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authorAlexander Kochetkov <al.kochet@gmail.com>2014-11-22 23:47:13 +0400
committerWolfram Sang <wsa@the-dreams.de>2014-11-23 17:27:48 +0100
commitb76911d2fe1462e1fc7c449e3e6aef76331e816e (patch)
tree761eb0013ee5b0d8e0f1e2438a19bd153058ec81 /drivers/i2c
parent0f5768bf894f853c21e5f336b5f495599172f39b (diff)
downloadlinux-b76911d2fe1462e1fc7c449e3e6aef76331e816e.tar.bz2
i2c: omap: don't reset controller if Arbitration Lost detected
Arbitration Lost is an expected situation in a multimaster environment. I2C controller (IP) correctly detect and report AL. The only one visible reason for resetting IP in the AL case is to avoid advisory 1.94 (omap3) and errata i595 (omap4): "I2C: After an Arbitration is Lost the Module Incorrectly Starts the Next Transfer". Errata workaround states: "The MST and STT bits inside I2C_CON should be set to 1 at the same moment (avoid setting the MST bit to 1 while STT = 0)." The driver never set MST and STT bits separately and doesn't create condition for errata. So the reset is not necessary. Also corrected return value for AL to -EAGAIN. Tested on Beagleboard XM C. Tested on BBB and AM437x Starter Kit by Felipe Balbi. Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com> Tested-by: Felipe Balbi <balbi@ti.com> Reviewed-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-omap.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 4426e9970e8f..b70270d8efdc 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -703,13 +703,15 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
return 0;
/* We have an error */
- if (dev->cmd_err & (OMAP_I2C_STAT_AL | OMAP_I2C_STAT_ROVR |
- OMAP_I2C_STAT_XUDF)) {
+ if (dev->cmd_err & (OMAP_I2C_STAT_ROVR | OMAP_I2C_STAT_XUDF)) {
omap_i2c_reset(dev);
__omap_i2c_init(dev);
return -EIO;
}
+ if (dev->cmd_err & OMAP_I2C_STAT_AL)
+ return -EAGAIN;
+
if (dev->cmd_err & OMAP_I2C_STAT_NACK) {
if (msg->flags & I2C_M_IGNORE_NAK)
return 0;