Question: staging: comedi: printk to dev_* version changes

[H Hartley Sweeten]

Greg,

There were a number of patches to the comedi drivers back in
Nov/Dec 2011 similar to this one:

commit 3dbeb83c245bbdc906eb54821d1cd77a25f56741
    Staging: comedi: fix printk issue in serial2002.c

These patches converted the printk's to dev_* versions similar
to this:

-       printk("comedi%d: serial2002: ", dev->minor);
+       dev_dbg(dev->hw_dev, "comedi%d: attached\n", dev->minor);

I don't think these will work like the author intended.

In comedidev.h the hw_dev variable in struct comedi_device is
defined as:

	/* hw_dev is passed to dma_alloc_coherent when allocating async buffers
	 * for subdevices that have async_dma_dir set to something other than
	 * DMA_NONE */
	struct device *hw_dev;

This pointer is only setup by a couple comedi pci drivers. For
most comedi drivers it's going to be NULL.

It appears the "correct" struct device * to use would be the
class_dev pointer in struct comedi_device. As a bonus, this
pointer is created in comedi_fops.c:comedi_alloc_board_minor()
like this:

	info->device->minor = i;
	csdev = device_create(comedi_class, hardware_device,
			      MKDEV(COMEDI_MAJOR, i), NULL, "comedi%i", i);
	if (!IS_ERR(csdev))
		info->device->class_dev = csdev;

So, if I get this right, most of the printk's and current
dev_* variants of this form:

	printk(KERN_INFO "comedi%d: 8255:", dev->minor);

could be changed to simply:

	dev_info(dev->class_dev, "8255:");

And the "comedi" prefix is automatically added. Do I have this right?
I would like to verify this before submitting any patches.

Regards,
Hartley