[PATCHv2] wlcore: fix race for WL1271_FLAG_IRQ_RUNNING

[Tony Lindgren]

We set WL1271_FLAG_IRQ_RUNNING in the beginning of wlcore_irq(), and test
for it in wlcore_runtime_resume(). But WL1271_FLAG_IRQ_RUNNING currently
gets cleared too early by wlcore_irq_locked() before wlcore_irq() is done
calling it. And this will race against wlcore_runtime_resume() testing it.

Let's set and clear IRQ_RUNNING in wlcore_irq() so wlcore_runtime_resume()
can rely on it. And let's remove old comments about hardirq, that's no
longer the case as we're using request_threaded_irq().

This fixes occasional annoying wlcore firmware reboots stat start with
"wlcore: WARNING ELP wakeup timeout!" followed by a multisecond latency
when the wlcore firmware gets wrongly rebooted waiting for an ELP wake
interrupt that won't be coming.

Note that I also suspect some form of this issue was the root cause why
the wlcore GPIO interrupt has been often configured as a level interrupt
instead of edge as an attempt to work around the ELP wake timeout errors.

Fixes: fa2648a34e73 ("wlcore: Add support for runtime PM")
Cc: Anders Roxell <anders.rox...@linaro.org>
Cc: Eyal Reizer <ey...@ti.com>
Cc: Guy Mishol <g...@ti.com>
Cc: John Stultz <john.stu...@linaro.org>
Cc: Ulf Hansson <ulf.hans...@linaro.org>
Signed-off-by: Tony Lindgren <t...@atomide.com>
---

Changes since v1:

- Add locking around clear_bit like we do elsewhere in the driver

 drivers/net/wireless/ti/wlcore/main.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/ti/wlcore/main.c 
b/drivers/net/wireless/ti/wlcore/main.c
--- a/drivers/net/wireless/ti/wlcore/main.c
+++ b/drivers/net/wireless/ti/wlcore/main.c
@@ -544,11 +544,6 @@ static int wlcore_irq_locked(struct wl1271 *wl)
        }
 
        while (!done && loopcount--) {
-               /*
-                * In order to avoid a race with the hardirq, clear the flag
-                * before acknowledging the chip.
-                */
-               clear_bit(WL1271_FLAG_IRQ_RUNNING, &wl->flags);
                smp_mb__after_atomic();
 
                ret = wlcore_fw_status(wl, wl->fw_status);
@@ -668,7 +663,7 @@ static irqreturn_t wlcore_irq(int irq, void *cookie)
                disable_irq_nosync(wl->irq);
                pm_wakeup_event(wl->dev, 0);
                spin_unlock_irqrestore(&wl->wl_lock, flags);
-               return IRQ_HANDLED;
+               goto out_handled;
        }
        spin_unlock_irqrestore(&wl->wl_lock, flags);
 
@@ -692,6 +687,11 @@ static irqreturn_t wlcore_irq(int irq, void *cookie)
 
        mutex_unlock(&wl->mutex);
 
+out_handled:
+       spin_lock_irqsave(&wl->wl_lock, flags);
+       clear_bit(WL1271_FLAG_IRQ_RUNNING, &wl->flags);
+       spin_unlock_irqrestore(&wl->wl_lock, flags);
+
        return IRQ_HANDLED;
 }
 
-- 
2.23.0