[PATCH v1 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
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
 drivers/dma/idma64.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/dma/idma64.c b/drivers/dma/idma64.c
index 78a938969d7d..1b60e73d9322 100644
--- a/drivers/dma/idma64.c
+++ b/drivers/dma/idma64.c
@@ -173,6 +173,10 @@ static irqreturn_t idma64_irq(int irq, void *dev)
 
 	dev_vdbg(idma64->dma.dev, "%s: status=%#x\n", __func__, status);
 
+	/* Since IRQ may be shared, check if DMA controller is powered on */
+	if (status == GENMASK(31, 0))
+		return IRQ_NONE;
+
 	/* Check if we have any interrupt from the DMA controller */
 	if (!status)
 		return IRQ_NONE;
-- 
2.43.0.rc1.1.gbec44491f096