From: Russell King <rmk@dyn-67.arm.linux.org.uk>
Date: Tue, 24 Feb 2009 12:46:31 +0000 (+0000)
Subject: [ARM] omap: clk_set_parent: deny changing parent if clock is enabled
X-Git-Tag: v2.6.30-rc1~636^2~20^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4da3782151300237db3abe070f716922889252e0;p=pandora-kernel.git

[ARM] omap: clk_set_parent: deny changing parent if clock is enabled

Richard Woodruff writes:
| The historic usage of this has been against single use leaf clocks
| (1st instance of gptimer).  When it was used it did:
|       clk_get()
|       clk_set_parent()
|       clk_enable()
|
| This usage was ok for that. Use on a disabled clock is needed.
|
| If there are multiple users on the clock or it is enabled there are
| problems.
|
| The call can still be unfriendly if 2 different drivers are using the
| clock with their own clock get/enable. It might be the function should
| return an error if usecount != 0 to stop surprises.  It is all around
| better if the parenting is done when the clock is off.

This is a good reason to ensure that the clock is not enabled when
clk_set_parent() is called.

Acked-by: Richard Woodruff <r-woodruff2@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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