On Tuesday 17 November 2015 09:26:49 Guenter Roeck wrote:

quoted

This syntax is confusing, as we normally associate it with an error
condition.  Instead, I'd use:

  if (of_property_read_u32(np, "bus-width", &bus_width) == 0)

Or maybe better

        if (!of_property_read_u32(np, "bus-width", &bus_width))

I would also prefer the latter, but it doesn't matter much either way.

quoted

Or, for more clarity:

  of_property_read_u32(np, "bus-width", &bus_width);
  if (bus_width)

If you choose this version (which I think is my preferred method, don't
forget to initialise 'bus_width' to zero.

Ignoring an error and depending on bus_width==0 to determine if the property
was provided seems odd, especially since it would "hide" if the bus-width
property is set to 0. In the original code, this would be detected as error.

Right.

Another option would be

	ret = of_property_read_u32(np, "bus-width", &bus_width);
	/* no bus width provided, default to 32-bit */
	if (ret)
		bus_width = 32;

	syscon_config.val_bits = bus_width;
	syscon_config.reg_stride = syscon_config.val_bits / 8;

which has the same effect but seems a little clearer to me.

	Arnd