From 4f734a3a0434ef2bb668716ff28ba677fa0dc929 Mon Sep 17 00:00:00 2001 From: Alexander Kochetkov Date: Sat, 22 Nov 2014 23:47:14 +0400 Subject: [PATCH] i2c: omap: add notes related to i2c multimaster mode No functional changes. Signed-off-by: Alexander Kochetkov Reviewed-by: Felipe Balbi Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-omap.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index b70270d8efdc..9f5b57a50c54 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -299,6 +299,12 @@ static void __omap_i2c_init(struct omap_i2c_dev *dev) /* Take the I2C module out of reset: */ omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN); + /* + * NOTE: right after setting CON_EN, STAT_BB could be 0 while the + * bus is busy. It will be changed to 1 on the next IP FCLK clock. + * udelay(1) will be enough to fix that. + */ + /* * Don't write to this register if the IE state is 0 as it can * cause deadlock. @@ -660,7 +666,11 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap, if (!dev->b_hw && stop) w |= OMAP_I2C_CON_STP; - + /* + * NOTE: STAT_BB bit could became 1 here if another master occupy + * the bus. IP successfully complete transfer when the bus will be + * free again (BB reset to 0). + */ omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, w); /* -- 2.20.1