On Tue, Sep 06, 2016 at 11:04:38AM +0800, Chen-Yu Tsai wrote:

On Tue, Sep 6, 2016 at 3:31 AM, Maxime Ripard
[off-list ref] wrote:

quoted

Hi Jorik,

On Sat, Sep 03, 2016 at 02:09:32PM +0200, Jorik Jonker wrote:

quoted

On Fri, Sep 02, 2016 at 09:04:25AM +0200, Maxime Ripard wrote:

quoted

Unfortunately, these pins can be used for other purposes as well, so
we cannot make force that decision down to our users.

Yes, but since the associated peripheral is disabled, the users are free to
configure other functions/peripherals, right? I mean something like this in
pseudo-DT:

/soc/pio: pinctrl at 01c20800/uart1_pins:
  allwinner,pins = "PG6, PG7";
/soc/pio: pinctrl at 01c20800/foo0_pins:
  allwinner,pins = "PG6, PG7";
  ..
/soc/uart1: serial at serial@01c28400:
  pinctrl-0 = <&uart1_pins>;
  status = "disabled";
/soc/bar:
  pinctrl-0 = <&uart1_pins>;
  status = "disabled";

Assuming Linux/DT allows this, this would force nothing, only offer choice
and ease of use.

Hmm, sorry, I went over your patches too quickly...

That's a great compromise I think. Chen-Yu, any opinion on this?

In short, I'm ok with it. But please put an explicit

    status = "disabled";

and probably a comment about how/where the peripheral can be
used in the board dts.

I intended to do this for the Banana Pis. Though my original plan
was to enable Raspberry Pi compatible peripherals by default, and
list the other peripherals that are defined by the vendor as
"disabled".

"Defined by the vendor" means that the vendor has some sort of
document associating the gpio header pins with the peripherals,
as shown in:

    http://www.orangepi.org/Docs/Pindefinition.html#CON3_Definition

This should make it easier for the average user to enable the
peripherals. I'm not sure we should list _all_ possible ones
though. That would make the list very large, and some might
end up never being used.

Having a clear limit on what we can put and what we can't isn't very
easy to do though. Any suggestion on how we can solve that?

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: not available
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20160906/ad000d69/attachment-0001.sig>