linux-kernel - Re: [PATCH 4/5] platform/x86: dell-ddv: Add "force" module param

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Message-ID: <3a13b29e-e1f1-ef0b-338b-b89797981287@redhat.com>
Date:   Mon, 30 Jan 2023 16:06:31 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Armin Wolf <W_Armin@....de>, markgross@...nel.org
Cc:     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 4/5] platform/x86: dell-ddv: Add "force" module param

Hi,

On 1/26/23 20:40, Armin Wolf wrote:
> Until now, the dell-wmi-ddv driver needs to be manually
> patched and compiled to test compatibility with unknown
> DDV WMI interface versions.
> Add a module param to allow users to force loading even
> when a unknown interface version was detected. Since this
> might cause various unwanted side effects, the module param
> is marked as unsafe.
> Also update kernel-parameters.txt.
> 
> Signed-off-by: Armin Wolf <W_Armin@....de>

Thank you for your patch, I've applied this patch to my review-hans 
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.

Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.

Regards,

Hans


> ---
>  Documentation/admin-guide/kernel-parameters.txt |  3 +++
>  drivers/platform/x86/dell/dell-wmi-ddv.c        | 13 +++++++++++--
>  2 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 6cfa6e3996cf..9bbff5113427 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1024,6 +1024,9 @@
>  	dell_smm_hwmon.fan_max=
>  			[HW] Maximum configurable fan speed.
> 
> +	dell_wmi_ddv.force=
> +			[HW] Do not check for supported WMI interface versions.
> +
>  	dfltcc=		[HW,S390]
>  			Format: { on | off | def_only | inf_only | always }
>  			on:       s390 zlib hardware support for compression on
> diff --git a/drivers/platform/x86/dell/dell-wmi-ddv.c b/drivers/platform/x86/dell/dell-wmi-ddv.c
> index 58fadb74e86a..9695bf493ea6 100644
> --- a/drivers/platform/x86/dell/dell-wmi-ddv.c
> +++ b/drivers/platform/x86/dell/dell-wmi-ddv.c
> @@ -34,6 +34,10 @@
>  #define DELL_EPPID_LENGTH	20
>  #define DELL_EPPID_EXT_LENGTH	23
> 
> +static bool force;
> +module_param_unsafe(force, bool, 0);
> +MODULE_PARM_DESC(force, "Force loading without checking for supported WMI interface versions");
> +
>  enum dell_ddv_method {
>  	DELL_DDV_BATTERY_DESIGN_CAPACITY	= 0x01,
>  	DELL_DDV_BATTERY_FULL_CHARGE_CAPACITY	= 0x02,
> @@ -349,8 +353,13 @@ static int dell_wmi_ddv_probe(struct wmi_device *wdev, const void *context)
>  		return ret;
> 
>  	dev_dbg(&wdev->dev, "WMI interface version: %d\n", version);
> -	if (version < DELL_DDV_SUPPORTED_VERSION_MIN || version > DELL_DDV_SUPPORTED_VERSION_MAX)
> -		return -ENODEV;
> +	if (version < DELL_DDV_SUPPORTED_VERSION_MIN || version > DELL_DDV_SUPPORTED_VERSION_MAX) {
> +		if (!force)
> +			return -ENODEV;
> +
> +		dev_warn(&wdev->dev, "Loading despite unsupported WMI interface version (%u)\n",
> +			 version);
> +	}
> 
>  	data = devm_kzalloc(&wdev->dev, sizeof(*data), GFP_KERNEL);
>  	if (!data)
> --
> 2.30.2
>