Re: [PATCH RESEND 3/4] mfd: arizona: Update arizona_poll_reg to take a timeout in milliseconds

From: Lee Jones
Date: Wed Feb 08 2017 - 05:38:52 EST


On Tue, 31 Jan 2017, Charles Keepax wrote:

> Currently, we specify the timeout in terms of the number of polls but it
> is more clear from a user of the functions perspective to specify the
> timeout directly in milliseconds, as such update the function to these new
> semantics.
>
> Signed-off-by: Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/mfd/arizona-core.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/mfd/arizona-core.c b/drivers/mfd/arizona-core.c
> index 4cb34c3..ae4cdc4 100644
> --- a/drivers/mfd/arizona-core.c
> +++ b/drivers/mfd/arizona-core.c
> @@ -235,14 +235,18 @@ static irqreturn_t arizona_overclocked(int irq, void *data)
> return IRQ_HANDLED;
> }
>
> +#define ARIZONA_REG_POLL_DELAY_MS 5
> +
> static int arizona_poll_reg(struct arizona *arizona,
> - int timeout, unsigned int reg,
> + int timeout_ms, unsigned int reg,
> unsigned int mask, unsigned int target)
> {
> + unsigned int npolls = (timeout_ms + ARIZONA_REG_POLL_DELAY_MS - 1) /
> + ARIZONA_REG_POLL_DELAY_MS;

Why the over-complication?

Shouldn't this just be "timeout_ms / ARIZONA_REG_POLL_DELAY_MS"?

> unsigned int val = 0;
> int ret, i;
>
> - for (i = 0; i < timeout; i++) {
> + for (i = 0; i < npolls; i++) {
> ret = regmap_read(arizona->regmap, reg, &val);
> if (ret != 0) {
> dev_err(arizona->dev, "Failed to read reg 0x%x: %d\n",
> @@ -253,7 +257,8 @@ static int arizona_poll_reg(struct arizona *arizona,
> if ((val & mask) == target)
> return 0;
>
> - usleep_range(1000, 5000);
> + usleep_range((ARIZONA_REG_POLL_DELAY_MS * 1000) / 2,
> + ARIZONA_REG_POLL_DELAY_MS * 1000);

I'm sure there is a macro for conversion from ms to us.

By using such a wide range, you are now not honouring the timeout set
by the caller by as much as 50%.

> }
>
> dev_err(arizona->dev, "Polling reg 0x%x timed out: %x\n", reg, val);
> @@ -269,7 +274,7 @@ static int arizona_wait_for_boot(struct arizona *arizona)
> * we won't race with the interrupt handler as it'll be blocked on
> * runtime resume.
> */
> - ret = arizona_poll_reg(arizona, 5, ARIZONA_INTERRUPT_RAW_STATUS_5,
> + ret = arizona_poll_reg(arizona, 25, ARIZONA_INTERRUPT_RAW_STATUS_5,
> ARIZONA_BOOT_DONE_STS, ARIZONA_BOOT_DONE_STS);
>
> if (!ret)
> @@ -339,7 +344,7 @@ static int arizona_enable_freerun_sysclk(struct arizona *arizona,
> ret);
> return ret;
> }
> - ret = arizona_poll_reg(arizona, 25, ARIZONA_INTERRUPT_RAW_STATUS_5,
> + ret = arizona_poll_reg(arizona, 125, ARIZONA_INTERRUPT_RAW_STATUS_5,
> ARIZONA_FLL1_CLOCK_OK_STS,
> ARIZONA_FLL1_CLOCK_OK_STS);
> if (ret)
> @@ -403,7 +408,7 @@ static int wm5102_apply_hardware_patch(struct arizona *arizona)
> goto err;
> }
>
> - ret = arizona_poll_reg(arizona, 5, ARIZONA_WRITE_SEQUENCER_CTRL_1,
> + ret = arizona_poll_reg(arizona, 25, ARIZONA_WRITE_SEQUENCER_CTRL_1,
> ARIZONA_WSEQ_BUSY, 0);
> if (ret)
> regmap_write(arizona->regmap, ARIZONA_WRITE_SEQUENCER_CTRL_0,

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org â Open source software for ARM SoCs
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