cam_da too noisy about SYNCHRONIZE CACHE

I have a Rpi3B which runs 15.0 on a Seagate USB-SATA gadget.

Every few hours usually around XX:X0:30 it spits out:

	Jan 27 00:40:30 rpi3b kernel: (da0:umass-sim0:0:0:0): MODE SENSE for CACHE page command failed.
	Jan 27 00:40:30 rpi3b kernel: (da0:umass-sim0:0:0:0): Mode page 8 missing, disabling SYNCHRONIZE CACHE
	Jan 27 00:40:30 rpi3b kernel: (da0:umass-sim0:0:0:0): Devices already quirked for NO_SYNC_CACHE, maybe remove quirk table

The relevant code in cam_da is:

			if (mark_bad) {
	bad:
				xpt_print(done_ccb->ccb_h.path,
				    "Mode page 8 missing, disabling SYNCHRONIZE CACHE\n");
				if (softc->quirks & DA_Q_NO_SYNC_CACHE)
					xpt_print(done_ccb->ccb_h.path,
	    "Devices already quirked for NO_SYNC_CACHE, maybe remove quirk table\n");
				softc->quirks |= DA_Q_NO_SYNC_CACHE;
				softc->disk->d_flags &= ~DISKFLAG_CANFLUSHCACHE;
			}

I can understand emitting the message the first time after a reboot, but
that program logic makes absolutely no sense to me ?

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