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Date:   Tue, 4 Apr 2017 12:52:32 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Chanwoo Choi <cw00.choi@...sung.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 04-04-17 08:31, Chanwoo Choi wrote:
> 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.

All the other BIT definitions don't use _MASK either so
that would be inconsistent.

> - 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.

Ok, I will send you a version 2 using:

#define CHT_WC_VBUS_GPIO_CTLO			0x6e2d
#define CHT_WC_VBUS_GPIO_CTLO_OUTPUT		BIT(0)

Regards,

Hans



>
>> +
>>  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)
>>
>
>

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