Messages in this thread Patch in this message | | | From | Thierry Escande <> | Subject | [PATCH v2 17/43] drm/bridge: analogix_dp: Wait for HPD signal before configuring link | Date | Fri, 26 Jan 2018 14:16:44 +0100 |
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From: zain wang <wzz@rock-chips.com>
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> --- drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c index ba2506e17f6d..c940a5bb80ac 100644 --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c @@ -1170,6 +1170,17 @@ 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; -- 2.14.1
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