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drm/bridge: analogix_dp: Wait for HPD signal before configuring link

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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: zain wang <wzz@rock-chips.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180423105003.9004-6-enric.balletbo@collabora.com
This commit is contained in:
zain wang 2018-04-23 12:49:41 +02:00 committed by Andrzej Hajda
parent 8a335736f9
commit 7f6414143a
1 changed files with 11 additions and 0 deletions
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11
drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
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@ -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;