Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit f51a44b9 authored by Jani Nikula's avatar Jani Nikula Committed by Daniel Vetter
Browse files

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



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

Reported-by: default avatarDaniel Martin <consume.noise@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=71267


Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
Cc: stable@vger.kernel.org
Tested-by: default avatarTheodore Ts'o <tytso@mit.edu>
Tested-by: default avatarSree Harsha Totakura <freedesktop@h.totakura.in>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 04eada25

drivers/gpu/drm/i915/intel_dp.c

+11 −4
Original line number Diff line number Diff line
@@ -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