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authorWolfram Sang <wsa+renesas@sang-engineering.com>2017-06-19 23:41:46 +0200
committerWolfram Sang <wsa@the-dreams.de>2017-06-23 20:30:46 +0200
commitb395ba21699dbbca2dbf05833a71f5fbf5245a3f (patch)
tree50dac13950fa19ad1bef6e9fbf640a43d09ec8c6 /drivers/i2c
parentf64622167f4aa5124fed264d481509829d34e126 (diff)
downloadlinux-b395ba21699dbbca2dbf05833a71f5fbf5245a3f.tar.bz2
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 <wsa+renesas@sang-engineering.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-rcar.c7
1 files changed, 6 insertions, 1 deletions
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);
}