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Commit de5f4d65 authored by Ajay Singh Parmar's avatar Ajay Singh Parmar
Browse files

disp: msm: dp: add support for lane count reduction 



Add support for lane count reduction as per the new requirements
for DP 1.4a during link training 2.

CRs-Fixed: 2458753
Change-Id: I58c9b6101338e8a1d1b4e3dec80f8fdf2a25ae5b
Signed-off-by: default avatarAjay Singh Parmar <aparmar@codeaurora.org>
parent c44165dd

msm/dp/dp_ctrl.c

+41 −2
Original line number Diff line number Diff line
@@ -71,6 +71,8 @@ struct dp_ctrl_private { 


	atomic_t aborted;



	u8 initial_lane_count;



	u32 vic;

	u32 stream_count;

	struct dp_mst_channel_info mst_ch_info;
@@ -254,6 +256,32 @@ static int dp_ctrl_read_link_status(struct dp_ctrl_private *ctrl, 
	return ret;

}



static int dp_ctrl_lane_count_down_shift(struct dp_ctrl_private *ctrl)

{

	int ret = -EAGAIN;

	u8 lanes = ctrl->link->link_params.lane_count;



	if (ctrl->panel->link_info.revision != 0x14)

		return -EINVAL;



	switch (lanes) {

	case 4:

		ctrl->link->link_params.lane_count = 2;

		break;

	case 2:

		ctrl->link->link_params.lane_count = 1;

		break;

	default:

		if (lanes != ctrl->initial_lane_count)

			ret = -EINVAL;

		break;

	}



	pr_debug("new lane count=%d\n", ctrl->link->link_params.lane_count);



	return ret;

}



static int dp_ctrl_link_train_1(struct dp_ctrl_private *ctrl)

{

	int tries, old_v_level, ret = 0;
@@ -416,12 +444,19 @@ static int dp_ctrl_link_training_2(struct dp_ctrl_private *ctrl) 
		if (ret)

			break;



		/* check if CR bits still remain set */

		if (!drm_dp_clock_recovery_ok(link_status,

			ctrl->link->link_params.lane_count)) {

			ret = -EINVAL;

			break;

		}



		if (drm_dp_channel_eq_ok(link_status,

			ctrl->link->link_params.lane_count))

			break;



		if (tries > maximum_retries) {

			ret = -ETIMEDOUT;

			ret = dp_ctrl_lane_count_down_shift(ctrl);

			break;

		}

		tries++;
@@ -604,6 +639,7 @@ static int dp_ctrl_link_setup(struct dp_ctrl_private *ctrl, bool shallow) 
		if (!link_train_max_retries-- || atomic_read(&ctrl->aborted))

			break;



		if (rc != -EAGAIN)

			dp_ctrl_link_rate_down_shift(ctrl);



		dp_ctrl_configure_source_link_params(ctrl, false);
@@ -1176,6 +1212,9 @@ static int dp_ctrl_on(struct dp_ctrl *dp_ctrl, bool mst_mode, 
		ctrl->link->link_params.bw_code,

		ctrl->link->link_params.lane_count);



	/* backup initial lane count */

	ctrl->initial_lane_count = ctrl->link->link_params.lane_count;



	rc = dp_ctrl_link_setup(ctrl, shallow);

	ctrl->power_on = true;

end: