On Tuesday 04 February 2014 11:03 PM, Andrew Lunn wrote:
> 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@xxxxxxx>
> Tested-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx>
Acked-by: Kishon Vijay Abraham I <kishon@xxxxxx>
> ---
> v2
> No change.
> v4
> combine !phy and IS_ERR().
> Add Tested-by
> ---
> Documentation/phy.txt | 6 ++++++
> drivers/phy/phy-core.c | 17 ++++++++++++++++-
> 2 files changed, 22 insertions(+), 1 deletion(-)
>
> 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
> diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
> index 645c867c1257..a9cdeee20d91 100644
> --- a/drivers/phy/phy-core.c
> +++ b/drivers/phy/phy-core.c
> @@ -162,6 +162,9 @@ int phy_init(struct phy *phy)
> {
> int ret;
>
> + if (!phy)
> + return 0;
> +
> ret = phy_pm_runtime_get_sync(phy);
> if (ret < 0 && ret != -ENOTSUPP)
> return ret;
> @@ -187,6 +190,9 @@ int phy_exit(struct phy *phy)
> {
> int ret;
>
> + if (!phy)
> + return 0;
> +
> ret = phy_pm_runtime_get_sync(phy);
> if (ret < 0 && ret != -ENOTSUPP)
> return ret;
> @@ -212,6 +218,9 @@ int phy_power_on(struct phy *phy)
> {
> int ret;
>
> + if (!phy)
> + return 0;
> +
> ret = phy_pm_runtime_get_sync(phy);
> if (ret < 0 && ret != -ENOTSUPP)
> return ret;
> @@ -240,6 +249,9 @@ int phy_power_off(struct phy *phy)
> {
> int ret;
>
> + if (!phy)
> + return 0;
> +
> mutex_lock(&phy->mutex);
> if (phy->power_count == 1 && phy->ops->power_off) {
> ret = phy->ops->power_off(phy);
> @@ -308,7 +320,7 @@ err0:
> */
> void phy_put(struct phy *phy)
> {
> - if (IS_ERR(phy))
> + if (!phy || IS_ERR(phy))
> return;
>
> module_put(phy->ops->owner);
> @@ -328,6 +340,9 @@ void devm_phy_put(struct device *dev, struct phy *phy)
> {
> int r;
>
> + if (!phy)
> + return;
> +
> r = devres_destroy(dev, devm_phy_release, devm_phy_match, phy);
> dev_WARN_ONCE(dev, r, "couldn't find PHY resource\n");
> }
>
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