RFC PATCH 2.6 sysfs names: fscher: change div to ripple

Grant Coady grant_lkml at dodo.com.au
Wed Apr 27 01:25:04 CEST 2005

On Tue, 26 Apr 2005 14:49:47 -0700, Philip Pokorny <ppokorny at penguincomputing.com> wrote:

>So a ripple counter is the equivalent to a fan divisor and therefore I 
>would recommend *not* to apply this patch to rename it.  Keep the 
>original fan_div name.

Jean Delvare tells me the thing is different, my request for a tester 
has gone unanswered thus far, if you have access to one of these chips 
the test is simple: if changing fan_ripple/fan_div doubles or halves 
the fan speed reading, then fan_ripple != fan_div.  That easy!

Until somebody provides the answer to that simple test I am assuming 
fan_ripple != fan_div.

>If fscpos has a fan_ripple accessor, then *it* should be changed to 
>fan_div, not the other way round.

Disagree, if you have access to these chips, please perform the test 
and let me know result, then we can say the datasheet is a poor 
translation.  (pulses <=> ripples struck me as strange translation).

The datasheet _is clear_ on defining ripples as 2, 4 or 8 per fan 
revolution, whereas datasheets for chips with 22.5kHz fan clock 
divided before -> gated counter _always_ spec the fan as two pulses 
per revolution.

Having the same name for a fundamentally different function would 
not be useful.

The current different names for the same function is plainly wrong.

The available evidence to me points to a difference in function, 
requiring a name change.  If you can perform the test confirming 
this issue then we know the correct name to use.

(fanX_pulses_per_rev) --> user-space should have this too, to scale 
fan speed when they have other than two pulses per rev fans.


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