power: gemini-poweroff: Avoid more spurious poweroffs

Even after the previous fix I have experienced more spurious
poweroffs on the gemini SoC. After this fix it finally seems
to go away.

Fixes: f7a388d6cd1c ("power: reset: Add a driver for the Gemini poweroff")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>

drivers/power/reset/gemini-poweroff.c

@@ -130,7 +130,17 @@ static int gemini_poweroff_probe(struct platform_device *pdev)
 	val |= GEMINI_CTRL_ENABLE;
 	writel(val, gpw->base + GEMINI_PWC_CTRLREG);
 
-	/* Now that the state machine is active, clear the IRQ */
+	/* Clear the IRQ */
+	val = readl(gpw->base + GEMINI_PWC_CTRLREG);
+	val |= GEMINI_CTRL_IRQ_CLR;
+	writel(val, gpw->base + GEMINI_PWC_CTRLREG);
+
+	/* Wait for this to clear */
+	val = readl(gpw->base + GEMINI_PWC_STATREG);
+	while (val & 0x70U)
+		val = readl(gpw->base + GEMINI_PWC_STATREG);
+
+	/* Clear the IRQ again */
 	val = readl(gpw->base + GEMINI_PWC_CTRLREG);
 	val |= GEMINI_CTRL_IRQ_CLR;
 	writel(val, gpw->base + GEMINI_PWC_CTRLREG);