From 6375bda073724ead7df08746866b724b1799a295 Mon Sep 17 00:00:00 2001 From: Alex Deucher Date: Mon, 3 Oct 2011 09:13:46 -0400 Subject: [PATCH] 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 Signed-off-by: Alex Deucher Cc: Brad Campbell Cc: stable@kernel.org Signed-off-by: Dave Airlie --- drivers/gpu/drm/radeon/atombios_dp.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c index f526fa7..4da2388 100644 --- a/drivers/gpu/drm/radeon/atombios_dp.c +++ b/drivers/gpu/drm/radeon/atombios_dp.c @@ -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, -- 2.7.4