[PATCH v3 04/22] dmaengine: ste_dma40: Fix probe runtime PM disable

[Linus Walleij <linusw@kernel.org>]

Some d40_probe() error paths jump to destroy_cache before runtime PM has
been enabled for the DMA controller device. The label unconditionally
calls pm_runtime_disable(), which increments disable_depth even though
this probe attempt never enabled runtime PM.

Track whether this probe attempt enabled runtime PM before disabling it on
the error path. This is not about a later deferred-probe retry, since the
driver is registered with platform_driver_probe(); it keeps the probe
unwind balanced.

The interrupt handler uses pm_runtime_get_if_active() and cannot
acknowledge a pending interrupt while runtime PM is disabled. Request the
IRQ only after enabling runtime PM so the handler cannot enter an
unacknowledged interrupt loop during probe.

Fixes: 0618c077a8c2 ("dmaengine: ste_dma40: Fix PM disable depth imbalance in d40_probe")
Reported-by: sashiko-bot@kernel.org
Closes: https://lore.kernel.org/dmaengine/20260618051539.15E201F000E9@smtp.kernel.org/
Assisted-by: LLM
Signed-off-by: Linus Walleij <linusw@kernel.org>
---
 drivers/dma/ste_dma40.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
index 451a87992058..28fcd196d95b 100644
--- a/drivers/dma/ste_dma40.c
+++ b/drivers/dma/ste_dma40.c
@@ -3543,6 +3543,7 @@ static int __init d40_probe(struct platform_device *pdev)
 	struct resource *res;
 	struct resource res_lcpa;
 	int num_reserved_chans;
+	bool runtime_pm_enabled = false;
 	u32 val;
 	int ret;
 
@@ -3630,12 +3631,6 @@ static int __init d40_probe(struct platform_device *pdev)
 		goto destroy_cache;
 	}
 
-	ret = request_irq(base->irq, d40_handle_interrupt, 0, D40_NAME, base);
-	if (ret) {
-		d40_err(dev, "No IRQ defined\n");
-		goto destroy_cache;
-	}
-
 	if (base->plat_data->use_esram_lcla) {
 
 		base->lcpa_regulator = regulator_get(base->dev, "lcla_esram");
@@ -3664,6 +3659,13 @@ static int __init d40_probe(struct platform_device *pdev)
 	pm_runtime_mark_last_busy(base->dev);
 	pm_runtime_set_active(base->dev);
 	pm_runtime_enable(base->dev);
+	runtime_pm_enabled = true;
+
+	ret = request_irq(base->irq, d40_handle_interrupt, 0, D40_NAME, base);
+	if (ret) {
+		d40_err(dev, "No IRQ defined\n");
+		goto destroy_cache;
+	}
 
 	ret = d40_dmaengine_init(base, num_reserved_chans);
 	if (ret)
@@ -3699,7 +3701,8 @@ static int __init d40_probe(struct platform_device *pdev)
 		regulator_disable(base->lcpa_regulator);
 		regulator_put(base->lcpa_regulator);
 	}
-	pm_runtime_disable(base->dev);
+	if (runtime_pm_enabled)
+		pm_runtime_disable(base->dev);
 
  report_failure:
 	d40_err(dev, "probe failed\n");

-- 
2.55.0