When SPI wake up from OFF mode, CS is in the wrong state: force it to the inactive state.
During the system life, I monitored the CS behavior using a oscilloscope.
I also activated debug in omap2_mcspi, so I saw when driver disable the clocks and restore context when device is not used.
Each time the CS was in the correct state.
It was only when system was put suspend to ram with off-mode activated that on resume the CS was in wrong state( ie activated).
Changelog:
* Change from v1 to v2:
Rebase on linus/master (after 2.6.37-rc1)
Do some clean-up and fix indentation on both patches
Add more explanations for patch 2
* Change from v2 to v3:
Use directly resume function of spi_master instead of using function
from spi_device as Grant Likely pointed it out.
Force this transition explicitly for each CS used by a device.
* Change from v3 to v4:
Patch clean-up according to Kevin Hilman and checkpatch.
Now force CS to be in inactive state only if it was inactive when it was
suspended.
* Change from v4 to v5:
Rebase on linus/master (after 2.6.37-rc3)
Collapse some lines as pointed by Grant Likely
Fix a spelling
* Change from v5 to v6:
Rebase on linus/master (after 2.6.37-rc7)
Use CONFIG_SUSPEND instead of CONFIG_PM
Didn't use legacy PM methods anymore. Instead, add a struct dev_pm_ops and add the resume method there.
Fix multi-line comment style
Signed-off-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx>
---
drivers/spi/omap2_mcspi.c | 40 ++++++++++++++++++++++++++++++++++++++++
1 files changed, 40 insertions(+), 0 deletions(-)
diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
index 2a651e6..a17ea97 100644
--- a/drivers/spi/omap2_mcspi.c
+++ b/drivers/spi/omap2_mcspi.c
@@ -1305,10 +1305,50 @@ static int __exit omap2_mcspi_remove(struct platform_device *pdev)
/* work with hotplug and coldplug */
MODULE_ALIAS("platform:omap2_mcspi");
+#ifdef CONFIG_SUSPEND
+/*
+ * When SPI wake up from off-mode, CS is in activate state. If it was in
+ * unactive state when driver was suspend, then force it to unactive state at
+ * wake up.
+ */
+static int omap2_mcspi_resume(struct device *dev)
+{
+ struct spi_master *master = dev_get_drvdata(dev);
+ struct omap2_mcspi *mcspi = spi_master_get_devdata(master);
+ struct omap2_mcspi_cs *cs;
+
+ omap2_mcspi_enable_clocks(mcspi);
+ list_for_each_entry(cs, &omap2_mcspi_ctx[master->bus_num - 1].cs,
+ node) {
+ if ((cs->chconf0 & OMAP2_MCSPI_CHCONF_FORCE) == 0) {
+
+ /*
+ * We need to toggle CS state for OMAP take this
+ * change in account.
+ */
+ MOD_REG_BIT(cs->chconf0, OMAP2_MCSPI_CHCONF_FORCE, 1);
+ __raw_writel(cs->chconf0, cs->base + OMAP2_MCSPI_CHCONF0);
+ MOD_REG_BIT(cs->chconf0, OMAP2_MCSPI_CHCONF_FORCE, 0);
+ __raw_writel(cs->chconf0, cs->base + OMAP2_MCSPI_CHCONF0);
+ }
+ }
+ omap2_mcspi_disable_clocks(mcspi);
+ return 0;
+}
+#else
+#define omap2_mcspi_resume NULL
+#endif
+
+static const struct dev_pm_ops omap2_mcspi_pm_ops = {
+ .resume = omap2_mcspi_resume,
+};
+
static struct platform_driver omap2_mcspi_driver = {
.driver = {
.name = "omap2_mcspi",
.owner = THIS_MODULE,
+ .pm = &omap2_mcspi_pm_ops
+
},
.remove = __exit_p(omap2_mcspi_remove),
};
--
1.7.0.4
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