On Sat, Sep 14, 2024 at 10:12:29PM GMT, Cristian Ciocaltea wrote: > Hi Maxime, > > On 9/9/24 6:13 PM, Maxime Ripard wrote: > > Hi, > > > > On Fri, Sep 06, 2024 at 04:17:40AM GMT, Cristian Ciocaltea wrote: > >> +static enum drm_connector_status > >> +dw_hdmi_qp_bridge_detect(struct drm_bridge *bridge) > >> +{ > >> + struct dw_hdmi_qp *hdmi = bridge->driver_private; > >> + enum drm_connector_status status; > >> + > >> + status = hdmi->phy.ops->read_hpd(hdmi, hdmi->phy.data); > >> + > >> + dev_dbg(hdmi->dev, "%s conn=%d scramb=%d\n", __func__, > >> + status == connector_status_connected, hdmi->scramb_enabled); > >> + > >> + if (hdmi->scramb_enabled) { > >> + cancel_delayed_work_sync(&hdmi->scramb_work); > >> + > >> + if (status == connector_status_connected) > >> + dw_hdmi_qp_check_and_set_scramb(hdmi); > >> + } > >> + > >> + return status; > >> +} > > > > Unfortunately, that won't work. The HDMI Spec has (HDMI 2.0, Section > > 6.1.3.1 - Scrambling Control): > > > > The minimum time period between the write to the Scrambling_Enable bit, > > and the transmission of a scrambled video signal is not specified; > > however the Source shall not begin transmission of a scrambled video > > signal before writing a 1 to the Scrambling_Enable bit. The maximum time > > period between the write to the Scrambling_Enable bit and the > > transmission of a scrambled video signal shall be 100 ms. > > > > So you need to disable the output and enable it again. > > > > vc4 does just that, you can have a look here: > > https://elixir.bootlin.com/linux/v6.10.9/source/drivers/gpu/drm/vc4/vc4_hdmi.c#L410 > > Thanks for all the details and references! > > Unfortunately I had to drop the scrambling setup for now [1], as I > encountered some issues while attempting to get this implemented as > suggested. Will get back to this and submit it separately when done. Yeah, I think that's the best way forward for now :) Maxime
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