linux-kernel - [PATCH 4.4 19/40] mfd: ab8500-sysctrl: Handle probe deferral

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Message-Id: <20171106094502.118594883@linuxfoundation.org>
Date:   Mon,  6 Nov 2017 10:44:54 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Linus Walleij <linus.walleij@...aro.org>,
        Lee Jones <lee.jones@...aro.org>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.4 19/40] mfd: ab8500-sysctrl: Handle probe deferral

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Linus Walleij <linus.walleij@...aro.org>


[ Upstream commit 7e9c40c63933a643908d686bd89dfc2315e8c70a ]

In the current boot, clients making use of the AB8500 sysctrl
may be probed before the ab8500-sysctrl driver. This gives them
-EINVAL, but should rather give -EPROBE_DEFER.

Before this, the abx500 clock driver didn't probe properly,
and as a result the codec driver in turn using the clocks did
not probe properly. After this patch, everything probes
properly.

Also add OF compatible-string probing. This driver is all
device tree, so let's just make a drive-by-fix of that as
well.

Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Lee Jones <lee.jones@...aro.org>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/mfd/ab8500-sysctrl.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

--- a/drivers/mfd/ab8500-sysctrl.c
+++ b/drivers/mfd/ab8500-sysctrl.c
@@ -99,7 +99,7 @@ int ab8500_sysctrl_read(u16 reg, u8 *val
 	u8 bank;
 
 	if (sysctrl_dev == NULL)
-		return -EINVAL;
+		return -EPROBE_DEFER;
 
 	bank = (reg >> 8);
 	if (!valid_bank(bank))
@@ -115,11 +115,13 @@ int ab8500_sysctrl_write(u16 reg, u8 mas
 	u8 bank;
 
 	if (sysctrl_dev == NULL)
-		return -EINVAL;
+		return -EPROBE_DEFER;
 
 	bank = (reg >> 8);
-	if (!valid_bank(bank))
+	if (!valid_bank(bank)) {
+		pr_err("invalid bank\n");
 		return -EINVAL;
+	}
 
 	return abx500_mask_and_set_register_interruptible(sysctrl_dev, bank,
 		(u8)(reg & 0xFF), mask, value);
@@ -180,9 +182,15 @@ static int ab8500_sysctrl_remove(struct
 	return 0;
 }
 
+static const struct of_device_id ab8500_sysctrl_match[] = {
+	{ .compatible = "stericsson,ab8500-sysctrl", },
+	{}
+};
+
 static struct platform_driver ab8500_sysctrl_driver = {
 	.driver = {
 		.name = "ab8500-sysctrl",
+		.of_match_table = ab8500_sysctrl_match,
 	},
 	.probe = ab8500_sysctrl_probe,
 	.remove = ab8500_sysctrl_remove,