Re: [PATCH V2 2/2] mtd/maps/mtd-ram: add an of-platform driver

[Wolfram Sang <w.sang@pengutronix.de>]

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On Sat, Jun 06, 2009 at 09:14:08AM +0100, David Woodhouse wrote:

> On Fri, 2009-06-05 at 14:05 +0200, Wolfram Sang wrote:
> > Create an of-aware driver using the now exported generic functions from
> > plat-ram.c. Also add the documentation for the binding. Partitions are
> > not yet supported. Tested on a phyCORE-MPC5200B-IO.
> 
> Do we have an ack for the device-tree bindings? 
> 
> It _would_ be possible to hook up RAM through the existing of_physmap
> driver, I think -- although it would be slightly less efficient that
> way.
> 
> Maybe cleaner from the device-tree POV though. And if we want to put a
> special case in the _code_ to make it more efficient, we can do that.

During development, I also checked physmap_of.c and found this binding:

        {
                .type           = "rom",
                .compatible     = "direct-mapped"
        },

which made some sense to me and I thought about .type = "ram". However, I then
found this in the code:

/* Helper function to handle probing of the obsolete "direct-mapped"
 * compatible binding, which has an extra "probe-type" property
 * describing the type of flash probe necessary. */
static struct mtd_info * __devinit obsolete_probe(struct of_device *dev,
                                                  struct map_info *map)
{
[...]

        dev_warn(&dev->dev, "Device tree uses obsolete \"direct-mapped\" "
                 "flash binding\n");

My conclusion was then that a mtd-ram binding wouldn't belong here, but I have
maybe misinterpreted things...

Regards,

   Wolfram

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