[PATCH 2/2] clk: bcm2835: expose current divider, parent and mash via debugfs

Martin Sperl kernel at martin.sperl.org
Mon Feb 29 13:11:19 PST 2016

> On 29.02.2016, at 21:43, Eric Anholt <eric at anholt.net> wrote:
> kernel at martin.sperl.org writes:
>> From: Martin Sperl <kernel at martin.sperl.org>
>> For each clock expose the following values via debugfs:
>> * current_parent - the currently selected parent
>> * current_divi - the integer portion of the currently set divider
>> * current_divf - the fractional portion of the currently set divider
>> * current_frac - the current frac/mash settings for the divider
> current_parent can already be found through /debug/clk/clk_summary quite
> nicely I think.  If we wanted a per-clock parent file, that seems like
> something the core ought to be doing.
> current_frac is looking at a bit that doesn't exist for non-MASH clocks.
> divi/divf are OK, I guess, but don't seem particularly useful given the
> raw register output already.  A cooked floating point point divider
> debugfs entry would be nice, but I don't know if we can do that.

The reason I had those is because I wanted to allow people to
see quickly what is the parent clock and what is the used 
parent and divider…

While discussing with the PCM/I2s people they were always concerned
about those details - so I needed to provide them with a way to access
those things easily. And explaining to them the register format was -
for me - out of the question.

Especially the mapping of “id” to real parent was a bit of a pain.

What do you mean by cooked? Something like: "33+27/4096”?


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