Re: [PATCH v1 02/10] powerpc/mm: rework io-workaround invocation.

[Christoph Hellwig]

On Tue, Aug 13, 2019 at 08:11:34PM +0000, Christophe Leroy wrote:
> ppc_md.ioremap() is only used for I/O workaround on CELL platform,
> so indirect function call can be avoided.
> 
> This patch reworks the io-workaround and ioremap() functions to
> use static keys for the activation of io-workaround.
> 
> When CONFIG_PPC_IO_WORKAROUNDS or CONFIG_PPC_INDIRECT_MMIO are not
> selected, the I/O workaround ioremap() voids and the static key is
> not used at all.

Why bother with the complex static key?  ioremap isn't exactly a fast
path.  Just make it a normal branch if enabled, with the option to
compile it out entirely as in your patch.