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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>
This commit is contained in:
Alex Deucher 2011-10-03 09:13:46 -04:00 committed by Dave Airlie
parent 109bc10d30
commit 6375bda073
1 changed files with 8 additions and 4 deletions
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12
drivers/gpu/drm/radeon/atombios_dp.c
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@ -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,