06.08.2020 03:47, Sowjanya Komatineni пишет: > > On 8/5/20 11:06 AM, Sowjanya Komatineni wrote: >> >> On 8/5/20 10:46 AM, Sowjanya Komatineni wrote: >>> >>> On 8/5/20 10:34 AM, Dmitry Osipenko wrote: >>>> 05.08.2020 20:29, Sowjanya Komatineni пишет: >>>> ... >>>>> UART_FST_MIPI_CAL is the clock used for calibration logic which is FSM >>>>> that goes thru sequence codes and when done waits for pads to be in >>>>> LP-11 to apply results. >>>>> >>>>> MIPI_CLK is controller gate clock which is also need to be kept >>>>> enabled >>>>> as incase if it sees LP-11 it updates registers so its recommended to >>>>> have this clock enabled. >>>>> >>>>> We can cancel_calibration() in CSI only when csi/sensor stream on >>>>> fails >>>>> and in which case there will be no LP-11 so we can unconditionally >>>>> disable MIPI_CLK. >>>>> >>>> There is no guarantee that the fail comes before the LP-11. For >>>> example, >>>> some odd camera driver may have a complicated enable sequence which may >>>> fail after enabling the hardware streaming. >>> >>> MIPI_CLK to keep enable is for calibration logic to update results, >>> but like I said calibration logic uses UART_FST_MIPI_CAL clock. So >>> even in case if fail happens from sensor after having pads in LP-11 >>> then, calibration logic will still be running but result update will >>> not happen with clock disabled. But HW will not stuck as this is >>> confirmed from HW designer. >> >> If LP-11 happens from sensor stream (followed by fail) and by that >> time if calibration FSM is done and if calibration logic sees LP-11 >> then results will be applied to pads. >> >> We did start of calibration before CSI stream so by the time we do >> sensor stream enable, calibration logic might have done with FSM and >> waiting for LP-11 >> >> Also if we see any special case, we always can use >> finish_calibration() instead of cancel_calibration() as well. Why not to do it right now? Then the code could look like this: src_subdev = tegra_channel_get_remote_source_subdev(chan); ret = v4l2_subdev_call(src_subdev, video, s_stream, true); err = tegra_mipi_finish_calibration(csi_chan->mipi); if (ret < 0 && ret != -ENOIOCTLCMD) goto err_disable_csi_stream; if (err < 0) dev_warn(csi_chan->csi->dev, "MIPI calibration failed: %d\n", err); >> finish_calibration() has extra 250ms wait time polling done bit and we >> can ignore its return code during fail pathway. >> > Confirmed from HW designer, calibration FSM to finish takes worst case > 72uS so by the time it gets to sensor stream it will be done its > sequence and will be waiting for DONE bit. > > So disabling MIPI CAL clock on sensor stream fails is safe. 72us is quite a lot of time, what will happen if LP-11 happens before FSM finished calibration? Maybe the finish_calibration() needs to split into two parts: 1. wait for CAL_STATUS_ACTIVE before enabling sensor 2. wait for CAL_STATUS_DONE after enabling sensor
