net: ipa: have ipa_clock_get() return a value

We currently assume no errors occur when enabling or disabling the
IPA core clock and interconnects.  And although this commit exposes
errors that could occur, we generally assume this won't happen in
practice.

This commit changes ipa_clock_get() and ipa_clock_put() so each
returns a value.  The values returned are meant to mimic what the
runtime power management functions return, so we can set up error
handling here before we make the switch.  Have ipa_clock_get()
increment the reference count even if it returns an error, to match
the behavior of pm_runtime_get().

More details follow.

When taking a reference in ipa_clock_get(), return 0 for the first
reference, 1 for subsequent references, or a negative error code if
an error occurs.  Note that if ipa_clock_get() returns an error, we
must not touch hardware; in some cases such errors now cause entire
blocks of code to be skipped.

When dropping a reference in ipa_clock_put(), we return 0 or an
error code.  The error would come from ipa_clock_disable(), which
now returns what ipa_interconnect_disable() returns (either 0 or a
negative error code).  For now, callers ignore the return value;
if an error occurs, a message will have already been logged, and
little more can actually be done to improve the situation.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 13 deletions

diff --git a/drivers/net/ipa/ipa_smp2p.c b/drivers/net/ipa/ipa_smp2p.c
index 0d15438a79e2..f84d6523636e 100644
--- a/drivers/net/ipa/ipa_smp2p.c
+++ b/drivers/net/ipa/ipa_smp2p.c
@@ -150,24 +150,26 @@ static void ipa_smp2p_panic_notifier_unregister(struct ipa_smp2p *smp2p)
 static irqreturn_t ipa_smp2p_modem_setup_ready_isr(int irq, void *dev_id)
 {
 	struct ipa_smp2p *smp2p = dev_id;
+	int ret;
 
 	mutex_lock(&smp2p->mutex);
 
-	if (!smp2p->disabled) {
-		int ret;
-
-		/* The clock needs to be active for setup */
-		ipa_clock_get(smp2p->ipa);
+	if (smp2p->disabled)
+		goto out_mutex_unlock;
+	smp2p->disabled = true;		/* If any others arrive, ignore them */
 
-		ret = ipa_setup(smp2p->ipa);
-		if (ret)
-			dev_err(&smp2p->ipa->pdev->dev,
-				"error %d from ipa_setup()\n", ret);
-		smp2p->disabled = true;
+	/* The clock needs to be active for setup */
+	ret = ipa_clock_get(smp2p->ipa);
+	if (WARN_ON(ret < 0))
+		goto out_clock_put;
 
-		ipa_clock_put(smp2p->ipa);
-	}
+	/* An error here won't cause driver shutdown, so warn if one occurs */
+	ret = ipa_setup(smp2p->ipa);
+	WARN(ret != 0, "error %d from ipa_setup()\n", ret);
 
+out_clock_put:
+	(void)ipa_clock_put(smp2p->ipa);
+out_mutex_unlock:
 	mutex_unlock(&smp2p->mutex);
 
 	return IRQ_HANDLED;
@@ -206,7 +208,7 @@ static void ipa_smp2p_clock_release(struct ipa *ipa)
 	if (!ipa->smp2p->clock_on)
 		return;
 
-	ipa_clock_put(ipa);
+	(void)ipa_clock_put(ipa);
 	ipa->smp2p->clock_on = false;
 }