revert r273728 and parts of r306589, iicbus no-stop by default feature

Since drm2 removal, there has not been any consumer of the feature in the
tree.  I am also unaware of any out-of-tree consumer.
More importantly, the feature has been broken from the very start, both
before and after r306589, because the ivar was set on a device that does
not support it and it was read from another device that also does not
support it.

A bus-wide no-stop flag cannot be implemented as an ivar as iicbus
attaches as a child of various drivers.  Implementing the ivar in each
and every I2C driver is just impractical.

If we ever want to implement this feature properly, then probably the
easiest way to do it would be via a flag in the softc of iicbus.
In fact, we might have to do that in the stable branches if we want to
fix the code for them.

Reported by:	ian (long time ago)
MFC after:	1 month (maybe)
X-MFC-note:	cannot just merge the change, must keep drm2 happy

3 files changed, 5 insertions, 16 deletions

diff --git a/sys/dev/iicbus/iicbus.c b/sys/dev/iicbus/iicbus.c
index de30c0168901..0795b99dcd69 100644
--- a/sys/dev/iicbus/iicbus.c
+++ b/sys/dev/iicbus/iicbus.c
@@ -194,9 +194,6 @@ iicbus_read_ivar(device_t bus, device_t child, int which, uintptr_t *result)
 	case IICBUS_IVAR_ADDR:
 		*result = devi->addr;
 		break;
-	case IICBUS_IVAR_NOSTOP:
-		*result = devi->nostop;
-		break;
 	}
 	return (0);
 }
@@ -213,9 +210,6 @@ iicbus_write_ivar(device_t bus, device_t child, int which, uintptr_t value)
 		if (devi->addr != 0)
 			return (EINVAL);
 		devi->addr = value;
-	case IICBUS_IVAR_NOSTOP:
-		devi->nostop = value;
-		break;
 	}
 	return (0);
 }
diff --git a/sys/dev/iicbus/iicbus.h b/sys/dev/iicbus/iicbus.h
index 018b25113d22..ec033d708aaa 100644
--- a/sys/dev/iicbus/iicbus.h
+++ b/sys/dev/iicbus/iicbus.h
@@ -54,19 +54,16 @@ struct iicbus_ivar
 {
 	uint32_t	addr;
 	struct resource_list	rl;
-	bool		nostop;
 };
 
 enum {
-	IICBUS_IVAR_ADDR,		/* Address or base address */
-	IICBUS_IVAR_NOSTOP,		/* nostop defaults */
+	IICBUS_IVAR_ADDR		/* Address or base address */
 };
 
 #define IICBUS_ACCESSOR(A, B, T)					\
 	__BUS_ACCESSOR(iicbus, A, IICBUS, B, T)
 	
 IICBUS_ACCESSOR(addr,		ADDR,		uint32_t)
-IICBUS_ACCESSOR(nostop,		NOSTOP,		bool)
 
 #define	IICBUS_LOCK(sc)			mtx_lock(&(sc)->lock)
 #define	IICBUS_UNLOCK(sc)      		mtx_unlock(&(sc)->lock)
diff --git a/sys/dev/iicbus/iiconf.c b/sys/dev/iicbus/iiconf.c
index 916baf2dba0c..94ce3d18c70f 100644
--- a/sys/dev/iicbus/iiconf.c
+++ b/sys/dev/iicbus/iiconf.c
@@ -427,7 +427,7 @@ iicbus_transfer_gen(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
 {
 	int i, error, lenread, lenwrote, nkid, rpstart, addr;
 	device_t *children, bus;
-	bool nostop, started;
+	bool started;
 
 	if ((error = device_get_children(dev, &children, &nkid)) != 0)
 		return (IIC_ERESOURCE);
@@ -438,7 +438,6 @@ iicbus_transfer_gen(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
 	bus = children[0];
 	rpstart = 0;
 	free(children, M_TEMP);
-	nostop = iicbus_get_nostop(dev);
 	started = false;
 	for (i = 0, error = 0; i < nmsgs && error == 0; i++) {
 		addr = msgs[i].slave;
@@ -466,12 +465,11 @@ iicbus_transfer_gen(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
 		if (error != 0)
 			break;
 
-		if ((msgs[i].flags & IIC_M_NOSTOP) != 0 ||
-		    (nostop && i + 1 < nmsgs)) {
-			rpstart = 1;	/* Next message gets repeated start */
-		} else {
+		if (!(msgs[i].flags & IIC_M_NOSTOP)) {
 			rpstart = 0;
 			iicbus_stop(bus);
+		} else {
+			rpstart = 1;	/* Next message gets repeated start */
 		}
 	}
 	if (error != 0 && started)