| Message ID | 20170310043305.17216-20-seanpaul@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 10.03.2017 05:32, Sean Paul wrote: > 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> > --- > drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c > index f3eea7636a2e..048b6f7c9b6e 100644 > --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c > +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c > @@ -1172,6 +1172,15 @@ 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; > + } > + With previous patch analogix_dp_set_bridge will be repeated even if hpd is low, is it desired behavior? Regards Andrzej > ret = analogix_dp_commit(dp); > if (ret) > goto out_dp_init;
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c index f3eea7636a2e..048b6f7c9b6e 100644 --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c @@ -1172,6 +1172,15 @@ 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;