Re: [PATCH 2/2] drivers/amba: probe via device tree
From: Grant Likely
Date: Mon May 23 2011 - 11:24:19 EST
On Sat, May 21, 2011 at 5:47 PM, Russell King - ARM Linux
> On Sat, May 21, 2011 at 11:42:34AM -0600, Grant Likely wrote:
>> Russell, it seems to me that the primary behaviour that amba_bus has
>> over platform_bus is the clock management, and secondarily
>> verification of the type of device by the device id. Am I correct, or
>> am I missing something?
> It matches by vendor/device ID just like PCI does, and does the bus
> clock management and power management in a really nice way, which I
> doubt platform devices will ever do.
> The way this discussion is going, I'm going to suggest that we also
> convert PCI stuff to being platform devices too. I don't see the
> point of PCI existing for all the same reasons being given in this
I certainly don't see that as being the direction this discussion is going.
I see a serious question about how best to model AMBA primecell
devices in the device tree, and a similarly serious question about
whether to instantiate them as platform_devices or amba_devices.
Modelled behaviour in this case (clock/power management) is
particularly important, and you're right, platform_devices will never
implement that behaviour in the core code (this issue has already been
pushed back on; see discussions about omap_device).
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