[PATCH v2 1/1] idma64: Don't try to serve interrupts when device is powered off

[Andy Shevchenko]

When iDMA 64-bit device is powered off, the IRQ status register
is all 1:s. This is never happen in real case and signalling that
the device is simply powered off. Don't try to serve interrupts
that are not ours.

Fixes: 667dfed98615 ("dmaengine: add a driver for Intel integrated DMA 64-bit")
Reported-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Closes: https://lore.kernel.org/r/700bbb84-90e1-4505-8ff0-3f17ea8bc631@xxxxxxxxx
Tested-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
v2: added tag (Heiner), moved check to be before the debug message
 drivers/dma/idma64.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/dma/idma64.c b/drivers/dma/idma64.c
index 78a938969d7d..1398814d8fbb 100644
--- a/drivers/dma/idma64.c
+++ b/drivers/dma/idma64.c
@@ -171,6 +171,10 @@ static irqreturn_t idma64_irq(int irq, void *dev)
 	u32 status_err;
 	unsigned short i;
 
+	/* Since IRQ may be shared, check if DMA controller is powered on */
+	if (status == GENMASK(31, 0))
+		return IRQ_NONE;
+
 	dev_vdbg(idma64->dma.dev, "%s: status=%#x\n", __func__, status);
 
 	/* Check if we have any interrupt from the DMA controller */
-- 
2.43.0.rc1.1.gbec44491f096