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authorAndrew Lunn <andrew@lunn.ch>2014-02-04 18:33:11 +0100
committerJason Cooper <jason@lakedaemon.net>2014-02-05 05:27:54 +0000
commit04c2facad8fee66c981a51852806d8923336f362 (patch)
tree89bda05db2d208a151ed216bc4099d3371c7e6a2 /Documentation/phy.txt
parent38dbfb59d1175ef458d006556061adeaa8751b72 (diff)
downloadkernel-04c2facad8fee66c981a51852806d8923336f362.tar.gz
drivers: phy: Make NULL a valid phy reference
The common clock framework considers NULL a valid clock reference. This makes handling optional clocks simple, in that if the optional clock is not available, a NULL reference can be used in the place of a real clock, simplifying the clock consumer. Extend this concept to the phy consumer API. A NULL can be passed to the release calls, the phy_init() and phy_exit() calls, and phy_power_on() and phy_power_off() and a NOP is performed. Signed-off-by: Andrew Lunn <andrew@lunn.ch> Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> Acked-by: Kishon Vijay Abraham I <kishon@ti.com> Signed-off-by: Jason Cooper <jason@lakedaemon.net>
Diffstat (limited to 'Documentation/phy.txt')
-rw-r--r--Documentation/phy.txt6
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/phy.txt b/Documentation/phy.txt
index 0103e4b15b0e..2e24b993e95f 100644
--- a/Documentation/phy.txt
+++ b/Documentation/phy.txt
@@ -84,6 +84,12 @@ The only difference between the two APIs is that devm_phy_get associates the
device with the PHY using devres on successful PHY get. On driver detach,
release function is invoked on the the devres data and devres data is freed.
+It should be noted that NULL is a valid phy reference. All phy
+consumer calls on the NULL phy become NOPs. That is the release calls,
+the phy_init() and phy_exit() calls, and phy_power_on() and
+phy_power_off() calls are all NOP when applied to a NULL phy. The NULL
+phy is useful in devices for handling optional phy devices.
+
5. Releasing a reference to the PHY
When the controller no longer needs the PHY, it has to release the reference