linux-kernel - [PATCH review for 4.4 19/26] i2c: at91: ensure state is restored after suspending

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Message-ID: <20170925011322.10133-19-alexander.levin@verizon.com>
Date:   Mon, 25 Sep 2017 01:13:43 +0000
From:   "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
Subject: [PATCH review for 4.4 19/26] i2c: at91: ensure state is restored
 after suspending

From: Alexandre Belloni <alexandre.belloni@...e-electrons.com>

[ Upstream commit e3ccc921b7d8fd1fcd10a00720e09823d8078666 ]

When going to suspend, the I2C registers may be lost because the power to
VDDcore is cut. Restore them when resuming.

Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Acked-by: Ludovic Desroches <ludovic.desroches@...rochip.com>
Signed-off-by: Wolfram Sang <wsa@...-dreams.de>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 drivers/i2c/busses/i2c-at91.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index 10835d1f559b..dee0fc421054 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -1131,6 +1131,7 @@ static int at91_twi_suspend_noirq(struct device *dev)
 
 static int at91_twi_resume_noirq(struct device *dev)
 {
+	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
 	int ret;
 
 	if (!pm_runtime_status_suspended(dev)) {
@@ -1142,6 +1143,8 @@ static int at91_twi_resume_noirq(struct device *dev)
 	pm_runtime_mark_last_busy(dev);
 	pm_request_autosuspend(dev);
 
+	at91_init_twi_bus(twi_dev);
+
 	return 0;
 }
 
-- 
2.11.0