Hi Armin,
Thanks for your input. While looking at new WMI drivers which I could
use as a reference, I stumbled upon
https://patchwork.kernel.org/project/platform-driver-x86/patch/20221004214332.35934-1-soyer@xxxxxx/
which was sent last week and implements a driver for the same WMI
interface. So I guess there is not much left for me to implement here,
I'll just follow that patch.
Regards,
Lorenz
On Sat, Oct 15 2022 at 03:26:50 +02:00:00, Armin Wolf <W_Armin@xxxxxx>
wrote:
Am 15.10.22 um 00:12 schrieb Lorenz Brun:
Hi x86 platform list,
I'm considering contributing support for the usage mode/tablet mode
switch for some Lenovo laptops (including the popular IdeaPad Flex
series).
There is already an out-of-tree driver at
https://github.com/lukas-w/yoga-usage-mode which works well,
but I'd like to get this support upstream.
I have a few questions regarding the best approach:
1. There is the ideapad-laptop module already which deals with a
bunch
of functionality related to these laptops, but not the mode switch.
Do
you prefer a separate driver or should the functionality be added to
ideapad-laptop?
2. The existing out-of-tree driver uses a WMI interface to access
mode
information. Should I work on the WMI layer or should I figure out
which EC registers to use to get the functionality independently? If
yes, how do we want to identify support for this type of mode switch?
Regards,
Lorenz
Hi,
1) In my opinion, the ideapad-laptop driver uses a totally different
interface than the out of tree driver, so it would make sense to
create a separate driver.
2) You should stick to the WMI interface. The vendor could change the
internal EC registers at any time, which would drastically limit the
portability and
reliability of the driver in question. Also, there exists a whole WMI
subsystem inside the linux kernel, which for example supports
automatic discovery of
WMI devices, etc.
Looking at the out-of-tree driver in question, it seems that it does
not fully utilize the WMI subsystem. If you want to upstream it, i
suggest a rewrite
to fix this. Since the driver is quite small, it should be relatively
easy. Optionally, you could also add support for LENOVO_GSENSOR_DATA,
since it also
has some interesting methods. However, the scope of the driver is
completely up to you.
There are already some WMI-based drivers inside the kernel, maybe
they can serve as an inspiration?
Armin Wolf
