Re: [STLinux Kernel] [PATCH v11 17/19] serial: asc: Adopt readl_/writel_relaxed()

[Peter Griffin]

On Tue, 02 Sep 2014, Daniel Thompson wrote:

> The architectures where this peripheral exists (ARM and SH) have expensive
> implementations of writel(), reliant on spin locks and explicit L2 cache
> management. These architectures provide a cheaper writel_relaxed() which
> is much better suited to peripherals that do not perform DMA. The
> situation with readl()/readl_relaxed()is similar although less acute.
> 
> This driver does not use DMA and will be more power efficient and more
> robust (due to absense of spin locks during console I/O) if it uses the
> relaxed variants.
> 
> This change means the driver is no longer portable and therefore no
> longer suitable for compile testing.
> 
> Signed-off-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
> Cc: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxx>
> Cc: Maxime Coquelin <maxime.coquelin@xxxxxx>
> Cc: Patrice Chotard <patrice.chotard@xxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Jiri Slaby <jslaby@xxxxxxx>
> Cc: kernel@xxxxxxxxxxx
> Cc: linux-serial@xxxxxxxxxxxxxxx

Acked-by: Peter Griffin <peter.griffin@xxxxxxxxxx>

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