Re: [PATCH] acpi-video: Fix backlight taking 2 steps on a brightness key press

["Bjørn Mork" <bjorn@mork.no>]

Hans de Goede <hdegoede@redhat.com> writes:

> Hi All,
>
> Here is my cleaned-up version of Linus' patch to fix the 2 steps on a
> brightness key press problem.
>
> Changes compared to Linus' version:
> -Move the global variables to inside struct acpi_video_device
> -Rebase on top of Rafael's linux-pm linux-next branch (so on top of the
>  revert of changing the brightness_switch_enabled default)
>
> I've tested this on a laptop affected by the 2 steps problem and I can confirm
> that it fixes the 2 steps issue under normal usage. I managed to trigger the
> race by generating a heavy io-load, as exptected hitting the race has no
> unwanted side-effects other then taking 2 steps instead of one.
>
> Bjørn can you test this patch on your system and confirm that it does not
> break things for you please ? Note that in order to apply it you first need
> to do: "git revert 886129a8eebebec", as the revert has not yet reached
> Linus' tree AFAIK.

Tested and verified that it still works fine for me, so feel free to add

Tested-by: Bjørn Mork <bjorn@mork.no>

if you like.

But as noted earlier, I believe this poses another risk if anyone has a
config using bool input values:

-static bool brightness_switch_enabled = 1;
-module_param(brightness_switch_enabled, bool, 0644);
+static int brightness_switch_enabled = -1;
+module_param(brightness_switch_enabled, int, 0644);


I wonder if it wouldn't be better to just redefine the behaviour of
"brightness_switch_enabled = 1" to the new delayed response scheme and
avoid changing the type of this parameter?



Bjørn
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