On Fri, Jan 17, 2014 at 06:06:41PM +0800, Chen-Yu Tsai wrote :

On Fri, Jan 17, 2014 at 5:39 PM, Alexandre Belloni
[off-list ref] wrote:

quoted

Maybe it is not completely related but I think it needs to be thought
about while you are it:

The TI wilink chips (TiWi, wl12xx, wl18xx) have wifi on SDIO and BT on
UART but they share the same clock. So, the next question would be what
if I just want to enable one or the other (and take that decision at
runtime) ?

Some Broadcom chips (BCM4329/4330) and the AP6210 found on CubieTruck
are like this as well. In our case, the SD/MMC host driver hasn't been
mainlined yet. But BT on UART is independent and usable.

quoted

Where do I put the pinctrl/clocks/regulators in the DT ? I guess it can
become an issue to enable both WiFi and BT at the same time if both SDIO
and UART are trying to handle the same pinctrl and regulators.

Shouldn't the clocks and regulators be registered in the DT _AS_ clocks
and regulators? fixed-regulator already accepts GPIO lines. fixed-rate-clock
mentions GPIOs in DT bindings, but doesn't seem to use them in the code.
We'd still need a device to tie them to, especially in the UART use case.

Yeah, I meant if you tie your clock/pinctrl/reset/regulator to both the
BT and the WiFI nodes because it is shared, you'll at least get a
warning or one of the two won't be working.

Or we could try rfkill devices. Not saying it's the correct way, but it is
a solution.

You'll get the same issue there. Two rfkill devices sharing the same
clock or reset for example.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com