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Commit 9f68ef90 authored by Nicholas Mc Guire's avatar Nicholas Mc Guire Committed by Rob Clark
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drm/msm: fixup wait_for_completion_timeout handling 



wait_for_completion_timeout return >= 0 but never negative so the check
logic looks inconsistent. Further the return value of
wait_for_completion_timeout was being passed up the call chain but the
x call sites as drm_dp_i2c_do_msg()/drm_dp_dpcd_access() check for < 0
thus timeout was being treated as success case.

<snip> drivers/gpu/drm/drm_dp_helper.c:drm_dp_i2c_do_msg()
                mutex_lock(&aux->hw_mutex);
                ret = aux->transfer(aux, msg);
                mutex_unlock(&aux->hw_mutex);
                if (ret < 0) {
<snip>
logic in edp_aux_transfer() seems incorrect as it could return 0 (timeout)
but checks of <= 0 to indicate error so the return probably should be
-ETIMEDOUT in case wait_for_completion_timeout returns 0 (timeout
occurred).

Signed-off-by: default avatarNicholas Mc Guire <hofrat@osadl.org>
Signed-off-by: default avatarRob Clark <robdclark@gmail.com>
parent e5989ee1

drivers/gpu/drm/msm/edp/edp_aux.c

+5 −3
Original line number Diff line number Diff line
@@ -119,6 +119,7 @@ ssize_t edp_aux_transfer(struct drm_dp_aux *drm_aux, struct drm_dp_aux_msg *msg) 
{

	struct edp_aux *aux = to_edp_aux(drm_aux);

	ssize_t ret;

	unsigned long time_left;

	bool native = msg->request & (DP_AUX_NATIVE_WRITE & DP_AUX_NATIVE_READ);

	bool read = msg->request & (DP_AUX_I2C_READ & DP_AUX_NATIVE_READ);
@@ -147,15 +148,16 @@ ssize_t edp_aux_transfer(struct drm_dp_aux *drm_aux, struct drm_dp_aux_msg *msg) 
		goto unlock_exit;



	DBG("wait_for_completion");

	ret = wait_for_completion_timeout(&aux->msg_comp, 300);

	if (ret <= 0) {

	time_left = wait_for_completion_timeout(&aux->msg_comp, 300);

	if (!time_left) {

		/*

		 * Clear GO and reset AUX channel

		 * to cancel the current transaction.

		 */

		edp_write(aux->base + REG_EDP_AUX_TRANS_CTRL, 0);

		msm_edp_aux_ctrl(aux, 1);

		pr_err("%s: aux timeout, %zd\n", __func__, ret);

		pr_err("%s: aux timeout, %lu\n", __func__, time_left);

		ret = -ETIMEDOUT;

		goto unlock_exit;

	}

	DBG("completion");