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Commit 1e435256 authored by Olof Johansson's avatar Olof Johansson Committed by Mike Turquette
Browse files

clk: add clk_ignore_unused option to keep boot clocks on 



This is primarily useful when there's a driver that doesn't claim clocks
properly, but the bootloader leaves them on. It's not expected to be used
in normal cases, but for bringup and debug it's very useful to have the
option to not gate unclaimed clocks that are still on.

Signed-off-by: default avatarOlof Johansson <olof@lixom.net>
Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
[mturquette@linaro.org: fixed up trivial merge issue]
parent c700835b

Documentation/clk.txt

+11 −0
Original line number Original line Diff line number Diff line
@@ -231,3 +231,14 @@ To better enforce this policy, always follow this simple rule: any 
statically initialized clock data MUST be defined in a separate file

statically initialized clock data MUST be defined in a separate file

from the logic that implements its ops.  Basically separate the logic

from the logic that implements its ops.  Basically separate the logic

from the data and all is well.

from the data and all is well.



	Part 6 - Disabling clock gating of unused clocks



Sometimes during development it can be useful to be able to bypass the

default disabling of unused clocks. For example, if drivers aren't enabling

clocks properly but rely on them being on from the bootloader, bypassing

the disabling means that the driver will remain functional while the issues

are sorted out.



To bypass this disabling, include "clk_ignore_unused" in the bootargs to the

kernel.

Documentation/kernel-parameters.txt

+8 −0
Original line number Original line Diff line number Diff line
@@ -44,6 +44,7 @@ parameter is applicable: 
	AVR32	AVR32 architecture is enabled.

	AVR32	AVR32 architecture is enabled.

	AX25	Appropriate AX.25 support is enabled.

	AX25	Appropriate AX.25 support is enabled.

	BLACKFIN Blackfin architecture is enabled.

	BLACKFIN Blackfin architecture is enabled.

	CLK	Common clock infrastructure is enabled.

	DRM	Direct Rendering Management support is enabled.

	DRM	Direct Rendering Management support is enabled.

	DYNAMIC_DEBUG Build in debug messages and enable them at runtime

	DYNAMIC_DEBUG Build in debug messages and enable them at runtime

	EDD	BIOS Enhanced Disk Drive Services (EDD) is enabled

	EDD	BIOS Enhanced Disk Drive Services (EDD) is enabled
@@ -465,6 +466,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 




	cio_ignore=	[S390]

	cio_ignore=	[S390]

			See Documentation/s390/CommonIO for details.

			See Documentation/s390/CommonIO for details.

	clk_ignore_unused

			[CLK]

			Keep all clocks already enabled by bootloader on,

			even if no driver has claimed them. This is useful

			for debug and development, but should not be

			needed on a platform with proper driver support.

			For more information, see Documentation/clk.txt.





	clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.

	clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.

			[Deprecated]

			[Deprecated]

drivers/clk/clk.c

+13 −0
Original line number Original line Diff line number Diff line
@@ -499,10 +499,23 @@ static void clk_disable_unused_subtree(struct clk *clk) 
	return;

	return;

}

}





static bool clk_ignore_unused;

static int __init clk_ignore_unused_setup(char *__unused)

{

	clk_ignore_unused = true;

	return 1;

}

__setup("clk_ignore_unused", clk_ignore_unused_setup);



static int clk_disable_unused(void)

static int clk_disable_unused(void)

{

{

	struct clk *clk;

	struct clk *clk;





	if (clk_ignore_unused) {

		pr_warn("clk: Not disabling unused clocks\n");

		return 0;

	}



	clk_prepare_lock();

	clk_prepare_lock();





	hlist_for_each_entry(clk, &clk_root_list, child_node)

	hlist_for_each_entry(clk, &clk_root_list, child_node)