On Wednesday 15 July 2015 11:00:59 Linus Walleij wrote:
On Wed, Jul 8, 2015 at 4:53 AM, Simon Glass sjg@chromium.org wrote:
This binding differs from that of Linux. Update it and change existing users.
Signed-off-by: Simon Glass sjg@chromium.org
I'm confused by this. Isn't devicetree@vger.kernel.org the place to discuss device tree bindings? This is sent only to the U-Boot list, does this mean that there will now be *two* ontologies for DT bindings? That sounds like a recepie for ... something not good.
+- clock-frequency:
Input clock frequency for UART.This is the real trick is it not?
Is the real commit blurb for this patch something like:
"we want a simple way to look up the clock frequency for our serial ports during early boot, and following clocks = <&...> phandles is too much trouble and might imply having to implement a whole clock framework in U-Boot so we just see a lot of trouble, instead provide a default frequency here"
I suggest in that case, instead do this:
- boot-frequency: input clock frequency at boot time, to be used by boot loaders and other early access.
This would be good for early Linux stuff as well I believe and I do not think it's very controversial.
The CHRP ISA binding defines that a 8250 compatible UART must have this property:
"clock-frequency" S
Standard property, encoded as with encode-int, that shall be the baud-rate generator's clock input frequency (in hertz). Typically, the clock frequency is nominally 1,843,200 Hz. Some devices generate the baud rate input clock by dividing a higher-frequency clock source that is not an exact multiple of 1,843,200 Hz, resulting in a small but acceptable error in the nominal clock frequency. In such cases, the "clock-frequency" shall report the actual nominal frequency. For example, if the baud rate input clock is generated by dividing a 24 MHz clock by 13, the value of the "clock-frequency" property shall be 1846153. Arnd