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Commit 7f641414 authored by zain wang's avatar zain wang Committed by Andrzej Hajda
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drm/bridge: analogix_dp: Wait for HPD signal before configuring link 



According to DP spec v1.3 chap 3.5.1.2 Link Training, Link Policy Maker
must first detect that the HPD signal is asserted high by the Downstream
Device before establishing a link with it.

Cc: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: default avatarzain wang <wzz@rock-chips.com>
Signed-off-by: default avatarSean Paul <seanpaul@chromium.org>
Signed-off-by: default avatarThierry Escande <thierry.escande@collabora.com>
Signed-off-by: default avatarEnric Balletbo i Serra <enric.balletbo@collabora.com>
Tested-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: default avatarArchit Taneja <architt@codeaurora.org>
Signed-off-by: default avatarAndrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180423105003.9004-6-enric.balletbo@collabora.com
parent 8a335736

drivers/gpu/drm/bridge/analogix/analogix_dp_core.c

+11 −0
Original line number Diff line number Diff line
@@ -1169,6 +1169,17 @@ static int analogix_dp_set_bridge(struct analogix_dp_device *dp) 
	if (ret)

		goto out_dp_init;



	/*

	 * According to DP spec v1.3 chap 3.5.1.2 Link Training,

	 * We should first make sure the HPD signal is asserted high by device

	 * when we want to establish a link with it.

	 */

	ret = analogix_dp_detect_hpd(dp);

	if (ret) {

		DRM_ERROR("failed to get hpd single ret = %d\n", ret);

		goto out_dp_init;

	}



	ret = analogix_dp_commit(dp);

	if (ret)

		goto out_dp_init;