| Message ID | 20221117105829.256717-1-bmasney@redhat.com (mailing list archive) |
|---|---|
| State | Rejected, archived |
| Headers | show |
| Series | clk: add debug message showing which unused clocks are disabled on boot | expand |
Quoting Brian Masney (2022-11-17 02:58:29) > The clk framework on bootup will automatically disable all unused clocks > on bootup unless the clk_ignore_unused kernel parameter is present. > Let's add a basic debugging log statement here that shows which clocks > are disabled. There is already tracepoint present here as well, but > there's nothing like a simple, good ol' fashioned printk for simplicity. > > Signed-off-by: Brian Masney <bmasney@redhat.com> > --- I'd like to see a documentation update instead that covers how to enable the tracepoint on the kernel commandline and have it print to the serial console.
On Wed, Mar 29, 2023 at 02:49:50PM -0700, Stephen Boyd wrote: > Quoting Brian Masney (2022-11-17 02:58:29) > > The clk framework on bootup will automatically disable all unused clocks > > on bootup unless the clk_ignore_unused kernel parameter is present. > > Let's add a basic debugging log statement here that shows which clocks > > are disabled. There is already tracepoint present here as well, but > > there's nothing like a simple, good ol' fashioned printk for simplicity. > > > > Signed-off-by: Brian Masney <bmasney@redhat.com> > > --- > > I'd like to see a documentation update instead that covers how to enable > the tracepoint on the kernel commandline and have it print to the serial > console. Sure, I can do that. I see there's a section 'Disabling clock gating of unused clocks' in Documentation/driver-api/clk.rst where I think this would be appropriate. Brian
On Thu, Mar 30, 2023 at 10:05:37AM -0400, Brian Masney wrote: > On Wed, Mar 29, 2023 at 02:49:50PM -0700, Stephen Boyd wrote: > > Quoting Brian Masney (2022-11-17 02:58:29) > > > The clk framework on bootup will automatically disable all unused clocks > > > on bootup unless the clk_ignore_unused kernel parameter is present. > > > Let's add a basic debugging log statement here that shows which clocks > > > are disabled. There is already tracepoint present here as well, but > > > there's nothing like a simple, good ol' fashioned printk for simplicity. > > > > > > Signed-off-by: Brian Masney <bmasney@redhat.com> > > > --- > > > > I'd like to see a documentation update instead that covers how to enable > > the tracepoint on the kernel commandline and have it print to the serial > > console. > > Sure, I can do that. I see there's a section 'Disabling clock gating of > unused clocks' in Documentation/driver-api/clk.rst where I think this > would be appropriate. Just to close out this thread, I submitted a patch to the docs tree. https://lore.kernel.org/lkml/20230411192153.289688-1-bmasney@redhat.com/T/#u Brian
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 57b83665e5c3..ddf5a48e72b6 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1352,6 +1352,7 @@ static void __init clk_disable_unused_subtree(struct clk_core *core) * back to .disable */ if (clk_core_is_enabled(core)) { + dev_dbg(core->dev, "Powering off unused clock %s\n", core->name); trace_clk_disable(core); if (core->ops->disable_unused) core->ops->disable_unused(core->hw);
The clk framework on bootup will automatically disable all unused clocks on bootup unless the clk_ignore_unused kernel parameter is present. Let's add a basic debugging log statement here that shows which clocks are disabled. There is already tracepoint present here as well, but there's nothing like a simple, good ol' fashioned printk for simplicity. Signed-off-by: Brian Masney <bmasney@redhat.com> --- drivers/clk/clk.c | 1 + 1 file changed, 1 insertion(+)