spi: spi-geni-qcom: Don't set the cs if it was already right

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Setting the chip select on the Qualcomm geni SPI controller isn't
exactly cheap.  Let's cache the current setting and avoid setting the
chip select if it's already right.

Using "flashrom" to read or write the EC firmware on a Chromebook
shows roughly a 25% reduction in interrupts and a 15% speedup.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200626151946.1.I06134fd669bf91fd387dc6ecfe21d44c202bd412@changeid
Signed-off-by: Mark Brown <broonie@kernel.org>

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Douglas Anderson 2020-06-26 15:19:50 -07:00 • committed by Mark Brown

parent 1ac6f21a94

commit 638d8488ae

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drivers/spi/spi-geni-qcom.c

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