From b395ba21699dbbca2dbf05833a71f5fbf5245a3f Mon Sep 17 00:00:00 2001 From: Wolfram Sang Date: Mon, 19 Jun 2017 23:41:46 +0200 Subject: [PATCH] i2c: rcar: document HW incapabilities Add recent findings (IGNORE_NAK) and document in a bit more detail why the feature is not possible. Signed-off-by: Wolfram Sang Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-rcar.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c index 214a71cb6442..030952e2ddc7 100644 --- a/drivers/i2c/busses/i2c-rcar.c +++ b/drivers/i2c/busses/i2c-rcar.c @@ -783,7 +783,12 @@ static int rcar_unreg_slave(struct i2c_client *slave) static u32 rcar_i2c_func(struct i2c_adapter *adap) { - /* This HW can't do SMBUS_QUICK and NOSTART */ + /* + * This HW can't do: + * I2C_SMBUS_QUICK (setting FSB during START didn't work) + * I2C_M_NOSTART (automatically sends address after START) + * I2C_M_IGNORE_NAK (automatically sends STOP after NAK) + */ return I2C_FUNC_I2C | I2C_FUNC_SLAVE | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK); } -- 2.45.2