On Thu, Nov 25, 2021 at 04:42:25PM +0100, Jacopo Mondi wrote: > Hello > G > On Thu, Nov 25, 2021 at 09:23:41AM +0200, Sakari Ailus wrote: > > Hi Laurent, > > > > On Thu, Nov 25, 2021 at 12:12:18AM +0200, Laurent Pinchart wrote: > > > Hi Adam, > > > > > > (CC'ing Sakari) > > > > > > On Wed, Nov 24, 2021 at 03:16:57PM -0600, Adam Ford wrote: > > > > I am trying to use an OV5640 camera sensor that I've used on both an > > > > i.MX6Q and an i.MX8M Mini (with good success) on an RZ/G2[MNH] board > > > > connected to the 2-lane CSI interface. > > > > > > > > I can get the media-ctl to show the routings, and sometimes I can get > > > > streaming. Often, I get a timeout: > > > > > > > > rcar-csi2 fea80000.csi2: Timeout waiting for LP-11 state > > > > > > > > Looking at the various mailing list e-mails for the LP-11, it's > > > > unclear to me if the timeout is caused by the sensor not doing > > > > something correctly or the CSI2 misbehaving. > > > > > > Before transitioning to the high speed (HS) mode, the D-PHY transmitter > > > must drive the lane in the LP-11 state. This is the idle state of the > > > lane when powered up and when not in the ultra low-power state (ULPS). > > > The transition to HS mode on the receiver side involves observing the > > > LP-11 state. Many D-PHY RX require configuring the PHY when the lane is > > > in LP-11 state, and only then starting the sensor to transition to HS. > > > This requires powering up the D-PHY TX and going to idle mode, which > > > most sensors support. As we're deprecating the .s_power() subdev > > > operation, however, we have no way to power up the sensor without > > > starting it before the D-PHY RX gets configured. > > > > That's not true anymore. Please see: > > > > <URL:https://hverkuil.home.xs4all.nl/spec/driver-api/tx-rx.html#lp-11-and-lp-111-modes> > > > > Not all sensors can do this without tricks though. > > > > > > > > In some cases, the D-PHY RX can handle the power up sequence > > > automatically. They can be fully configured (from a software point of > > > view) while the lane is in the power down state LP-00, and they then > > > handle the transition to the stop state LP-11 and to the HS mode > > > automatically. This isn't true for all receivers, some need software > > > configuration after the data lane reaches the LP-11 state and before it > > > transitions to HS mode. According to the documentation, the R-Car CSI-2 > > > receiver requires software intervention between LP-11 and HS mode at > > > least on V3M and E3. There's also a software configuration step on H3, > > > M3N, V3H and V3U, but there's a chance that one could possibly be > > > bypassed. > > > > > > > I was hoping someone might have some suggestions of things I can try. > > > > > > I would first try to power up the sensor at probe time and keep it power > > > forever, to see if it solves your issue. If it does, then introducing a > > > CSI-2-specific subdev operation to power up the sensor (or officially > > > de-deprecating .s_power() for this use case) could be an option to fix > > > the issue properly. > > What about .pre_streamon video op ? > Should it fit here ? That's its first use case but there can be others. -- Sakari Ailus
