Re: [PATCH] spi: spi-geni-qcom: Don't wait to start 1st transfer if transmitting

From: Akash Asthana
Date: Mon Sep 14 2020 - 09:20:25 EST



On 9/12/2020 11:47 PM, Douglas Anderson wrote:
If we're sending bytes over SPI, we know the FIFO is empty at the
start of the transfer. There's no reason to wait for the interrupt
telling us to start--we can just start right away. Then if we
transmit everything in one swell foop we don't even need to bother
listening for TX interrupts.

In a test of "flashrom -p ec -r /tmp/foo.bin" interrupts were reduced
from ~30560 to ~29730, about a 3% savings.

This patch looks bigger than it is because I moved a few functions
rather than adding a forward declaration. The only actual change to
geni_spi_handle_tx() was to make it return a bool indicating if there
is more to tx.
Reviewed-by: Akash Asthana <akashast@xxxxxxxxxxxxxx>
Signed-off-by: Douglas Anderson<dianders@xxxxxxxxxxxx>

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