow every chip to have a
-1 terminator.  In any case, any change to NUM_CMUX should be a separate patch
because it's not required for lx2160a support (assuming lx2160a was correctly
described by this patch).

-Scott