linux-kernel - [PATCH v2 2/2] spi: spi-qcom-qspi: Set an autosuspend delay of 250 ms

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Message-Id: <20200709075113.v2.2.I3c56d655737c89bd9b766567a04b0854db1a4152@changeid>
Date:   Thu,  9 Jul 2020 07:51:45 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     Mark Brown <broonie@...nel.org>, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     swboyd@...omium.org, linux-arm-msm@...r.kernel.org,
        ctheegal@...eaurora.org, mkshah@...eaurora.org, mka@...omium.org,
        Rajendra Nayak <rnayak@...eaurora.org>,
        akashast@...eaurora.org, georgi.djakov@...aro.org,
        Douglas Anderson <dianders@...omium.org>,
        Mukesh Kumar Savaliya <msavaliy@...eaurora.org>,
        linux-kernel@...r.kernel.org, linux-spi@...r.kernel.org
Subject: [PATCH v2 2/2] spi: spi-qcom-qspi: Set an autosuspend delay of 250 ms

In commit cff80645d6d3 ("spi: spi-qcom-qspi: Add interconnect support")
the spi_geni_runtime_suspend() and spi_geni_runtime_resume()
became a bit slower.  Measuring on my hardware I see numbers in the
hundreds of microseconds now.

Let's use autosuspend to help avoid some of the overhead.  Now if
we're doing a bunch of transfers we won't need to be constantly
chruning.

The number 250 ms for the autosuspend delay was picked a bit
arbitrarily, so if someone has measurements showing a better value we
could easily change this.

Fixes: cff80645d6d3 ("spi: spi-qcom-qspi: Add interconnect support")
Signed-off-by: Douglas Anderson <dianders@...omium.org>
Acked-by: Mark Brown <broonie@...nel.org>
Reviewed-by: Rajendra Nayak <rnayak@...eaurora.org>
Tested-by: Rajendra Nayak <rnayak@...eaurora.org>
Reviewed-by: Mukesh Kumar Savaliya <msavaliy@...eaurora.org>
---
This patch could go through the SPI tree or land in the Qualcomm tree.
The patch it Fixes is currently in the Qualcomm tree so if it lands in
the main SPI tree there'd be a bit of a perf regression in the
Qualcomm tree until things merge together in mainline.

Changes in v2: None

 drivers/spi/spi-qcom-qspi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/spi/spi-qcom-qspi.c b/drivers/spi/spi-qcom-qspi.c
index 8fedc605ab7f..b8857a97f40a 100644
--- a/drivers/spi/spi-qcom-qspi.c
+++ b/drivers/spi/spi-qcom-qspi.c
@@ -553,6 +553,8 @@ static int qcom_qspi_probe(struct platform_device *pdev)
 		goto exit_probe_master_put;
 	}
 
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_set_autosuspend_delay(dev, 250);
 	pm_runtime_enable(dev);
 
 	ret = spi_register_master(master);
-- 
2.27.0.383.g050319c2ae-goog