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Commit dca0be0d authored by Alex Deucher's avatar Alex Deucher Committed by Christian König
Browse files

drm/radeon: clarify special handling in i2c over aux 



We need a special packet for the start and end of the
transaction.

Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
Acked-by: default avatarChristian König <christian.koenig@amd.com>
parent 6f50e075

drivers/gpu/drm/radeon/atombios_dp.c

+16 −20
Original line number Diff line number Diff line
@@ -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);