diff options
| author | Tali Perry <tali.perry1@gmail.com> | 2020-09-20 23:48:09 +0300 |
|---|---|---|
| committer | Wolfram Sang <wsa@kernel.org> | 2020-09-27 20:05:27 +0200 |
| commit | 8947efc077168c53b84d039881a7c967086a248a (patch) | |
| tree | 97fc351bbc8e6d15faf388ebc072c2fab563baee /drivers/i2c | |
| parent | a2bd970aa62f2f7f80fd0d212b1d4ccea5df4aed (diff) | |
i2c: npcm7xx: Clear LAST bit after a failed transaction.
Due to a HW issue, in some scenarios the LAST bit might remain set.
This will cause an unexpected NACK after reading 16 bytes on the next
read.
Example: if user tries to read from a missing device, get a NACK,
then if the next command is a long read ( > 16 bytes),
the master will stop reading after 16 bytes.
To solve this, if a command fails, check if LAST bit is still
set. If it does, reset the module.
Fixes: 56a1485b102e (i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver)
Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-npcm7xx.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-npcm7xx.c b/drivers/i2c/busses/i2c-npcm7xx.c index dfcf04e1967f..2ad166355ec9 100644 --- a/drivers/i2c/busses/i2c-npcm7xx.c +++ b/drivers/i2c/busses/i2c-npcm7xx.c @@ -2163,6 +2163,15 @@ static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, if (bus->cmd_err == -EAGAIN) ret = i2c_recover_bus(adap); + /* + * After any type of error, check if LAST bit is still set, + * due to a HW issue. + * It cannot be cleared without resetting the module. + */ + if (bus->cmd_err && + (NPCM_I2CRXF_CTL_LAST_PEC & ioread8(bus->reg + NPCM_I2CRXF_CTL))) + npcm_i2c_reset(bus); + #if IS_ENABLED(CONFIG_I2C_SLAVE) /* reenable slave if it was enabled */ if (bus->slave) |