Re: [PATCH v2] coresight-stm: adding driver for CoreSight STM component

From: Russell King - ARM Linux
Date: Thu Feb 26 2015 - 17:59:11 EST


On Thu, Feb 26, 2015 at 04:24:53PM -0600, Rob Herring wrote:
> We really shouldn't do private implementation here. It there really
> any reason not to allow readq/writeq generically for 32-bit or just
> for arm32?

My argument has always been that drivers should do the emulation of
64-bit accesses when there is no native support.

IO registers tend to have side effects when read/written. How do we
know whether the low-half or the high-half should be written first?
This isn't something that an architecture can really dictate. What
may be right for one hardware device may not be correct for another.

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