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

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 <>
Signed-off-by: default avatarMike Turquette <>
[ fixed up trivial merge issue]
parent c700835b
......@@ -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
from the logic that implements its ops. Basically separate the logic
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
......@@ -44,6 +44,7 @@ parameter is applicable:
AVR32 AVR32 architecture is enabled.
AX25 Appropriate AX.25 support is enabled.
BLACKFIN Blackfin architecture is enabled.
CLK Common clock infrastructure is enabled.
DRM Direct Rendering Management support is enabled.
DYNAMIC_DEBUG Build in debug messages and enable them at runtime
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]
See Documentation/s390/CommonIO for details.
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.
......@@ -499,10 +499,23 @@ static void clk_disable_unused_subtree(struct clk *clk)
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)
struct clk *clk;
if (clk_ignore_unused) {
pr_warn("clk: Not disabling unused clocks\n");
return 0;
hlist_for_each_entry(clk, &clk_root_list, child_node)
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