Thread (30 messages) 30 messages, 5 authors, 2016-02-22
STALE3751d REVIEWED: 1 (0M)

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

From: Ulf Hansson <hidden>
Date: 2016-02-12 12:53:34
Also in: linux-i2c, linux-mmc, linux-omap, linux-serial, linux-spi

On 11 February 2016 at 00:02, Tony Lindgren [off-list ref] wrote:
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 <redacted>
Cc: Tero Kristo <redacted>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Acked-by: Ulf Hansson <redacted>

Kind regards
Uffe

quoted hunk ↗ jump to hunk
---
 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
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