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drm/i915/dp: add native aux defer retry limit

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Retrying indefinitely places too much trust on the aux implementation of
the sink devices.

Reported-by: Daniel Martin <consume.noise@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=71267
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Cc: stable@vger.kernel.org
Tested-by: Theodore Ts'o <tytso@mit.edu>
Tested-by: Sree Harsha Totakura <freedesktop@h.totakura.in>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Jani Nikula 2014-02-11 11:52:05 +02:00 committed by Daniel Vetter
parent 04eada25d1
commit f51a44b9a6
1 changed files with 11 additions and 4 deletions
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15
drivers/gpu/drm/i915/intel_dp.c
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@ -537,6 +537,7 @@ intel_dp_aux_native_write(struct intel_dp *intel_dp,
uint8_t msg[20];
int msg_bytes;
uint8_t ack;
int retry;
if (WARN_ON(send_bytes > 16))
return -E2BIG;
@ -548,19 +549,21 @@ intel_dp_aux_native_write(struct intel_dp *intel_dp,
msg[3] = send_bytes - 1;
memcpy(&msg[4], send, send_bytes);
msg_bytes = send_bytes + 4;
for (;;) {
for (retry = 0; retry < 7; retry++) {
ret = intel_dp_aux_ch(intel_dp, msg, msg_bytes, &ack, 1);
if (ret < 0)
return ret;
ack >>= 4;
if ((ack & DP_AUX_NATIVE_REPLY_MASK) == DP_AUX_NATIVE_REPLY_ACK)
break;
return send_bytes;
else if ((ack & DP_AUX_NATIVE_REPLY_MASK) == DP_AUX_NATIVE_REPLY_DEFER)
usleep_range(400, 500);
else
return -EIO;
}
return send_bytes;
DRM_ERROR("too many retries, giving up\n");
return -EIO;
}
/* Write a single byte to the aux channel in native mode */
@ -582,6 +585,7 @@ intel_dp_aux_native_read(struct intel_dp *intel_dp,
int reply_bytes;
uint8_t ack;
int ret;
int retry;
if (WARN_ON(recv_bytes > 19))
return -E2BIG;
@ -595,7 +599,7 @@ intel_dp_aux_native_read(struct intel_dp *intel_dp,
msg_bytes = 4;
reply_bytes = recv_bytes + 1;
for (;;) {
for (retry = 0; retry < 7; retry++) {
ret = intel_dp_aux_ch(intel_dp, msg, msg_bytes,
reply, reply_bytes);
if (ret == 0)
@ -612,6 +616,9 @@ intel_dp_aux_native_read(struct intel_dp *intel_dp,
else
return -EIO;
}
DRM_ERROR("too many retries, giving up\n");
return -EIO;
}
static int