linux-kernel - Re: [PATCH v4 05/11] Documentation: PM: amd-pstate: add debugging section for driver loading failure

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Date: Tue, 18 Jun 2024 14:24:58 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: Perry Yuan <perry.yuan@....com>, rafael.j.wysocki@...el.com,
 viresh.kumar@...aro.org, Ray.Huang@....com, gautham.shenoy@....com,
 Borislav.Petkov@....com
Cc: Alexander.Deucher@....com, Xinmei.Huang@....com, Xiaojian.Du@....com,
 Li.Meng@....com, linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 05/11] Documentation: PM: amd-pstate: add debugging
 section for driver loading failure

On 6/17/2024 01:59, Perry Yuan wrote:
> To address issues with the loading of the amd-pstate driver on certain platforms,
> It needs to enable dynamic debugging to capture debug messages during the driver
> loading process. By adding "amd_pstate.dyndbg=+p cppc_acpi.dyndbg=+p  debug
> amd_pstate=active" and loglevel to the kernel command line, then driver debug
> logging is enabled.
> 
> Signed-off-by: Perry Yuan <perry.yuan@....com>
> ---
>   Documentation/admin-guide/pm/amd-pstate.rst | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
> 
> diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
> index 1e0d101b020a..ceeb073c9ada 100644
> --- a/Documentation/admin-guide/pm/amd-pstate.rst
> +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> @@ -472,6 +472,20 @@ operations for the new ``amd-pstate`` module with this tool. ::
>   Diagnostics and Tuning
>   =======================
>   
> +Debugging AMD P-State Driver Loading Issues
> +------------------------------------------
> +
> +If the amd-pstate driver fails to load, additional debug information
> +may be necessary.
> +To capture debug messages for issue analysis, users can add below parameter,
> +"amd_pstate.dyndbg=+p cppc_acpi.dyndbg=+p debug"

What keys off "debug"?  I would expect that dynamic debugging for the 
first two is sufficient.

That being said; isn't everything important shown as a warning now with 
this series?

Is this patch still needed?

> +to the kernel command line. This will enable dynamic debugging and allow better
> +analysis and troubleshooting of the driver loading process.
> +
> +Please note that adding this parameter will only enable debug logging during the
> +driver loading phase and may affect system behavior. Use this option with caution
> +and only for debugging purposes.
> +
>   Trace Events
>   --------------
>