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Commit 6375bda0 authored by Alex Deucher's avatar Alex Deucher Committed by Dave Airlie
Browse files

drm/radeon/kms: add retry limits for native DP aux defer 



The previous code could potentially loop forever.  Limit
the number of DP aux defer retries to 4 for native aux
transactions, same as i2c over aux transactions.

Noticed by: Brad Campbell <lists2009@fnarfbargle.com>

Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
Cc: Brad Campbell <lists2009@fnarfbargle.com>
Cc: stable@kernel.org
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent 109bc10d

drivers/gpu/drm/radeon/atombios_dp.c

+8 −4
Original line number Diff line number Diff line
@@ -115,6 +115,7 @@ static int radeon_dp_aux_native_write(struct radeon_connector *radeon_connector, 
	u8 msg[20];

	int msg_bytes = send_bytes + 4;

	u8 ack;

	unsigned retry;



	if (send_bytes > 16)

		return -1;
@@ -125,20 +126,20 @@ static int radeon_dp_aux_native_write(struct radeon_connector *radeon_connector, 
	msg[3] = (msg_bytes << 4) | (send_bytes - 1);

	memcpy(&msg[4], send, send_bytes);



	while (1) {

	for (retry = 0; retry < 4; retry++) {

		ret = radeon_process_aux_ch(dig_connector->dp_i2c_bus,

					    msg, msg_bytes, NULL, 0, delay, &ack);

		if (ret < 0)

			return ret;

		if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_ACK)

			break;

			return send_bytes;

		else if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_DEFER)

			udelay(400);

		else

			return -EIO;

	}



	return send_bytes;

	return -EIO;

}



static int radeon_dp_aux_native_read(struct radeon_connector *radeon_connector,
@@ -149,13 +150,14 @@ static int radeon_dp_aux_native_read(struct radeon_connector *radeon_connector, 
	int msg_bytes = 4;

	u8 ack;

	int ret;

	unsigned retry;



	msg[0] = address;

	msg[1] = address >> 8;

	msg[2] = AUX_NATIVE_READ << 4;

	msg[3] = (msg_bytes << 4) | (recv_bytes - 1);



	while (1) {

	for (retry = 0; retry < 4; retry++) {

		ret = radeon_process_aux_ch(dig_connector->dp_i2c_bus,

					    msg, msg_bytes, recv, recv_bytes, delay, &ack);

		if (ret < 0)
@@ -169,6 +171,8 @@ static int radeon_dp_aux_native_read(struct radeon_connector *radeon_connector, 
		else

			return -EIO;

	}



	return -EIO;

}



static void radeon_write_dpcd_reg(struct radeon_connector *radeon_connector,