[PATCH 6/7] ARM: OMAP2+: Improve omap_device error for driver writers

[tony@atomide.com (Tony Lindgren)]

Drivers using pm_runtime_use_autosuspend() may not get disabled after
-EPROBE_DEFER. On the following device driver probe, hardware state
is different from the PM runtime state causing omap_device to produce
the following error:

omap_device_enable() called from invalid state 1

And with omap_device and omap hardware being picky for PM, this will
block any deeper idle states in hardware.

Let's add a proper error message so driver writers can easily fix
their drivers for PM.

In general, the solution is to fix the drivers to follow the PM
runtime documentation:

1. For sections of code that needs the device disabled, use
   pm_runtime_put_sync_suspend() if pm_runtime_set_autosuspend() has
   been set.

2. For driver exit code, use pm_runtime_dont_use_autosuspend() before
   pm_runtime_put_sync() if pm_runtime_use_autosuspend() has been
   set.

Let's not return with 0 from _od_runtime_resume() as that will
eventually lead into new drivers with broken PM runtime that will
block deeper idle states on omaps.

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Nishanth Menon <nm@ti.com>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
---
 arch/arm/mach-omap2/omap_device.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-omap2/omap_device.c b/arch/arm/mach-omap2/omap_device.c
index 0437537..ebd8369 100644
--- a/arch/arm/mach-omap2/omap_device.c
+++ b/arch/arm/mach-omap2/omap_device.c
@@ -602,8 +602,10 @@ static int _od_runtime_resume(struct device *dev)
 	int ret;
 
 	ret = omap_device_enable(pdev);
-	if (ret)
+	if (ret) {
+		dev_err(dev, "use pm_runtime_put_sync_suspend() in driver?\n");
 		return ret;
+	}
 
 	return pm_generic_runtime_resume(dev);
 }
-- 
2.7.0