linux-kernel - [PATCH] spi: spi-sun6i: enable autosuspend feature

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Message-Id: <20201016083826.31427-1-al.kochet@gmail.com>
Date:   Fri, 16 Oct 2020 11:38:26 +0300
From:   Alexander Kochetkov <al.kochet@...il.com>
To:     Mark Brown <broonie@...nel.org>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>
Cc:     linux-spi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org,
        Alexander Kochetkov <al.kochet@...il.com>
Subject: [PATCH] spi: spi-sun6i: enable autosuspend feature

If SPI is used for periodic polling any sensor, significant delays
sometimes appear. Switching on module clocks during resume lead to delays.
Enabling autosuspend mode causes the controller to not suspend between
SPI transfers and the delays disappear.

Signed-off-by: Alexander Kochetkov <al.kochet@...il.com>
---
 drivers/spi/spi-sun6i.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-sun6i.c b/drivers/spi/spi-sun6i.c
index 38e5b8af7da6..4cc0280e934c 100644
--- a/drivers/spi/spi-sun6i.c
+++ b/drivers/spi/spi-sun6i.c
@@ -22,6 +22,8 @@
 
 #include <linux/spi/spi.h>
 
+#define SUN6I_AUTOSUSPEND_TIMEOUT	2000
+
 #define SUN6I_FIFO_DEPTH		128
 #define SUN8I_FIFO_DEPTH		64
 
@@ -639,9 +641,10 @@ static int sun6i_spi_probe(struct platform_device *pdev)
 		goto err_free_dma_rx;
 	}
 
+	pm_runtime_set_autosuspend_delay(&pdev->dev, SUN6I_AUTOSUSPEND_TIMEOUT);
+	pm_runtime_use_autosuspend(&pdev->dev);
 	pm_runtime_set_active(&pdev->dev);
 	pm_runtime_enable(&pdev->dev);
-	pm_runtime_idle(&pdev->dev);
 
 	ret = devm_spi_register_master(&pdev->dev, master);
 	if (ret) {
-- 
2.17.1