is_err checking

[Julia Lawall]

Code like the following looks a bit clunky to me:

if (IS_ERR(data->clk) && PTR_ERR(data->clk) != -EPROBE_DEFER)

Is there any reason not to always use eg

data->clk == ERR_PTR(-EPROBE_DEFER)

Code of the latter form is a bit more popular.  Perhaps one could want
something like:

IS_ERR_VALUE(data->clk, -EPROBE_DEFER)

but IS_ERR_VALUE is laready used for something else.

julia