linux-kernel - Re: [PATCH 3/3] mfd: arizona: Use regmap_read_poll

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Date:   Thu, 5 Jan 2017 08:07:01 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
Cc:     patches@...nsource.wolfsonmicro.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] mfd: arizona: Use regmap_read_poll_timeout instead
 of hard coding it

On Wed, 04 Jan 2017, Charles Keepax wrote:

> arizona_poll_reg essentially hard-codes regmap_read_poll_timeout, this
> patch updates the implementation to use regmap_read_poll_timeout. We
> still keep arizona_poll_reg around as regmap_read_poll_timeout is a
> macro so rather than expand this for each caller keep it wrapped in
> arizona_poll_reg.
> 
> Signed-off-by: Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
> ---
>  drivers/mfd/arizona-core.c | 28 +++++++++++-----------------
>  1 file changed, 11 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/mfd/arizona-core.c b/drivers/mfd/arizona-core.c
> index 4cb34c3..e6fae3c 100644
> --- a/drivers/mfd/arizona-core.c
> +++ b/drivers/mfd/arizona-core.c
> @@ -236,28 +236,22 @@ static irqreturn_t arizona_overclocked(int irq, void *data)
>  }
>  
>  static int arizona_poll_reg(struct arizona *arizona,
> -			    int timeout, unsigned int reg,
> +			    int npolls, unsigned int reg,
>  			    unsigned int mask, unsigned int target)
>  {
> +	const int poll_us = 7500;

Get rid of this and replace its usage with a nice #define describing
exactly what the timeout is for i.e what timed out.

... okay, I just read the doc.  This should really be 'SLEEP'.

Where did 7500 come from anyway?  Is it documented?

>  	unsigned int val = 0;
> -	int ret, i;
> -
> -	for (i = 0; i < timeout; i++) {
> -		ret = regmap_read(arizona->regmap, reg, &val);
> -		if (ret != 0) {
> -			dev_err(arizona->dev, "Failed to read reg 0x%x: %d\n",
> -				reg, ret);
> -			continue;
> -		}
> -
> -		if ((val & mask) == target)
> -			return 0;
> +	int ret;
>  
> -		usleep_range(1000, 5000);
> -	}
> +	ret = regmap_read_poll_timeout(arizona->regmap,
> +				       ARIZONA_INTERRUPT_RAW_STATUS_5, val,
> +				       ((val & mask) == target), poll_us,
> +				       npolls * poll_us);

What's the relevance of npolls?  Is this number documented, or was it
pulled from your ... err, the air?

> +	if (ret)
> +		dev_err(arizona->dev, "Polling reg 0x%x timed out: %x\n",
> +			reg, val);
>  
> -	dev_err(arizona->dev, "Polling reg 0x%x timed out: %x\n", reg, val);
> -	return -ETIMEDOUT;
> +	return ret;
>  }
>  
>  static int arizona_wait_for_boot(struct arizona *arizona)

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