| Date | Tue, 2 Sep 2014 14:42:58 +0100 | From | Peter Griffin <> | Subject | Re: [STLinux Kernel] [PATCH v11 17/19] serial: asc: Adopt readl_/writel_relaxed() |
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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@linaro.org> > Cc: Srinivas Kandagatla <srinivas.kandagatla@gmail.com> > Cc: Maxime Coquelin <maxime.coquelin@st.com> > Cc: Patrice Chotard <patrice.chotard@st.com> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Jiri Slaby <jslaby@suse.cz> > Cc: kernel@stlinux.com > Cc: linux-serial@vger.kernel.org
Acked-by: Peter Griffin <peter.griffin@linaro.org>
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