[Lenny400] Slightly later kernel/distro version

H. Nikolaus Schaller hns at goldelico.com
Fri Sep 1 14:07:15 CEST 2017


Hi Paul,

> Am 01.09.2017 um 13:53 schrieb Paul Boddie <paul at boddie.org.uk>:
> 
> On Friday 1. September 2017 12.13.38 H. Nikolaus Schaller wrote:
>> 
> 
> [PWM]
> 
>> Maybe it is possible to simply turn it on by gpio-pinmux...
> 
> I'm not sure where to start with that, but given that there is a generic PWM 
> backlight device, I suppose that a usable driver combined with that device 
> should be enough to start with.

If the jz4730 pad can be pinmuxed to "gpio" it should just be a pinmux
entry and some optional gpio-hog in the board device tree...

This was for a long time the only GTA04 backlight control...

> 
> [Keypad]
> 
>> Yes, the original jzchar driver did a lot of magic which should be done
>> completely different with modern kernels.
> 
> David mentioned some odd "encoded" character driver stuff that I haven't 
> investigated yet.
> 
> [Device tree]
> 
>> If you have a newer version, I can simply add it so that we can show it
>> around...
> 
> I can include that with my patches, sure.

Fine!

> 
> [RTC]
> 
>> IMHO, the RTC is simply an nxp,pcf8563 which has a modern driver:
>> 
>> http://elixir.free-electrons.com/linux/v4.13-rc7/source/drivers/rtc/rtc-pcf
>> 8563.c
>> 
>> So having a SoC I2C master driver is the limitation.
> 
> Right. I'll try and look at what the 2.6 kernel does with the RTC via I2C.

IMHO there is nothing special with RTC and I2C. The RTC driver just looks for
the chip and presents some /dev/rtc0. Everything else is handled by user-space
by the hwclock command and API.

So as soon as you can i2cdump the RTC it should start working (with proper
DT entry of course).

> 
> [...]
> 
>> What I am no longer finding is the nice documentation of the gpios on
>> kwaak... Do you have a link to that? Then I could set up something from
>> documentation (schematics).
> 
> There are archived versions of these documents which I can link to from the 
> projects area.

I have linked some parts but IMHO the gpio documentation is missing:

http://projects.goldelico.com/p/letux400/page/HardwareDocs/

http://download.goldelico.com/letux-400/files/

So updating the links would be good.

> I might create some separate pages or update any that already 
> exist.

> 
> I also noted down some things about clocks and pins which might be useful, if 
> I've understood the existing code correctly.

Fine!

> 
> [...]
> 
>> Fine! Then I can try to integrate them into the Letux kernel tree.
> 
> So, I'll try and tidy up the patches and send them here, then.

BR and thanks,
Nikolaus



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