linux-kernel - Re: [PATCH v3 2/6] platform/x86: huawei-wmi: Add quirks and module parameters

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Date:   Fri, 20 Sep 2019 09:24:08 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ayman Bagabas <ayman.bagabas@...il.com>
Cc:     Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Sinan Kaya <okaya@...nel.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Takashi Iwai <tiwai@...e.de>,
        Stuart Hayes <stuart.w.hayes@...il.com>,
        Matan Ziv-Av <matan@...alib.org>,
        "Enrico Weigelt, metux IT consult" <info@...ux.net>,
        Peng Hao <peng.hao2@....com.cn>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Mattias Jacobsson <2pi@....nu>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/6] platform/x86: huawei-wmi: Add quirks and module
 parameters

Hi,

On 20-09-2019 08:08, Greg Kroah-Hartman wrote:
> On Thu, Sep 19, 2019 at 08:39:07PM -0400, Ayman Bagabas wrote:
>> Introduce quirks and module parameters. 3 quirks are added:
>> 1. Fixes reporting brightness keys twice since it's already handled by
>>     acpi-video.
>> 2. Some models need a short delay when setting battery thresholds to
>>     prevent a race condition when two processes read/write. (will be used later)
>> 3. Matebook X (2017) handles micmute led through the "legacy" interface
>>     which is not currently implemented. Use ACPI EC method to control
>>     this led. (will be used later)
>>
>> 2 module parameters are added to enable this short delay and/or report
>>    brightness keys through this driver.
> 
> module parameters are a pain to manage and handle over time.  Is there
> any way you can "automatically" figure this out, or use a sysfs file
> instead?

The patch also adds dmi matches to set the quirks, so the module params
are there to override those and/or to easily test which are the right options
with new modules. The normal / expected use-case for everything to be set
automatically based on the DMI table.

With that said, the module-params should really always override the dmi values,
so I would like to suggest to make the module-params int-s instead of bool-s
and to do something like this:

static int battery_reset = -1;
static int report_brightness = -1;

	quirks = &quirk_unknown;
	dmi_check_system(huawei_quirks);
	/* If set the module options override the vale from the DMI table */
	if (battery_reset != -1)
		quirks->battery_reset = battery_reset;
	if (report_brightness != -1)
		quirks->report_brightness = report_brightness;

Regards,

Hans