[PATCH 2/2] mfd: madera: Wait for boot done before accessing any other registers

[Charles Keepax <ckeepax@opensource.cirrus.com>]

It is advised to wait for the boot done bit to be set before reading
any other register, update the driver to respect this.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
---
 drivers/mfd/madera-core.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/madera-core.c b/drivers/mfd/madera-core.c
index f41ce408259fb..edf3d22dd82f9 100644
--- a/drivers/mfd/madera-core.c
+++ b/drivers/mfd/madera-core.c
@@ -199,7 +199,7 @@ EXPORT_SYMBOL_GPL(madera_name_from_type);
 #define MADERA_BOOT_POLL_INTERVAL_USEC		5000
 #define MADERA_BOOT_POLL_TIMEOUT_USEC		25000
 
-static int madera_wait_for_boot(struct madera *madera)
+static int madera_wait_for_boot_noack(struct madera *madera)
 {
 	ktime_t timeout;
 	unsigned int val = 0;
@@ -226,6 +226,13 @@ static int madera_wait_for_boot(struct madera *madera)
 		ret = -ETIMEDOUT;
 	}
 
+	return ret;
+}
+
+static int madera_wait_for_boot(struct madera *madera)
+{
+	int ret = madera_wait_for_boot_noack(madera);
+
 	/*
 	 * BOOT_DONE defaults to unmasked on boot so we must ack it.
 	 * Do this even after a timeout to avoid interrupt storms.
@@ -547,6 +554,12 @@ int madera_dev_init(struct madera *madera)
 	regcache_cache_only(madera->regmap, false);
 	regcache_cache_only(madera->regmap_32bit, false);
 
+	ret = madera_wait_for_boot_noack(madera);
+	if (ret) {
+		dev_err(madera->dev, "Device failed initial boot: %d\n", ret);
+		goto err_reset;
+	}
+
 	/*
 	 * Now we can power up and verify that this is a chip we know about
 	 * before we start doing any writes to its registers.
@@ -652,7 +665,7 @@ int madera_dev_init(struct madera *madera)
 
 	ret = madera_wait_for_boot(madera);
 	if (ret) {
-		dev_err(madera->dev, "Device failed initial boot: %d\n", ret);
+		dev_err(madera->dev, "Failed to clear boot done: %d\n", ret);
 		goto err_reset;
 	}
 
-- 
2.11.0