[PATCH] ARM: OMAP2+: hwmod: fix _idle() hwmod state sanity check sequence

[Suman Anna]

The omap_hwmod _enable() function can return success without setting
the hwmod state to _HWMOD_STATE_ENABLED for IPs with reset lines when
all of the reset lines are asserted. The omap_hwmod _idle() function
also performs a similar check, but after checking for the hwmod state
first. This triggers the WARN when pm_runtime_get and pm_runtime_put
are invoked on IPs with all reset lines asserted. Reverse the checks
for hwmod state and reset lines status to fix this.

Issue found during a unbind operation on a device with reset lines
still asserted, example backtrace below

 ------------[ cut here ]------------
 WARNING: CPU: 1 PID: 879 at arch/arm/mach-omap2/omap_hwmod.c:2207 _idle+0x1e4/0x240()
 omap_hwmod: mmu_dsp: idle state can only be entered from enabled state
 Modules linked in:
 CPU: 1 PID: 879 Comm: sh Not tainted 4.4.0-00008-ga989d951331a #3
 Hardware name: Generic OMAP5 (Flattened Device Tree)
 [<c0018e60>] (unwind_backtrace) from [<c0014dc4>] (show_stack+0x10/0x14)
 [<c0014dc4>] (show_stack) from [<c037ac28>] (dump_stack+0x90/0xc0)
 [<c037ac28>] (dump_stack) from [<c003f420>] (warn_slowpath_common+0x78/0xb4)
 [<c003f420>] (warn_slowpath_common) from [<c003f48c>] (warn_slowpath_fmt+0x30/0x40)
 [<c003f48c>] (warn_slowpath_fmt) from [<c0028c20>] (_idle+0x1e4/0x240)
 [<c0028c20>] (_idle) from [<c0029080>] (omap_hwmod_idle+0x28/0x48)
 [<c0029080>] (omap_hwmod_idle) from [<c002a5a4>] (omap_device_idle+0x3c/0x90)
 [<c002a5a4>] (omap_device_idle) from [<c0427a90>] (__rpm_callback+0x2c/0x60)
 [<c0427a90>] (__rpm_callback) from [<c0427ae4>] (rpm_callback+0x20/0x80)
 [<c0427ae4>] (rpm_callback) from [<c0427f84>] (rpm_suspend+0x138/0x74c)
 [<c0427f84>] (rpm_suspend) from [<c0428b78>] (__pm_runtime_idle+0x78/0xa8)
 [<c0428b78>] (__pm_runtime_idle) from [<c041f514>] (__device_release_driver+0x64/0x100)
 [<c041f514>] (__device_release_driver) from [<c041f5d0>] (device_release_driver+0x20/0x2c)
 [<c041f5d0>] (device_release_driver) from [<c041d85c>] (unbind_store+0x78/0xf8)
 [<c041d85c>] (unbind_store) from [<c0206df8>] (kernfs_fop_write+0xc0/0x1c4)
 [<c0206df8>] (kernfs_fop_write) from [<c018a120>] (__vfs_write+0x20/0xdc)
 [<c018a120>] (__vfs_write) from [<c018a9cc>] (vfs_write+0x90/0x164)
 [<c018a9cc>] (vfs_write) from [<c018b1f0>] (SyS_write+0x44/0x9c)
 [<c018b1f0>] (SyS_write) from [<c0010420>] (ret_fast_syscall+0x0/0x1c)
 ---[ end trace a4182013c75a9f50 ]---

While at this, fix the sequence in _shutdown() as well, though there
is no easy reproducible scenario.

Fixes: 747834ab8347 ("ARM: OMAP2+: hwmod: revise hardreset behavior")
Signed-off-by: Suman Anna <s-anna at ti.com>
---
Hi Paul,

There are couple of pr_debug statements that only print once the code
flow passes through certain conditions. Not sure if you wanted them
to be printed first thing when entering the functions or only if the
function is really doing something. But it is still not consistent
between _enable(), _idle() and _shutdown().

regards
Suman

 arch/arm/mach-omap2/omap_hwmod.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
index b6d62e4cdfdd..027371c29fb9 100644
--- a/arch/arm/mach-omap2/omap_hwmod.c
+++ b/arch/arm/mach-omap2/omap_hwmod.c
@@ -2207,15 +2207,15 @@ static int _idle(struct omap_hwmod *oh)
 
 	pr_debug("omap_hwmod: %s: idling\n", oh->name);
 
+	if (_are_all_hardreset_lines_asserted(oh))
+		return 0;
+
 	if (oh->_state != _HWMOD_STATE_ENABLED) {
 		WARN(1, "omap_hwmod: %s: idle state can only be entered from enabled state\n",
 			oh->name);
 		return -EINVAL;
 	}
 
-	if (_are_all_hardreset_lines_asserted(oh))
-		return 0;
-
 	if (oh->class->sysc)
 		_idle_sysc(oh);
 	_del_initiator_dep(oh, mpu_oh);
@@ -2262,6 +2262,9 @@ static int _shutdown(struct omap_hwmod *oh)
 	int ret, i;
 	u8 prev_state;
 
+	if (_are_all_hardreset_lines_asserted(oh))
+		return 0;
+
 	if (oh->_state != _HWMOD_STATE_IDLE &&
 	    oh->_state != _HWMOD_STATE_ENABLED) {
 		WARN(1, "omap_hwmod: %s: disabled state can only be entered from idle, or enabled state\n",
@@ -2269,9 +2272,6 @@ static int _shutdown(struct omap_hwmod *oh)
 		return -EINVAL;
 	}
 
-	if (_are_all_hardreset_lines_asserted(oh))
-		return 0;
-
 	pr_debug("omap_hwmod: %s: disabling\n", oh->name);
 
 	if (oh->class->pre_shutdown) {
-- 
2.7.4