Hello,

On Thu, Jul 07, 2016 at 10:27:51AM +0200, Arnd Bergmann wrote:

On Thursday, July 7, 2016 8:28:00 AM CEST Uwe Kleine-K?nig wrote:

quoted

On Wed, Jul 06, 2016 at 10:09:39PM +0200, Arnd Bergmann wrote:

quoted

On Wednesday, July 6, 2016 7:30:57 PM CEST Uwe Kleine-K?nig wrote:

quoted

On Wed, Jul 06, 2016 at 05:22:40PM +0200, Arnd Bergmann wrote:

quoted

On Monday, July 4, 2016 5:50:09 PM CEST Uwe Kleine-K?nig wrote:

quoted

On Mon, Jul 04, 2016 at 05:43:03PM +0200, Arnd Bergmann wrote:

quoted

On Monday, July 4, 2016 5:34:12 PM CEST Uwe Kleine-K?nig wrote:

quoted

Add support for two led triggers per UART instance that blink on
transmission and reception of data respectively.

If this is something we may want to do on other platforms as well,
we should perhaps not hardwire the name of the imx tty device in
the led trigger name.

I cannot follow. If we have several serial lines and a trigger for each
of them, they must get different names. Using the device's name to
distinguish them seems like a good and obvious idea.

The main problem I see is if someone puts the name of the trigger into
a dtb file, as this hardcodes the connection between the Linux driver
name and numbering system with the device tree binding, which are normally
separate.

If we could derive the trigger name from the "/aliases/serial%d" property
in DT instead, it would get a little more portable.

Alternatively we could invent a more dtish way as aliases seem to be
frowned upon [1], something like:

	led#0 {
		label = "userled";
		linux,default-trigger = &uart1, "tx";
	};

	uart1: serial at 43f90000 {
		...
		#trigger-cells = <1>;
	};

That looks nice, but I don't see how we could implement this in a
backwards compatible way, as we don't know whether the first cell
of the property is a phandle or a string.

If we agree, that this is OS-agnostic, we could use "default-trigger" as
property name instead of "linux,default-trigger".
 
Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-K?nig            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |