Automatic clock disabling on clk_put()

Hello,

On Tue, May 12, 2015 at 04:23:48PM -0700, Stephen Boyd wrote:

On 05/10/15 23:01, Sascha Hauer wrote:

quoted

Hi,

Since we now have per-user clks we could automatically disable clks on
clk_put() to make the drivers errors paths easier. AFAIR that was one
of the motivations to switch to per user clks. Is this just not yet
implemented or are there problems implementing this?

I don't recall that as being a motivation for per-user clks. The
documentation explicitly states:

 * Note: drivers must ensure that all clk_enable calls made on this
 * clock source are balanced by clk_disable calls prior to calling
 * this function.

so it seems that such a behavior would be an API change. Is it really

well, it's a compatible API change. So if you continue to use it as you
were obliged to do before, everything is fine. IMHO the introduction of
per-user clocks are a much bigger issue.

I'm not sure that auto disabling is a good idea[1], but at least giving a
warning should be possible.

that hard to call clk_disable_unprepare() on a clock at the end of an
error path? Maybe you could add a devm_clk_get_prepare_enable() that
does what you want and then call clk_disable_unprepare on the exit path?

You mean clk_disable_unprepare is called in the same function that calls
clk_put I assume such that you don't have to do anything in the exit
path.

Best regards
Uwe

[1] mainly because I didn't think about it
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Pengutronix e.K.                           | Uwe Kleine-K?nig            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |