linux-kernel - [PATCHv3 5/6] spi: omap2-mcspi: add support for pm

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Date:	Fri, 30 Mar 2012 15:50:21 +0530
From:	Shubhrajyoti D <shubhrajyoti@...com>
To:	<spi-devel-general@...ts.sourceforge.net>
CC:	<linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Shubhrajyoti D <shubhrajyoti@...com>
Subject: [PATCHv3 5/6] spi: omap2-mcspi: add support for pm_runtime autosuspend

Adds support for configuring the omap2-mcspi driver use autosuspend for
runtime power management. This can reduce the latency in starting an
spi transfer by not suspending the device immediately following
completion of a transfer. If another transfer then takes place before
the autosuspend timeout (2 secs), the call to resume the device can
return immediately saving some save/ restore cycles.

Acked-by: Govindraj.R <govindraj.raja@...com>
Signed-off-by: Shubhrajyoti D <shubhrajyoti@...com>
---
 drivers/spi/spi-omap2-mcspi.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index 1907ed2..0b0da2f 100644
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -44,6 +44,7 @@
 #include <plat/mcspi.h>
 
 #define OMAP2_MCSPI_MAX_FREQ		48000000
+#define SPI_AUTOSUSPEND_TIMEOUT		2000
 
 #define OMAP2_MCSPI_REVISION		0x00
 #define OMAP2_MCSPI_SYSSTATUS		0x14
@@ -265,7 +266,8 @@ static void omap2_mcspi_restore_ctx(struct omap2_mcspi *mcspi)
 }
 static void omap2_mcspi_disable_clocks(struct omap2_mcspi *mcspi)
 {
-	pm_runtime_put_sync(mcspi->dev);
+	pm_runtime_mark_last_busy(mcspi->dev);
+	pm_runtime_put_autosuspend(mcspi->dev);
 }
 
 static int omap2_mcspi_enable_clocks(struct omap2_mcspi *mcspi)
@@ -1212,6 +1214,8 @@ static int __devinit omap2_mcspi_probe(struct platform_device *pdev)
 	if (status < 0)
 		goto dma_chnl_free;
 
+	pm_runtime_use_autosuspend(&pdev->dev);
+	pm_runtime_set_autosuspend_delay(&pdev->dev, SPI_AUTOSUSPEND_TIMEOUT);
 	pm_runtime_enable(&pdev->dev);
 
 	if (status || omap2_mcspi_master_setup(mcspi) < 0)
-- 
1.7.1

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