[Precise][Patch 0/1] Revert "samsung-laptop: make the dmi check less strict"

Herton Ronaldo Krzesinski herton.krzesinski at canonical.com
Tue Aug 28 20:06:03 UTC 2012

On Tue, Aug 28, 2012 at 03:34:50PM -0400, joseph.salisbury at canonical.com wrote:
> From: Joseph Salisbury <joseph.salisbury at canonical.com>
> BugLink: http://bugs.launchpad.net/bugs/1028151
> == Precise SRU Justification ==
> Reverting this patch means that samsung specific functionality(ie. rfkill, leds and so on) will not work on any systems not specifically white-listed in the samung-laptop module.  There has been only two people affected by the original bug, lp1012284.
> Not reverting this patch would would mean an 'unknown' number of systems may run into issues when loading the samsung-laptop module.  According to bug lp1028151, there are at least 27 "Affects me too".  There is a work-around in this case, which is to blacklist the module. 

Ack on the revert. BTW, a request to revert on upstream stable (3.2)
should also be made.

The real issue here, is that with commit to fix lp1012284, samsung-laptop
started to load on far more machines, including the ones where brightness
were already being handled by ACPI video module. samsung-laptop and
ACPI video doing the brightness handling don't goes well.

This conclusion is drawn since commit f34cd9ca ("samsung-laptop: don't
handle backlight if handled by acpi/video") would fix the regression too
instead of doing the revert. One of Joseph's testing kernels in the
bug applied f34cd9ca and was confirmed to also fix the problem.

But to pick commit f34cd9ca, it would need to be manually backported, or
including these two commits before to apply successfuly, which are may
be too many changes for anything stable:

The backport is not hard, but the code changes ends up different. Not a
problem, but then looking at samsung-laptop changes, commit f34cd9ca
seems to not be enough to address the regression, or would introduce
another regression for some users, fixed by these commits:
samsung-laptop: unregister ACPI video module for some well known laptops
samsung-laptop: X360 ACPI backlight device is broken

So it would be a lot of changes for an stable, and the quirk problem
doesn't look to be really solved, perhaps only less quirk entries are
needed now (for machines which advertises acpi/video interface, but it
doesn't work, and samsung-laptop is really needed). It seems reasonable
to just revert the change right now on stables.

> == Fix ==
> Revert the following commit:
> commit 9a2e71ce177a1602a0502fbcbb3f11e4bae584e4
> Author: Corentin Chary <corentincj at iksaif.net>
> Date:   Sat Nov 26 11:00:10 2011 +0100
>     samsung-laptop: make the dmi check less strict
> Joseph Salisbury (1):
>   Revert "samsung-laptop: make the dmi check less strict"
>  drivers/platform/x86/samsung-laptop.c |  235 +++++++++++++++++++++++++++++++--
>  1 file changed, 227 insertions(+), 8 deletions(-)
> -- 
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