linux-kernel - Re: [PATCH v2 3/9] mfd: wm5102: Ensure we always boot the device fully

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Message-ID: <20150429122532.GF9169@x1>
Date:	Wed, 29 Apr 2015 13:25:32 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
Cc:	broonie@...nel.org, sameo@...ux.intel.com,
	linux-kernel@...r.kernel.org, lgirdwood@...il.com,
	patches@...nsource.wolfsonmicro.com
Subject: Re: [PATCH v2 3/9] mfd: wm5102: Ensure we always boot the device
 fully

On Fri, 17 Apr 2015, Charles Keepax wrote:

> The wm5102 uses a custom boot sequence and the standard boot sequence is
> disabled. However, the standard boot sequence must be run at least once
> after a cold boot (caused by either a hard reset or removal of AVDD).
> Unfortunately the register WRITE_SEQUENCER_CTRL_3 is not affected by the
> hardware reset. This means if the device has been previously booted but
> the AVDD supply has never been removed, arizona_dev_init will reset the
> chip but the boot sequence will not run, which can cause numerous
> problems. The solution is to manually clear this register and then boot
> the chip again, which is what this patch does.
> 
> Signed-off-by: Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
> ---
>  drivers/mfd/arizona-core.c |   50 +++++++++++++++++++++++++++++++++++--------
>  1 files changed, 40 insertions(+), 10 deletions(-)

Hacks galore!

Acked-by: Lee Jones <lee.jones@...aro.org>

> diff --git a/drivers/mfd/arizona-core.c b/drivers/mfd/arizona-core.c
> index c0e8a96..73418bd 100644
> --- a/drivers/mfd/arizona-core.c
> +++ b/drivers/mfd/arizona-core.c
> @@ -344,6 +344,33 @@ err_fll:
>  		return err;
>  }
>  
> +static int wm5102_clear_write_sequencer(struct arizona *arizona)
> +{
> +	int ret;
> +
> +	ret = regmap_write(arizona->regmap, ARIZONA_WRITE_SEQUENCER_CTRL_3,
> +			   0x0);
> +	if (ret) {
> +		dev_err(arizona->dev,
> +			"Failed to clear write sequencer state: %d\n", ret);
> +		return ret;
> +	}
> +
> +	arizona_enable_reset(arizona);
> +	regulator_disable(arizona->dcvdd);
> +
> +	msleep(20);
> +
> +	ret = regulator_enable(arizona->dcvdd);
> +	if (ret) {
> +		dev_err(arizona->dev, "Failed to re-enable DCVDD: %d\n", ret);
> +		return ret;
> +	}
> +	arizona_disable_reset(arizona);
> +
> +	return 0;
> +}
> +
>  #ifdef CONFIG_PM
>  static int arizona_runtime_resume(struct device *dev)
>  {
> @@ -810,21 +837,24 @@ int arizona_dev_init(struct arizona *arizona)
>  	case WM5102:
>  		ret = regmap_read(arizona->regmap,
>  				  ARIZONA_WRITE_SEQUENCER_CTRL_3, &val);
> -		if (ret != 0)
> +		if (ret) {
>  			dev_err(dev,
>  				"Failed to check write sequencer state: %d\n",
>  				ret);
> -		else if (val & 0x01)
> -			break;
> -		/* Fall through */
> -	default:
> -		ret = arizona_wait_for_boot(arizona);
> -		if (ret != 0) {
> -			dev_err(arizona->dev,
> -				"Device failed initial boot: %d\n", ret);
> -			goto err_reset;
> +		} else if (val & 0x01) {
> +			ret = wm5102_clear_write_sequencer(arizona);
> +			if (ret)
> +				return ret;
>  		}
>  		break;
> +	default:
> +		break;
> +	}
> +
> +	ret = arizona_wait_for_boot(arizona);
> +	if (ret) {
> +		dev_err(arizona->dev, "Device failed initial boot: %d\n", ret);
> +		goto err_reset;
>  	}
>  
>  	/* Read the device ID information & do device specific stuff */

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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