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SubjectRe: [PATCH] regulator: When constraining modes fall back to higher power modes
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On Wed, 2011-03-30 at 06:29 +0900, Mark Brown wrote:
> If a mode requested by a consumer is not allowed by constraints
> automatically fall back to a higher power mode if possible. This
> ensures that consumers get at least the output they requested while
> allowing machine drivers to transparently limit lower power modes
> if required.
>
> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
> ---
>
> I've not actually had a chance to test this but throwing it out there
> for comment and testing now; someone with an OMAP board can probably
> test fairly quickly as the OMAP HSMMC driver is using set_mode().
>
> drivers/regulator/core.c | 24 +++++++++++++++---------
> 1 files changed, 15 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
> index 3ffc697..a634946 100644
> --- a/drivers/regulator/core.c
> +++ b/drivers/regulator/core.c
> @@ -197,9 +197,9 @@ static int regulator_check_current_limit(struct regulator_dev *rdev,
> }
>
> /* operating mode constraint check */
> -static int regulator_check_mode(struct regulator_dev *rdev, int mode)
> +static int regulator_mode_constrain(struct regulator_dev *rdev, int *mode)
> {
> - switch (mode) {
> + switch (*mode) {
> case REGULATOR_MODE_FAST:
> case REGULATOR_MODE_NORMAL:
> case REGULATOR_MODE_IDLE:
> @@ -217,11 +217,17 @@ static int regulator_check_mode(struct regulator_dev *rdev, int mode)
> rdev_err(rdev, "operation not allowed\n");
> return -EPERM;
> }
> - if (!(rdev->constraints->valid_modes_mask & mode)) {
> - rdev_err(rdev, "invalid mode %x\n", mode);
> - return -EINVAL;
> +
> + /* The modes are bitmasks, the most power hungry modes having
> + * the lowest values. If the requested mode isn't supported
> + * try higher modes. */
> + while (*mode) {
> + if (rdev->constraints->valid_modes_mask & *mode)
> + return 0;
> + *mode /= 2;
> }
> - return 0;
> +
> + return -EINVAL;
> }

It's late and I'm wondering if it's cleaner here just to :-

if (mask & *mode)
return 0;
*mode = fls(mask);
if (*mode)
return 0;
return -EINVAL;


What do you think ?

Liam



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