linux-kernel - Re: [PATCH v3 0/9] hwmon: (dell-smm) Add support for WMI SMM interface

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Message-ID: <bee1f739-b41c-4842-bdbd-80315be2d412@redhat.com>
Date:   Mon, 20 Nov 2023 14:03:36 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Armin Wolf <W_Armin@....de>, pali@...nel.org
Cc:     markgross@...nel.org, ilpo.jarvinen@...ux.intel.com,
        jdelvare@...e.com, linux@...ck-us.net,
        platform-driver-x86@...r.kernel.org, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 0/9] hwmon: (dell-smm) Add support for WMI SMM
 interface

Hi,

On 11/6/23 07:43, Armin Wolf wrote:
> This patch series adds support for an alternative SMM calling
> backend to the dell-smm-hwmon driver. The reason for this is
> that on some modern machines, the legacy SMM calling interface
> does not work anymore and the SMM handler can be called over
> ACPI WMI instead.
> 
> The first four patches prepare the driver by allowing to
> specify different SMM calling backends, and by moving most of
> the DMI handling into i8k_init() so that the DMI tables can
> keep their __initconst attributes (the WMI SMM backend driver
> does not probe at module init time). The fifth patch does some
> minor cleanup, while the next three patches implement the new
> WMI SMM calling backend. The last patch adds the machine of
> the user who requested and tested the changes to the fan control
> whitelist.
> 
> If the driver does not detect the legacy SMM interface, either
> because the machine is not whitelisted or because the SMM handler
> does not react, it registers an WMI driver which will then bound
> to the WMI SMM interface and do the remaining initialization.
> 
> The deprecated procfs interface is not supported when using the
> WMI SMM calling backend for the following reason: the WMI driver
> can potentially be instantiated multiple times while the deprectated
> procfs interface cannot. This should not cause any regressions
> because on machines supporting only the WMI SMM interface, the
> driver would, until now, not load anyway.
> 
> All patches where tested on a Dell Inspiron 3505 and a Dell
> OptiPlex 7000.

Thank you for the patches.

Other then the signed int vs unsigned issue which Pali pointed
out this looks good to me, so with that fixed:

Reviewed-by: Hans de Goede <hdegoede@...hat.com>

for the series.

Note that the signed vs unsigned int issue needs to
be fixed in at least both struct smm_regs as well
as in the register parsing, specifically in these lines:

static int wmi_parse_register(u8 *buffer, u32 length, int *reg)

	int *registers[] = {

Also I think it might be better to use u32 instead of
"unsigned int" here. But I'll leave that choice up to you.

Regards,

Hans







> Changes since v2:
> - Rework WMI response parsing
> - Use #define for method number
> 
> Changes since v1:
> - Cc platform driver maintainers
> - Fix formating inside documentation
> 
> Armin Wolf (9):
>   hwmon: (dell-smm) Prepare for multiple SMM calling backends
>   hwmon: (dell-smm) Move blacklist handling to module init
>   hwmon: (dell-smm) Move whitelist handling to module init
>   hwmon: (dell-smm) Move DMI config handling to module init
>   hwmon: (dell-smm) Move config entries out of i8k_dmi_table
>   hwmon: (dell-smm) Introduce helper function for data init
>   hwmon: (dell-smm) Add support for WMI SMM interface
>   hwmon: (dell-smm) Document the WMI SMM interface
>   hwmon: (dell-smm) Add Optiplex 7000 to fan control whitelist
> 
>  Documentation/hwmon/dell-smm-hwmon.rst |  38 +-
>  drivers/hwmon/Kconfig                  |   1 +
>  drivers/hwmon/dell-smm-hwmon.c         | 603 +++++++++++++++++--------
>  drivers/platform/x86/wmi.c             |   1 +
>  4 files changed, 453 insertions(+), 190 deletions(-)
> 
> --
> 2.39.2
>