We got Backlight Controls! BUT...

[Robert Small]

This is excellent news. Hopefully Boran can weigh in with his
hardware/ACPI/DSDT knowledge.


Thanks,
Robert.

On Fri, 28 Oct 2016, 11:07 a.m. Salvatore Prestipino, <
salv.prestipino at gmail.com> wrote:

> Hi all, I'm the same person that last time have wrote with the name
> Okusho, with this
> https://drive.google.com/drive/folders/0B_uxdqSfzNGwTjF2M2w2VDBzb0k?usp=sharing
> set of patches from Shobhit Kumar, and a fix from Viric, that I have ported
> on kernel 4.8, we can enable pwm-lpss backlight control on our device! (see
> the huge but below). with the backlight control the battery life of our
> device is highly enhanced, I don't see drawbacks on my system.
> BUT for make this set of patches work, I had to modify my DSDT table, to
> enable pwm-lpss probe. In my system the probe is blocked from a DSDT
> variable, OSSL. So since DSDT table edit is not a portable solution we have
> to understand how to initialize correctly the OSSL variable.
> what I know on this variable is that is initialized at boot time, end. I
> know only this, in interent I haven't found any information, there are only
> people that have removed completely the OSSL variable from their DSDT
> table, but this is not a solution for me.
> I have some hypothesis on this variable, in the bios, in the option secure
> boot i've read something like "... in this system openssl is used for
> enable secure boot..." so  i think that OSSL=OpenSSL, and I think that at
> boot time either if the secure boot option is active or not, the system
> checks if in the efi partition is present the secure boot key (I have
> formatted my efi partition, so I don't have the secure boot key) if is
> present, the OSSL variable is initialized. This system is understandable,
> if the system don't have the secure boot key, some hardware components are
> disabled (in fact the OSSL variable don't enable only the pwm-lpss). I
> think that there are two posible condition to enable the OSSL variable:
> 1)in the system there is the original efi partition, not formatated, that
> have the secure boot key
> 2) if you enable the secure boot option in the bios, you are anyway able
> to boot in Ubuntu.
> I think that condition two is the right one, but I don't know if condition
> 2 is equivalent to 1, maybe someone of you can test this patches and see if
> they enable the backlight control, without DSDT modification, and report
> its efi secure boot situation, and if condition 2 is verified.
> to test it, you can use the patchs above, or maybe my kernel at
> https://drive.google.com/drive/folders/0B_uxdqSfzNGwOG1UUEh2ckM4LVU?usp=sharing (this
> kernel contains the sound patches too, i've read that Paul Mansfield have
> lost his speakers (I'm sorry) so BE CAREFUL), let's try to understand how
> OSSL works!
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