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SubjectRe: [PATCH] platform/x86: thinkpad_acpi: add adaptive_kbd_modes parameter
Bjørn Mork <bjorn@mork.no> wrote:
> Eric Wong <e@80x24.org> writes:
> > Eric Wong <e@80x24.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....

Thanks for checking it out.

> 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;
> > +}

Right, 0 is allowed; and it will lock the current mode into
place...

> 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;
> > }

Not a busy loop, since new_mode will reset at HOME_MODE (0)
and then it'll hit "new_mode == mode" and remain locked in
to the current mode.

> Or am I reading this wrong?

It seems that way. My initial iteration of this patch did
have a busy loop, but I fixed it before publishing :)

Thanks again for the review.

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