On Wed, Oct 12, 2011 at 12:31 AM, Kevin Hilman [off-list ref] wrote:

"Govindraj.R" [off-list ref] writes:

quoted

In suspend path the console_lock is taken by uart_port_suspend
however when no_console_suspend is used console_lock is not taken.

During system wide suspend omap_pwr_domain hooks cut all
clocks that are left enabled. So its unsafe to proceed printing after
clocks are cut by pwr_domain hooks.

As I've mentioned in previous reviews, when no_console_suspend is
enabled, the user has explicitly requested console output during
suspend. ?In order to support that, we should not be cutting clocks at
all in that mode.

One way to address this would be to just disable runtime PM in the
->prepare method of the driver if no_console_suspend is enabled.

Okay fine exploring this option, right API's would be to use
pm_runtime_forbid/allow.

<<SNIP>>

+static int serial_omap_runtime_prepare(struct device *dev)
+{
+       if (!console_suspend_enabled)
+               pm_runtime_forbid(dev);
+
+       return 0;
+}
+
+static void serial_omap_runtime_complete(struct device *dev)
+{
+       if (!console_suspend_enabled)
+               pm_runtime_allow(dev);
+}
+
 static const struct dev_pm_ops serial_omap_dev_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(serial_omap_suspend, serial_omap_resume)
        SET_RUNTIME_PM_OPS(serial_omap_runtime_suspend,
                                serial_omap_runtime_resume, NULL)
+       .prepare = serial_omap_runtime_prepare,
+       .complete =  serial_omap_runtime_complete,
 };

<<SNIP>>

But to either use runtime forbid or disable we have ensure that
power_domain hooks don't go ahead and disable
the clocks with omap_device_idle as *runtime forbid or disable will
not set runtime_status to RPM_SUSPENDED*
and will stay in RPM_ACTIVE if we call runtime disable or forbid from
active state.

in power_domain hooks we just check the pm_runtime_status_suspended
this will be false even if
we do runtime disable/forbid and it will cut uart clocks always.

So we may need below check also:

diff --git a/arch/arm/plat-omap/omap_device.c b/arch/arm/plat-omap/omap_device.c
index 26aee5c..286a534 100644
--- a/arch/arm/plat-omap/omap_device.c
+++ b/arch/arm/plat-omap/omap_device.c

@@ -592,7 +592,8 @@ static int _od_suspend_noirq(struct device *dev)

        ret = pm_generic_suspend_noirq(dev);

-       if (!ret && !pm_runtime_status_suspended(dev)) {
+       if (!ret && pm_runtime_enabled(dev) &&
+                       !pm_runtime_status_suspended(dev)) {
                if (pm_generic_runtime_suspend(dev) == 0) {
                        omap_device_idle(pdev);
                        od->flags |= OMAP_DEVICE_SUSPENDED;


--

Thanks,
Govindraj.R