[PATCH] docs: clk: add documentation to log which clocks have been disabled

[PATCH] docs: clk: add documentation to log which clocks have been disabled

[Brian Masney]

The existing clk documentation has a section that talks about the
clk_ignore_unused kernel parameter. Add additional documentation that
describes how to log which clocks the kernel disables on bootup. This
will log messages like the following to the console on bootup:

    [    1.268115] clk: Disabling unused clocks
    [    1.272167] clk_disable: gcc_usb_clkref_en
    [    1.276389] clk_disable: gcc_usb30_sec_sleep_clk
    [    1.281131] clk_disable: gcc_usb30_prim_sleep_clk
    ...

Signed-off-by: Brian Masney <bmasney@redhat.com>
---
 Documentation/driver-api/clk.rst | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/driver-api/clk.rst b/Documentation/driver-api/clk.rst
index 3cad45d14187..2199c0042e75 100644
--- a/Documentation/driver-api/clk.rst
+++ b/Documentation/driver-api/clk.rst
@@ -258,6 +258,11 @@ 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.
 
+You can see which clocks have been disabled by booting your kernel with these
+parameters:
+
+ tp_printk trace_event=clk:clk_disable
+
 To bypass this disabling, include "clk_ignore_unused" in the bootargs to the
 kernel.
 
-- 
2.39.2

Re: [PATCH] docs: clk: add documentation to log which clocks have been disabled

[Jonathan Corbet]

Brian Masney <bmasney@redhat.com> writes:

> The existing clk documentation has a section that talks about the
> clk_ignore_unused kernel parameter. Add additional documentation that
> describes how to log which clocks the kernel disables on bootup. This
> will log messages like the following to the console on bootup:
>
>     [    1.268115] clk: Disabling unused clocks
>     [    1.272167] clk_disable: gcc_usb_clkref_en
>     [    1.276389] clk_disable: gcc_usb30_sec_sleep_clk
>     [    1.281131] clk_disable: gcc_usb30_prim_sleep_clk
>     ...
>
> Signed-off-by: Brian Masney <bmasney@redhat.com>
> ---
>  Documentation/driver-api/clk.rst | 5 +++++
>  1 file changed, 5 insertions(+)

I've applied this, but...

> diff --git a/Documentation/driver-api/clk.rst b/Documentation/driver-api/clk.rst
> index 3cad45d14187..2199c0042e75 100644
> --- a/Documentation/driver-api/clk.rst
> +++ b/Documentation/driver-api/clk.rst
> @@ -258,6 +258,11 @@ 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.
>  
> +You can see which clocks have been disabled by booting your kernel with these
> +parameters:

...I took the liberty of making that "parameters::" so that the options
would be formatted as a literal block.

> + tp_printk trace_event=clk:clk_disable
> +
>  To bypass this disabling, include "clk_ignore_unused" in the bootargs to the
>  kernel.

Thanks,

jon