linux-kernel - Re: [PATCH 2/3] extcon: intel-cht-wc: Disable external 5v boost converter on probe

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Date:   Tue, 04 Apr 2017 15:31:40 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Hans de Goede <hdegoede@...hat.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>
Cc:     Takashi Iwai <tiwai@...e.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] extcon: intel-cht-wc: Disable external 5v boost
 converter on probe

Hi,

On 2017년 04월 03일 20:26, Hans de Goede wrote:
> Disable the 5v boost converter on probe in case it was left on by
> the BIOS, this fixes 2 problems:
> 
> 1) This gets seen by the external battery charger as a valid Vbus
>    supply and it then tries to feed Vsys from this creating a
>    feedback loop which causes aprox. 300 mA extra battery drain
>    (and unless we drive the external-charger-disable pin high it
>    also tries to charge the battery causing even more feedback).
> 2) This gets seen by the pwrsrc block as a SDP USB Vbus supply
> 
> Since the external battery charger has its own 5v boost converter
> which does not have these issues, we simply turn the separate
> external 5v boost converter off and leave it off entirely.
> 
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> ---
>  drivers/extcon/extcon-intel-cht-wc.c | 38 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
> 
> diff --git a/drivers/extcon/extcon-intel-cht-wc.c b/drivers/extcon/extcon-intel-cht-wc.c
> index f1c43af..8651f63 100644
> --- a/drivers/extcon/extcon-intel-cht-wc.c
> +++ b/drivers/extcon/extcon-intel-cht-wc.c
> @@ -64,6 +64,11 @@
>  #define CHT_WC_PWRSRC_ID_GND		BIT(3)
>  #define CHT_WC_PWRSRC_ID_FLOAT		BIT(4)
>  
> +#define CHT_WC_GPIO0_CTLO		0x6e2b
> +#define CHT_WC_GPIO_CTLO_OUTPUT		BIT(0)

CHT_WC_GPIO0_CTLO or CHT_WC_GPIO_CTLO ?
Because  CHT_WC_GPIO_CTLO_OUTPUT defintion use just 'GPIO' instead of 'GPIO0'.

I prefer to change the definition name as following with '_MASK' postfix.
- CHT_WC_GPIO_CTLO_OUTPUT -> CHT_WC_GPIO_CTLO_OUTPUT_MASK


> +#define CHT_WC_GPIO0_CTLO		0x6e2b
> +
> +#define CHT_WC_VBUS_ENABLE_GPIO		2

I think that 'CHT_WC_GPIO0_CTLO + CHT_WC_VBUS_ENABLE_GPIO' is a separate
register address. Maybe you can define the separate register offset
instead of the separate the CHT_WC_VBUS_ENABLE_GPIO offset.

> +
>  enum cht_wc_usb_id {
>  	USB_ID_OTG,
>  	USB_ID_GND,
> @@ -170,6 +175,24 @@ static void cht_wc_extcon_set_phymux(struct cht_wc_extcon_data *ext, u8 state)
>  		dev_err(ext->dev, "Error writing phyctrl: %d\n", ret);
>  }
>  
> +static void cht_wc_extcon_set_5v_boost(struct cht_wc_extcon_data *ext,
> +				       bool enable)
> +{
> +	int ret, val;
> +
> +	val = enable ? CHT_WC_GPIO_CTLO_OUTPUT : 0;
> +
> +	/*
> +	 * The 5V boost converter is enabled through a gpio on the PMIC, since
> +	 * there currently is no gpio driver we access the gpio reg directly.
> +	 */
> +	ret = regmap_update_bits(ext->regmap,
> +				 CHT_WC_GPIO0_CTLO + CHT_WC_VBUS_ENABLE_GPIO,
> +				 CHT_WC_GPIO_CTLO_OUTPUT, val);
> +	if (ret)
> +		dev_err(ext->dev, "Error writing Vbus GPIO CTLO: %d\n", ret);
> +}
> +
>  /* Small helper to sync EXTCON_CHG_USB_SDP and EXTCON_USB state */
>  static void cht_wc_extcon_set_state(struct cht_wc_extcon_data *ext,
>  				    unsigned int cable, bool state)
> @@ -280,6 +303,21 @@ static int cht_wc_extcon_probe(struct platform_device *pdev)
>  	if (IS_ERR(ext->edev))
>  		return PTR_ERR(ext->edev);
>  
> +	/*
> +	 * When a host-cable is detected the BIOS enables an external 5v boost
> +	 * converter to power connected devices there are 2 problems with this:
> +	 * 1) This gets seen by the external battery charger as a valid Vbus
> +	 *    supply and it then tries to feed Vsys from this creating a
> +	 *    feedback loop which causes aprox. 300 mA extra battery drain
> +	 *    (and unless we drive the external-charger-disable pin high it
> +	 *    also tries to charge the battery causing even more feedback).
> +	 * 2) This gets seen by the pwrsrc block as a SDP USB Vbus supply
> +	 * Since the external battery charger has its own 5v boost converter
> +	 * which does not have these issues, we simply turn the separate
> +	 * external 5v boost converter off and leave it off entirely.
> +	 */
> +	cht_wc_extcon_set_5v_boost(ext, false);
> +
>  	/* Enable sw control */
>  	ret = cht_wc_extcon_sw_control(ext, true);
>  	if (ret)
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics