linux-kernel - Re: [PATCH] platform/x86: thinkpad_acpi: add adaptive_kbd

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Date:   Sun, 25 Nov 2018 11:21:14 +0100
From:   Bjørn Mork <bjorn@...k.no>
To:     Eric Wong <e@...24.org>
Cc:     Henrique de Moraes Holschuh <ibm-acpi@....eng.br>,
        Shuduo Sang <shuduo.sang@...onical.com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        linux-kernel@...r.kernel.org, ibm-acpi-devel@...ts.sourceforge.net,
        platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH] platform/x86: thinkpad_acpi: add adaptive_kbd_modes parameter

Eric Wong <e@...24.org> writes:
> Eric Wong <e@...24.org> wrote:
>> The above setting with this change and the following keymap
>> preserves my sanity on the atrocious adaptive keyboard on
>> the 2nd-gen X1 Carbon:
>
> Any comments on this patch?  The Esc and F-keys on the keyboard
> are still numb and I'll be getting rid of the laptop in a few
> days; but maybe my patch can still be useful to others...

I've read through and I like it, FWIW.  A brilliant idea. I don't have
the hardare to test the patch, though....

But I do wonder if you aren't missing an empty mask protection
somewhere?  If I read this right, then there is nothing preventing you
from writing 0 here:

> +static ssize_t adaptive_kbd_modes_store(struct device *dev,
> +			struct device_attribute *attr,
> +			const char *buf, size_t count)
> +{
> +	unsigned long t;
> +
> +	if (parse_strtoul(buf, (1 << LAYFLAT_MODE) - 1, &t))
> +		return -EINVAL;
> +
> +	adaptive_kbd_modes = (unsigned int)t;
> +	return count;
> +}


And then I believe you have a busy loop here:

> @@ -3815,20 +3838,20 @@ static int adaptive_keyboard_set_mode(int new_mode)
>  
>  static int adaptive_keyboard_get_next_mode(int mode)
>  {
> -	size_t i;
> -	size_t max_mode = ARRAY_SIZE(adaptive_keyboard_modes) - 1;
> -
> -	for (i = 0; i <= max_mode; i++) {
> -		if (adaptive_keyboard_modes[i] == mode)
> -			break;
> -	}
> +	int max_mode = fls(adaptive_kbd_modes);
> +	int new_mode = mode >= max_mode ? HOME_MODE : mode + 1;
>  
> -	if (i >= max_mode)
> -		i = 0;
> -	else
> -		i++;
> +	/* make sure the new mode is allowed by the user */
> +	while (!(adaptive_kbd_modes & (1 << new_mode))) {
> +		new_mode++;
> +		if (new_mode > max_mode)
> +			new_mode = HOME_MODE;
>  
> -	return adaptive_keyboard_modes[i];
> +		/* maybe the user disabled all other modes: */
> +		if (new_mode == mode)
> +			return mode;
> +	}
> +	return new_mode;
>  }


Or am I reading this wrong?



Bjørn