[PATCH 1/2] mfd: twl6030: fix lockdep recursion warning on setting wake IRQs

Todd Poynor
2011-09-26T23:44:44Z

LOCKDEP explicitly sets all irq_desc locks as a single lock-class,
causing "possible recursive locking detected" when the TWL RTC
driver calls through enable_irq_wake to twl6030_irq_set_wake,
which recursively calls irq_set_irq_wake. Although the
irq_desc and lock are different, LOCKDEP treats these as
equivalent, presumably due to problems that can be incurred
when locking more than one irq_desc, so best to avoid this.

Suspend/resume actions implemented as PM notifiers to avoid
touch the TWL core for this.

Signed-off-by: Todd Poynor <toddpoynor@google.com>
---

This patch applies on top of the patch from Santosh:
[PATCH] mfd: twl6030: Setup irq_wake infrastructure.

If PM notifiers aren't preferred then could change
twl-core to add suspend/resume callbacks, was trying to
make a lower-impact change.

This complexity assumes there are systems that include twl6030
and don't want its IRQs to act as wakeup. Alternatively,
could just always enable wake for twl6030's IRQ.

drivers/mfd/twl6030-irq.c | 46 +++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/twl6030-irq.c b/drivers/mfd/twl6030-irq.c
index 4477134..7d6553c 100644
--- a/drivers/mfd/twl6030-irq.c
+++ b/drivers/mfd/twl6030-irq.c
@@ -37,6 +37,7 @@
#include <linux/kthread.h>
#include <linux/i2c/twl.h>
#include <linux/platform_device.h>
+#include <linux/suspend.h>

#include "twl-core.h"

@@ -83,8 +84,42 @@ static int twl6030_interrupt_mapping[24] = {
/*----------------------------------------------------------------------*/

static unsigned twl6030_irq_base;
+static int twl_irq;
+static bool twl_irq_wake_enabled;

static struct completion irq_event;
+static atomic_t twl6030_wakeirqs = ATOMIC_INIT(0);
+
+static int twl6030_irq_pm_notifier(struct notifier_block *notifier,
+ unsigned long pm_event, void *unused)
+{
+ int chained_wakeups;
+
+ switch (pm_event) {
+ case PM_SUSPEND_PREPARE:
+ chained_wakeups = atomic_read(&twl6030_wakeirqs);
+
+ if (chained_wakeups && !twl_irq_wake_enabled) {
+ if (enable_irq_wake(twl_irq))
+ pr_err("twl6030 IRQ wake enable failed\n");
+ else
+ twl_irq_wake_enabled = true;
+ } else if (!chained_wakeups && twl_irq_wake_enabled) {
+ disable_irq_wake(twl_irq);
+ twl_irq_wake_enabled = false;
+ }
+
+ break;
+ default:
+ break;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block twl6030_irq_pm_notifier_block = {
+ .notifier_call = twl6030_irq_pm_notifier,
+};

/*
* This thread processes interrupts reported by the Primary Interrupt Handler.
@@ -189,9 +224,12 @@ static inline void activate_irq(int irq)

int twl6030_irq_set_wake(struct irq_data *d, unsigned int on)
{
- int twl_irq = (int)irq_get_chip_data(d->irq);
+ if (on)
+ atomic_inc(&twl6030_wakeirqs);
+ else
+ atomic_dec(&twl6030_wakeirqs);

- return irq_set_irq_wake(twl_irq, on);
+ return 0;
}

/*----------------------------------------------------------------------*/
@@ -353,6 +391,9 @@ int twl6030_init_irq(int irq_num, unsigned irq_base, unsigned irq_end)
pr_err("twl6030: could not claim irq%d: %d\n", irq_num, status);
goto fail_irq;
}
+
+ twl_irq = irq_num;
+ register_pm_notifier(&twl6030_irq_pm_notifier_block);
return status;
fail_irq:
free_irq(irq_num, &irq_event);
@@ -365,6 +406,7 @@ fail_kthread:

int twl6030_exit_irq(void)
{
+ unregister_pm_notifier(&twl6030_irq_pm_notifier_block);

if (twl6030_irq_base) {
pr_err("twl6030: can't yet clean up IRQs?\n");
--
1.7.3.1