[PATCH v6 14/16] OMAP2+: UART: Take console_lock in suspend path if not taken

[Govindraj]

On Wed, Oct 12, 2011 at 12:31 AM, Kevin Hilman <khilman at ti.com> wrote:
> "Govindraj.R" <govindraj.raja at ti.com> writes:
>
>> 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