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authorJani Nikula <jani.nikula@intel.com>2014-02-11 11:52:05 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-03-06 22:06:31 -0800
commit87c3c227f580e2965feceae5f8973e9a38644963 (patch)
tree28ac1df856084271ce9ed2b344e0a42726277ece
parentaf42ee9f6b2028c6d77c1173fcf24fe0c4480b1f (diff)
drm/i915/dp: add native aux defer retry limit
commit f51a44b9a6c4982cc25bfb3727de9bb893621ebc upstream. 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> 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/gpu/drm/i915/intel_dp.c15
1 files changed, 11 insertions, 4 deletions
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 24cede7bcb62..3e1b348de244 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -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;
@@ -548,18 +549,20 @@ 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;
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)
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 */
@@ -581,6 +584,7 @@ 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;
@@ -594,7 +598,7 @@ 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)
@@ -611,6 +615,9 @@ 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