Re: [PATCH 1/2] ARM: Tegra: dt: Split out separate Tegra SoC DT

On Mon, May 2, 2011 at 12:00 PM, Stephen Warren [off-list ref] wrote:

Olof Johansson wrote at Sunday, May 01, 2011 8:56 AM:

quoted

On Fri, Apr 29, 2011 at 10:12:30PM -0600, Stephen Warren wrote:

quoted

tegra250.dts describes everything within the Tegra SoC, but leaves all
optional devices disabled.

tegra-harmony.dts is now the configuration of the SoC for the board,
i.e. it enables the optional devices that are required for the board,
and provides any required platform data for those devics.

The prevents every Tegra board having to repeat all the basic internal
SoC wiring.

Signed-off-by: Stephen Warren <redacted>

Acked-by: Olof Johansson <redacted>

A mostly unrelated question below.

[...]

quoted

+   serial@70006000 {
+           compatible = "nvidia,tegra250-uart";

I know this is how Grant specified it, but shouldn't these also have
a compat for ns16550?

At present, I'm not sure it is technically compatible. If you look at
drivers/tty/serial/of_serial.c, you'll see:

static struct of_device_id __devinitdata of_platform_serial_table[] = {
...
       { .compatible = "ns16550",  .data = (void *)PORT_16550, },
...
       { .compatible = "nvidia,tegra250-uart",  .data = (void *)PORT_XSCALE, },

That PORT_XSCALE is different to the ns16550 entry. Arguably, that
field should be something that comes from the device tree, just
like e.g. reg-shift, but it certainly doesn't right now.

Grant, what are your thoughts on this?

Heh, when I added that line I just mirrored the 'type' of 16550 as
detected by the 8250.c driver when it probes and made a mental note
that it should be revisited.  I don't know the hardware very well, so
I cannot easily say what the right thing to do is, but making it
ns16550 compatible does seem to make sense.

g.