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

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Message-ID: <20200106102834.31301-2-ckeepax@opensource.cirrus.com>
Date:   Mon, 6 Jan 2020 10:28:34 +0000
From:   Charles Keepax <ckeepax@...nsource.cirrus.com>
To:     <lee.jones@...aro.org>
CC:     <linux-kernel@...r.kernel.org>, <patches@...nsource.cirrus.com>
Subject: [PATCH 2/2] mfd: madera: Wait for boot done before accessing any other registers

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@...nsource.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