linux-kernel - Re: [PATCH 4/4] platform/x86: pmc_atom: improve critclk

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Date:   Thu, 4 Mar 2021 11:50:52 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Henning Schild <henning.schild@...mens.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux LED Subsystem <linux-leds@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        linux-watchdog@...r.kernel.org,
        Srikanth Krishnakar <skrishnakar@...il.com>,
        Jan Kiszka <jan.kiszka@...mens.com>,
        Gerd Haeussler <gerd.haeussler.ext@...mens.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Mark Gross <mgross@...ux.intel.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Pavel Machek <pavel@....cz>,
        Michael Haener <michael.haener@...mens.com>
Subject: Re: [PATCH 4/4] platform/x86: pmc_atom: improve critclk_systems
 matching for Siemens PCs

On Thu, Mar 4, 2021 at 9:27 AM Henning Schild
<henning.schild@...mens.com> wrote:

> Siemens industrial PCs unfortunately can not always be properly
> identified the way we used to. An earlier commit introduced code that
> allows proper identification without looking at DMI strings that could
> differ based on product branding.
> Switch over to that proper way and revert commits that used to collect
> the machines based on unstable strings.

> +#include <linux/platform_data/x86/simatic-ipc.h>

> +static int pmc_clk_is_critical(const struct dmi_system_id *d)
> +{
> +       int ret = true;
> +       u32 station_id;
> +
> +       if (!strcmp(d->ident, "SIEMENS AG")) {
> +               if (dmi_walk(simatic_ipc_find_dmi_entry_helper, &station_id))
> +                       ret = false;
> +               else
> +                       ret = (station_id == SIMATIC_IPC_IPC227E ||
> +                              station_id == SIMATIC_IPC_IPC277E);
> +       }
> +
> +       return ret;

Much easier to rewrite it as

if (strcmp(...)) // BTW, do we have a dmi_* helper for that?
  return true;

if (dmi_walk)
  return false;

return station_id == || ...;

> +}

Maybe instead you can rewrite it as a callback in DMI table which
changes a (global, yeah) variable that you simply reassign...



>         if (d) {
> -               clk_data->critical = true;
> -               pr_info("%s critclks quirk enabled\n", d->ident);
> +               clk_data->critical = pmc_clk_is_critical(d);
> +               if (clk_data->critical)
> +                       pr_info("%s critclks quirk enabled\n", d->ident);
>         }

...somewhere here?

Like
  clk_data->critical = global_var;
  if (...)
    pr_info();

It seems it will reduce burden on a callback by dropping strcmp() call.

-- 
With Best Regards,
Andy Shevchenko