On Fri, Oct 14, 2016 at 05:48:43PM +0200, Philipp Zabel wrote: > Am Samstag, den 08.10.2016, 02:16 +0300 schrieb Sakari Ailus: > > Hi Philipp, > > > > On Fri, Oct 07, 2016 at 06:00:49PM +0200, Philipp Zabel wrote: > > > In some cases, for example MIPI CSI-2 input on i.MX6, the sending and > > > receiving subdevice need to be prepared in lock-step before the actual > > > streaming can start. In the i.MX6 MIPI CSI-2 case, the sender needs to > > > put its MIPI CSI-2 transmitter lanes into stop state, and the receiver > > > needs to configure its D-PHY and detect the stop state on all active > > > lanes. Only then the sender can be enabled to stream data and the > > > receiver can lock its PLL to the clock lane. > > > > Is there a need to explicitly control this? Shouldn't this already be the > > case when the transmitting device is powered on and is not streaming? > > Even if the transmitter is expected to keep the lanes in this stop state > all the time while the subdevice is powered but not streaming, I still > have to wait for stop state detection before enabling the transmitter, > and only then enable the reciever. > I'll remove the prepare_streaming callback in the next version and > instead let the subdevices propagate s_stream upstream instead in the > next version.
Ack. As discussed, I'll provide a patch to document this behaviour on CSI-2. I believe the current drivers implicitly implement it but you're the first one to ask the question. :-) -- Sakari Ailus e-mail: sakari.ai...@iki.fi XMPP: sai...@retiisi.org.uk -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html