drm/imagination: Fix deadlock in soft reset sequence

The soft reset sequence is currently executed from the threaded IRQ
handler, hence it cannot call disable_irq() which internally waits
for IRQ handlers, i.e. itself, to complete.

Use disable_irq_nosync() during a soft reset instead.

Fixes: cc1aeed ("drm/imagination: Implement firmware infrastructure and META FW support")
Cc: [email protected]
Signed-off-by: Alessio Belle <[email protected]>
Reviewed-by: Matt Coster <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Matt Coster <[email protected]>

Author: alessiob-img

drivers/gpu/drm/imagination/pvr_power.c

@@ -510,7 +510,16 @@ pvr_power_reset(struct pvr_device *pvr_dev, bool hard_reset)
 	}
 
 	/* Disable IRQs for the duration of the reset. */
-	disable_irq(pvr_dev->irq);
+	if (hard_reset) {
+		disable_irq(pvr_dev->irq);
+	} else {
+		/*
+		 * Soft reset is triggered as a response to a FW command to the Host and is
+		 * processed from the threaded IRQ handler. This code cannot (nor needs to)
+		 * wait for any IRQ processing to complete.
+		 */
+		disable_irq_nosync(pvr_dev->irq);
+	}
 
 	do {
 		if (hard_reset) {