OMAP2+: PM: fix watchdog boot when runtime PM is disabled

Fix boot crash in watchdog driver when runtime PM is disabled.

When runtime PM is disabled, devices should be left enabled so that all device accesses in drivers will succeed even though the runtime PM get/put calls are noops.

This is already the case for all devices, but the WDT init has its own hwmod postsetup which was not taking this into account.

This fixes a boot crash where the first device access in the WDT probe function would crash a booting kernel.

Cc Paul Walmsley <[email protected]>

Signed-off-by Kevin Hilman <[email protected]>

---
Tony, as this is a boot crash, it should probably be queued for v3.0. However, since OMAP2PLUS_TYPICAL always enables runtime PM, this is unlikely to be seen unless specifically testing with runtime PM disabled.

Fix boot crash in watchdog driver when runtime PM is disabled.

When runtime PM is disabled, devices should be left enabled so that all device accesses in drivers will succeed even though the runtime PM get/put calls are noops.

This is already the case for all devices, but the WDT init has its own hwmod postsetup which was not taking this into account.

This fixes a boot crash where the first device access in the WDT probe function would crash a booting kernel.

Cc Paul Walmsley<[email protected]>

Signed-off-by Kevin Hilman<[email protected]>

---
Tony, as this is a boot crash, it should probably be queued for v3.0. However, since OMAP2PLUS_TYPICAL always enables runtime PM, this is unlikely to be seen unless specifically testing with runtime PM disabled.

  arch/arm/mach-omap2/io.c |    4 ++++
  1 files changed, 4 insertions(+), 0 deletions(-)

arch/arm/mach-omap2/io.c +4 -0

index 441e79d..95c08aa 100644
@@ -395,7 +395,11 @@ void __init omap2_init_common_infrastructure(void)
  	 * XXX ideally we could detect whether the MPU WDT was currently
  	 * enabled here and make this conditional
  	 */
+#ifdef CONFIG_PM_RUNTIME
  	postsetup_state = _HWMOD_STATE_DISABLED;
+#else
+	postsetup_state = _HWMOD_STATE_ENABLED;
+#endif
  	omap_hwmod_for_each_by_class("wd_timer",
  				     _set_hwmod_postsetup_state,
  				&postsetup_state);

Quoted 12 lines · Kevin Hilman

Fix boot crash in watchdog driver when runtime PM is disabled.

When runtime PM is disabled, devices should be left enabled so that all device accesses in drivers will succeed even though the runtime PM get/put calls are noops.

This is already the case for all devices, but the WDT init has its own hwmod postsetup which was not taking this into account.

This fixes a boot crash where the first device access in the WDT probe function would crash a booting kernel.

Quoted 7 lines

Cc Paul Walmsley<[email protected]>

Signed-off-by Kevin Hilman<[email protected]>

---
Tony, as this is a boot crash, it should probably be queued for v3.0. However, since OMAP2PLUS_TYPICAL always enables runtime PM, this is unlikely to be seen unless specifically testing with runtime PM disabled.

This patch is exactly same as the one I submitted on Jan 5, 2011 for the same issue. Here is the patchwork link for the same.

https://patchwork.kernel.org/patch/453481/

Paul had a valid concern about the boot-loader leaving the watchdog enabled. More on this in below thread.

http://www.spinics.net/lists/arm-kernel/msg110937.html

Paul's concern is valid, and could be addressed by making that init code actually check if the WDT is currently active (as suggested by the comment there.)

In the mean time, this simple fix should be applied to prevent a boot crash, IMO.