On Saturday 10 March 2018 03:53 AM, Enric Balletbo i Serra wrote:
From: zain wang <w...@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.
Reviewed-by: Archit Taneja <arch...@codeaurora.org> Thanks, Archit
Cc: Stéphane Marchesin <marc...@chromium.org> Signed-off-by: zain wang <w...@rock-chips.com> Signed-off-by: Sean Paul <seanp...@chromium.org> Signed-off-by: Thierry Escande <thierry.esca...@collabora.com> Signed-off-by: Enric Balletbo i Serra <enric.balle...@collabora.com> Tested-by: Marek Szyprowski <m.szyprow...@samsung.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 c81733b8185e..92fb9a072cb6 100644 --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c @@ -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;
