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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: Alex Deucher <alexander.deucher@amd.com> Cc: Brad Campbell <lists2009@fnarfbargle.com> Cc: stable@kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
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109bc10d30
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6375bda073
1 changed files with 8 additions and 4 deletions
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@ -115,6 +115,7 @@ static int radeon_dp_aux_native_write(struct radeon_connector *radeon_connector,
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u8 msg[20];
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int msg_bytes = send_bytes + 4;
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u8 ack;
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unsigned retry;
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if (send_bytes > 16)
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return -1;
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@ -125,20 +126,20 @@ static int radeon_dp_aux_native_write(struct radeon_connector *radeon_connector,
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msg[3] = (msg_bytes << 4) | (send_bytes - 1);
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memcpy(&msg[4], send, send_bytes);
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while (1) {
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for (retry = 0; retry < 4; retry++) {
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ret = radeon_process_aux_ch(dig_connector->dp_i2c_bus,
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msg, msg_bytes, NULL, 0, delay, &ack);
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if (ret < 0)
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return ret;
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if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_ACK)
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break;
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return send_bytes;
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else if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_DEFER)
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udelay(400);
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else
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return -EIO;
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}
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return send_bytes;
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return -EIO;
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}
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static int radeon_dp_aux_native_read(struct radeon_connector *radeon_connector,
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@ -149,13 +150,14 @@ static int radeon_dp_aux_native_read(struct radeon_connector *radeon_connector,
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int msg_bytes = 4;
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u8 ack;
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int ret;
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unsigned retry;
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msg[0] = address;
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msg[1] = address >> 8;
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msg[2] = AUX_NATIVE_READ << 4;
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msg[3] = (msg_bytes << 4) | (recv_bytes - 1);
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while (1) {
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for (retry = 0; retry < 4; retry++) {
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ret = radeon_process_aux_ch(dig_connector->dp_i2c_bus,
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msg, msg_bytes, recv, recv_bytes, delay, &ack);
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if (ret < 0)
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@ -169,6 +171,8 @@ static int radeon_dp_aux_native_read(struct radeon_connector *radeon_connector,
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else
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return -EIO;
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}
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return -EIO;
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}
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static void radeon_write_dpcd_reg(struct radeon_connector *radeon_connector,
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