[PATCHv8 00/23]I2C big cleanup

Felipe Balbi balbi at ti.com
Thu Sep 13 01:33:28 EDT 2012

On Wed, Sep 12, 2012 at 03:27:22PM -0700, Kevin Hilman wrote:
> Shubhrajyoti D <shubhrajyoti at ti.com> writes:
> [...]
> >
> > This is the cleanup only series.
> >   
> > Tested on omap4sdp and 3430sdp.
> It would be extremely helpful if you would describe how this was tested.
> And for me, it would be a source of extreme joy if you described any PM
> testing.
> I gave this some additional PM testing on 3430/n900, 3530/Overo,
> 3730/OveroSTORM, 3730/Beagle-xM and 4430/Panda.
> I tested v3.6-rc5 which passed all PM tests and then added this series
> (by merging the i2c-embedded/i2c-next branch.)  PM tests then fail.
> At least on 3530/Overo and 3730/Overo, CORE no longer hits retenion (or
> off) during idle.  
> The easy way to notice this is to see that even when no i2c transactions
> are happening, the runtime PM status for omap_i2c.1 is remains 'active':
> # cat omap_i2c.*/power/runtime_status 
> active
> suspended
> Of course that means that clocks are never gated during idle, and CORE
> will never hit retention.
> I noticed it because my PM tests detected that the CORE powerdomain was
> not transitioning to retention (or off) during idle.
> To reproduce, simply enable UART timeouts so CORE will hit retention:
> echo 3000 > /sys/devices/platform/omap_uart.0/power/autosuspend_delay_ms
> echo 3000 > /sys/devices/platform/omap_uart.1/power/autosuspend_delay_ms
> echo 3000 > /sys/devices/platform/omap_uart.2/power/autosuspend_delay_ms
> echo 3000 > /sys/devices/platform/omap_uart.3/power/autosuspend_delay_ms
> and check the core_pwrm state counters:
> cat /debug/pm_debug/count
> wait > 3 seconds for the UART autosuspend timers to kick in.  At this
> point, CORE should be transitioning to retenion in idle (determined by
> noticing that the RET counter for core_pwrdm is increasing.)

I just ran same tests on pandaboard and i2c is suspended actually,
though no power domain transitions to RET. Do we not have retention
while idle on pandaboard ?

See below for a few results... First I ran this script to set everything


echo "mounting proc"
mount -t proc none /proc

echo "mounting sysfs"
mount -t sysfs none /sys

echo "mounting debugfs"
mount -t debugfs none /debug

echo "UART autosuspend delay"
echo 3000 > /sys/devices/platform/omap_uart.0/power/autosuspend_delay_ms
echo 3000 > /sys/devices/platform/omap_uart.1/power/autosuspend_delay_ms
echo 3000 > /sys/devices/platform/omap_uart.2/power/autosuspend_delay_ms
echo 3000 > /sys/devices/platform/omap_uart.3/power/autosuspend_delay_ms

echo "check omap_i2c.* status"
cat /sys/devices/platform/omap_i2c.*/power/runtime_status

echo "check CORE pm counters"
grep "^core_pwrdm" /debug/pm_debug/count

Then I triggered a few i2c transfers by reading regulator status through

# cat /sys/class/regulator/regulator.*/status
[  507.469299] omap_i2c omap_i2c.1: omap_i2c_runtime_resume
# [  509.010711] omap_i2c omap_i2c.1: omap_i2c_runtime_suspend
cat /sys/devices/platform/omap_i2c.*/power/runtime_status

notice the prints I've added... I don't know what could go wrong only on
Overo that i2c doesn't suspend. Can you add this debugging patch just
for me to see if, at least, omap_i2c_runtime_suspend is being called ?

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index c78431a..ac61664 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -1238,6 +1238,8 @@ static int omap_i2c_runtime_suspend(struct device *dev)
 	struct omap_i2c_dev *_dev = platform_get_drvdata(pdev);
 	u16 iv;
+	dev_info(dev, "%s\n", __func__);
 	_dev->iestate = omap_i2c_read_reg(_dev, OMAP_I2C_IE_REG);
 	omap_i2c_write_reg(_dev, OMAP_I2C_IE_REG, 0);
@@ -1277,6 +1279,8 @@ static int omap_i2c_runtime_resume(struct device *dev)
 	if (_dev->iestate)
 		omap_i2c_write_reg(_dev, OMAP_I2C_IE_REG, _dev->iestate);
+	dev_info(dev, "%s\n", __func__);
 	return 0;
 #endif /* CONFIG_PM_RUNTIME */

this is on top of Wolfram's for-next branch, btw. Maybe you should also


to your .config just in case.


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