We need a special packet for the start and end of the transaction.
Signed-off-by: Alex Deucher alexander.deucher@amd.com --- drivers/gpu/drm/radeon/atombios_dp.c | 36 ++++++++++++++++-------------------- 1 file changed, 16 insertions(+), 20 deletions(-)
diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c index 88d399c..23189b7 100644 --- a/drivers/gpu/drm/radeon/atombios_dp.c +++ b/drivers/gpu/drm/radeon/atombios_dp.c @@ -246,34 +246,30 @@ int radeon_dp_i2c_aux_ch(struct i2c_adapter *adapter, int mode, int ret; u8 ack;
- /* Set up the command byte */ - if (mode & MODE_I2C_READ) - msg[2] = DP_AUX_I2C_READ << 4; - else - msg[2] = DP_AUX_I2C_WRITE << 4; - - if (!(mode & MODE_I2C_STOP)) - msg[2] |= DP_AUX_I2C_MOT << 4; - + /* Set up the address */ msg[0] = address; msg[1] = address >> 8;
- switch (mode) { - case MODE_I2C_WRITE: + /* Set up the command byte */ + if (mode & MODE_I2C_READ) { + msg[2] = DP_AUX_I2C_READ << 4; + msg_bytes = 4; + msg[3] = msg_bytes << 4; + } else { + msg[2] = DP_AUX_I2C_WRITE << 4; msg_bytes = 5; msg[3] = msg_bytes << 4; msg[4] = write_byte; - break; - case MODE_I2C_READ: - msg_bytes = 4; - msg[3] = msg_bytes << 4; - break; - default: - msg_bytes = 4; - msg[3] = 3 << 4; - break; }
+ /* special handling for start/stop */ + if (mode & (MODE_I2C_START | MODE_I2C_STOP)) + msg[3] = 3 << 4; + + /* Set MOT bit for all but stop */ + if ((mode & MODE_I2C_STOP) == 0) + msg[2] |= DP_AUX_I2C_MOT << 4; + for (retry = 0; retry < 7; retry++) { ret = radeon_process_aux_ch(auxch, msg, msg_bytes, reply, reply_bytes, 0, &ack);