Probably a CMS thing. printk is probably also discouraged, these days. pr_warn/info/..() or dev_warn/info/err...() should be used.
Also for anyone writing kernel code, this is indispensable: http://elixir.free-electrons.com/linux/latest/source
Also for anyone writing kernel code, this is indispensable: http://elixir.free-electrons.com/linux/latest/source
Nowadays, lots of code could be using devm_kmalloc, devm_ioremap, etc which will release the resources automatically when the driver detaches from the device.