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| author |   Aswath Govindraju <a-govindraju@ti.com> | 2020-09-10 17:56:24 +0530 |
|---|---|---|
| committer |   Mark Brown <broonie@kernel.org> | 2020-09-22 01:04:20 +0100 |
| commit | 7b1d96813317358312440d0d07abbfbeb0ef8d22 (patch) | |
| tree | 2a539c1e9bda656c43231becb255a1aab9c03358 /tools/perf/scripts/python/export-to-postgresql.py | |
| parent | spi: npcm-fiu: simplify the return expression of npcm_fiu_probe() (diff) | |
| download | wireguard-linux-7b1d96813317358312440d0d07abbfbeb0ef8d22.tar.xz wireguard-linux-7b1d96813317358312440d0d07abbfbeb0ef8d22.zip | |
spi: omap2-mcspi: Improve performance waiting for CHSTAT
This reverts commit 13d515c796 (spi: omap2-mcspi: Switch to
readl_poll_timeout()).
The amount of time spent polling for the MCSPI_CHSTAT bits to be set on
AM335x-icev2 platform is less than 1us (about 0.6us) in most cases, with
or without using DMA. So, in most cases the function need not sleep.
Also, setting the sleep_usecs to zero would not be optimal here because
ktime_add_us() used in readl_poll_timeout() is slower compared to the
direct addition used after the revert. So, it is sub-optimal to use
readl_poll_timeout in this case.
When DMA is not enabled, this revert results in an increase of about 27%
in throughput and decrease of about 20% in CPU usage. However, the CPU
usage and throughput are almost the same when used with DMA.
Therefore, fix this by reverting the commit which switched to using
readl_poll_timeout().
Fixes: 13d515c796ad ("spi: omap2-mcspi: Switch to readl_poll_timeout()")
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Link: https://lore.kernel.org/r/20200910122624.8769-1-a-govindraju@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'tools/perf/scripts/python/export-to-postgresql.py')
0 files changed, 0 insertions, 0 deletions