On 03/22/2011 03:31 PM, Mark Brown wrote:
> No need to hold the child lock, when we take the reference on the supply
> we own the reference. It's just that the systems which need to use
> daisychained regulators (mostly a DCDC to power LDOs for better
> efficiency) are moderately rare and tend to not bother representing the
> supply relationship as the parent regulator tends to be always on.
>
> In fact it looks rather like the refcounting for supplies is wrong
> anyway, regulator_disable() unconditionally drops references to supplies
> but regulator_enable() only enables them if the refcount was previously
> zero, and it appears we don't clean up supplies after failed enables.
> The below patch (which I've not even compile tested) should resolve both
> issues, could you give it a spin and let me know if it works for you
> please?
>
> diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
> index 3ffc697..0a7fbde 100644
> --- a/drivers/regulator/core.c
> +++ b/drivers/regulator/core.c
> @@ -1284,19 +1284,6 @@ static int _regulator_enable(struct regulator_dev *rdev)
> {
> int ret, delay;
>
> - if (rdev->use_count == 0) {
> - /* do we need to enable the supply regulator first */
> - if (rdev->supply) {
> - mutex_lock(&rdev->supply->mutex);
> - ret = _regulator_enable(rdev->supply);
> - mutex_unlock(&rdev->supply->mutex);
> - if (ret < 0) {
> - rdev_err(rdev, "failed to enable: %d\n", ret);
> - return ret;
> - }
> - }
> - }
> -
> /* check voltage and requested load before enabling */
> if (rdev->constraints &&
> (rdev->constraints->valid_ops_mask & REGULATOR_CHANGE_DRMS))
> @@ -1370,10 +1357,27 @@ int regulator_enable(struct regulator *regulator)
> {
> struct regulator_dev *rdev = regulator->rdev;
> int ret = 0;
> + int disret;
> +
> + if (rdev->supply) {
> + ret = regulator_enable(rdev->supply);
This should be _regulator_enable instead of regulator_enable. There will
also need to be a mutex lock and unlock around it for rdev->supply->mutex.
I think that it needs to iterate through all supplies in the chain
similar to how it is done in regulator_disable.
> + if (ret < 0) {
> + rdev_err(rdev, "failed to enable supply: %d\n", ret);
> + return ret;
> + }
> + }
>
> mutex_lock(&rdev->mutex);
> ret = _regulator_enable(rdev);
> mutex_unlock(&rdev->mutex);
> +
> + if (ret != 0 && rdev->supply) {
> + disret = regulator_disable(rdev->supply);
This should be _regulator_disable instead of regulator_disable. There
will also need to be a mutex lock and unlock around it for
rdev->supply->mutex. Additionally, a while loop is needed to disable all
supplies in the chain (same as in regulator_disable).
> + if (disret < 0)
> + rdev_err(rdev, "failed to disable supply: %d\n",
> + disret);
> + }
> +
> return ret;
> }
> EXPORT_SYMBOL_GPL(regulator_enable);
This patch doesn't compile. A few changes are needed.
Thanks,
David
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