From 5145351047b216cca13aaca99f939a9a594c6c4d Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Thu, 21 Mar 2013 11:35:49 +0100 Subject: [PATCH 2/3] i2c/omap: drop the lock hard irq context Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/3.12/patches-3.12.0-rt2.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 --- 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 @@ -879,15 +879,12 @@ omap_i2c_isr(int irq, void *dev_id) u16 mask; u16 stat; - spin_lock(&dev->lock); - mask = omap_i2c_read_reg(dev, OMAP_I2C_IE_REG); stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG); + mask = omap_i2c_read_reg(dev, OMAP_I2C_IE_REG); if (stat & mask) ret = IRQ_WAKE_THREAD; - spin_unlock(&dev->lock); - return ret; }