From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 21 Mar 2013 11:35:49 +0100
Subject: i2c/omap: drop the lock hard irq context
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.6/older/patches-4.6.2-rt5.tar.xz

The lock is taken while reading two registers. On RT the first lock is
taken in hard irq where it might sleep and in the threaded irq.
The threaded irq runs in oneshot mode so the hard irq does not run until
the thread the completes so there is no reason to grab the lock.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/i2c/busses/i2c-omap.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -995,15 +995,12 @@ omap_i2c_isr(int irq, void *dev_id)
 	u16 mask;
 	u16 stat;
 
-	spin_lock(&omap->lock);
-	mask = omap_i2c_read_reg(omap, OMAP_I2C_IE_REG);
 	stat = omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG);
+	mask = omap_i2c_read_reg(omap, OMAP_I2C_IE_REG);
 
 	if (stat & mask)
 		ret = IRQ_WAKE_THREAD;
 
-	spin_unlock(&omap->lock);
-
 	return ret;
 }
 
