linux-kernel - [PATCH v2] i2c: at91: ensure state is restored after suspending

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Message-Id: <20170216172759.27837-1-alexandre.belloni@free-electrons.com>
Date:   Thu, 16 Feb 2017 18:27:59 +0100
From:   Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:     Wolfram Sang <wsa@...-dreams.de>
Cc:     Ludovic Desroches <ludovic.desroches@...el.com>,
        linux-i2c@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org,
        Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Subject: [PATCH v2] i2c: at91: ensure state is restored after suspending

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>
---
Changes in v2:
 - don't cache unecessary registers and simply call at91_init_twi_bus()


 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 0b86c6173e07..c925a690cb32 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -1180,6 +1180,7 @@ 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)) {
@@ -1191,6 +1192,8 @@ 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