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

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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
This commit is contained in:
Andriy Gapon 2019-05-29 09:08:20 +00:00
parent 93a2d4c92f
commit fec2f12ebd
3 changed files with 5 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
sys/dev/iicbus/iicbus.c
View File

@ -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);
}

5
sys/dev/iicbus/iicbus.h
View File

@ -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)

10
sys/dev/iicbus/iiconf.c
View File

@ -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)