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The latest changes to the MDIO code introduced a false-positive
warning with gcc-6 (possibly others):
drivers/net/phy/mdio-mux.c: In function 'mdio_mux_init':
drivers/net/phy/mdio-mux.c:188:3: error: 'parent_bus_node' may be used uninitialized in this function [-Werror=maybe-uninitialized]
It's easy to avoid the warning by making sure the parent_bus_node
is initialized in both cases at the start of the function, since
the later 'of_node_put()' call is also valid for a NULL pointer
argument.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: f20e6657a875 ("mdio: mux: Enhanced MDIO mux framework for integrated multiplexers")
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
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An integrated multiplexer uses same address space for
"muxed bus selection" and "generation of mdio transaction"
hence its good to register parent bus from mux driver.
Hence added a mechanism where mux driver could register a
parent bus and pass it down to framework via mdio_mux_init api.
Signed-off-by: Pramod Kumar <pramod.kumar@broadcom.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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MDIO devices can be stacked upon each other. The current code supports
two levels, which until recently has been enough for a DSA mdio bus on
top of another bus. Now we have hardware which has an MDIO mux in the
middle.
Define an MDIO MUTEX class with three levels.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Have mdio_alloc() create the array of interrupt numbers, and
initialize it to POLLING. This is what most MDIO drivers want, so
allowing code to be removed from the drivers.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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mdiobus_alloc() might return NULL, but its return value is not
checked in mdio_mux_init(). This could potentially lead to a NULL
pointer dereference. Fix it by checking the return value
Fixes: 0ca2997d1452 ("netdev/of/phy: Add MDIO bus multiplexer support.")
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
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for_each_available_child_of_node performs an of_node_get on each iteration, so
a break out of the loop requires an of_node_put.
A simplified version of the semantic patch that fixes this problem is as
follows (http://coccinelle.lip6.fr):
// <smpl>
@@
local idexpression r.n;
expression r,e;
@@
for_each_available_child_of_node(r,n) {
...
(
of_node_put(n);
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e = n
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+ of_node_put(n);
? break;
)
...
}
... when != n
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
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of_mdio_find_bus() leaks a struct device refcount, caused by using
class_find_device() and not realising that the device reference has
its refcount incremented:
* Note, you will need to drop the reference with put_device() after use.
...
while ((dev = class_dev_iter_next(&iter))) {
if (match(dev, data)) {
get_device(dev);
break;
}
Update the comment, and arrange for the phy code to drop this refcount
when disposing of a reference to it.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
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The mdio-mux driver scans all child mdio nodes, without regard to whether
the node is actually used. Some device trees include all possible
mdio-mux nodes and rely on the boot loader to disable those that are not
present, based on some run-time configuration. Those nodes need to be
skipped.
Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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With lockdep enabled we get:
=============================================
[ INFO: possible recursive locking detected ]
3.4.4-Cavium-Octeon+ #313 Not tainted
---------------------------------------------
kworker/u:1/36 is trying to acquire lock:
(&bus->mdio_lock){+.+...}, at: [<ffffffff813da7e8>] mdio_mux_read+0x38/0xa0
but task is already holding lock:
(&bus->mdio_lock){+.+...}, at: [<ffffffff813d79e4>] mdiobus_read+0x44/0x88
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&bus->mdio_lock);
lock(&bus->mdio_lock);
*** DEADLOCK ***
May be due to missing lock nesting notation
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.
.
This is a false positive, since we are indeed using 'nested' locking,
we need to use mutex_lock_nested().
Now in theory we can stack multiple MDIO multiplexers, but that would
require passing the nesting level (which is difficult to know) to
mutex_lock_nested(). Instead we assume the simple case of a single
level of nesting. Since these are only warning messages, it isn't so
important to solve the general case.
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This patch adds a somewhat generic framework for MDIO bus
multiplexers. It is modeled on the I2C multiplexer.
The multiplexer is needed if there are multiple PHYs with the same
address connected to the same MDIO bus adepter, or if there is
insufficient electrical drive capability for all the connected PHY
devices.
Conceptually it could look something like this:
------------------
| Control Signal |
--------+---------
|
--------------- --------+------
| MDIO MASTER |---| Multiplexer |
--------------- --+-------+----
| |
C C
h h
i i
l l
d d
| |
--------- A B ---------
| | | | | |
| PHY@1 +-------+ +---+ PHY@1 |
| | | | | |
--------- | | ---------
--------- | | ---------
| | | | | |
| PHY@2 +-------+ +---+ PHY@2 |
| | | |
--------- ---------
This framework configures the bus topology from device tree data. The
mechanics of switching the multiplexer is left to device specific
drivers.
The follow-on patch contains a multiplexer driven by GPIO lines.
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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