Re-enable lirc_serial driver

[jbollacke]

The driver lirc_serial has been renamed to ir_serial in linux v4.10. See torvalds/linux@fa5dc29
But this driver is needed for some IR receivers e.g. Atric IR Receiver to work.

First added in af3d9e7.
Removed in 491b701 (due to migration to linux v4.10).

This PR does:

• Enable ir_serial as module
• Add alias named lirc_serial so scripts referencing this module (e.g. autostart.sh) won't break

[HiassofT]

Please add CONFIG_IR_SERIAL_TRANSMITTER=y - LE8 contained CONFIG_LIRC_SERIAL_TRANSMITTER=y as well.

And I'd strongly suggest dropping the modprobe.d file with the alias. People can just change the module name in .config/modules-load.d/*.conf. This is a lot cleaner than adding support for legacy configurations which will then probably linger around forever.

[HiassofT]

Just had a look at the serial IR driver, by default it uses the rc6-mce map. This means MCE remotes will work out of the box and use in-kernel decoding. Running userspace lircd in parallel to that will result in double keypresses.

So people will have to adjust their configs anyway and remove their lircd.conf if they use an MCE remote (or some other remote supported by LE out of the box).

[jbollacke]

As far as I know CONFIG_IR_SERIAL_TRANSMITTER is y by default. See torvalds/linux@fa5dc29#diff-9b924813a0f386da12899ca6acdf420cR404 for reference. So adding it would just make it more verbose.

I agree with dropping the module alias.

[jbollacke]

Will squash later

[lrusak]

Thanks!

[MilhouseVH]

If you run make oldconfig on the Generic kernel now you are prompted to enable CONFIG_IR_SERIAL_TRANSMITTER or not - the default is "yes", but being verbose and specifying a value means there is no confusion or need to prompt. Will add CONFIG_IR_SERIAL_TRANSMITTER=y in the next kernel bump.