linux-kernel - Re: [PATCH 3/6] twl4030_charger: allow charging whenever VBUS is present.

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Date:	Wed, 25 Apr 2012 14:33:25 +0300
From:	Grazvydas Ignotas <notasas@...il.com>
To:	NeilBrown <neilb@...e.de>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>, Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-omap@...r.kernel.org
Subject: Re: [PATCH 3/6] twl4030_charger: allow charging whenever VBUS is present.

On Wed, Apr 25, 2012 at 10:33 AM, NeilBrown <neilb@...e.de> wrote:
> We currently refuse to charge if the USB ID pin is grounded, even
> though VBUS might be present.
> However some chargers do pull the ID pin low through a resistor which
> might be as low as 47Kohm (openmoko charger).
>
> The documentation is unclear but some experimental evidence suggests
> that when the charge pump provides VBUS that doesn't get reflected in
> HW_CONDITIONS, so we should be safe to ignore the ID pin.

On pandora I see the opposite, STS_VBUS is set regardless of who
drives it, so this will break pandora..

>
> Signed-off-by: NeilBrown <neilb@...e.de>
> ---
>
>  drivers/power/twl4030_charger.c |    6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/drivers/power/twl4030_charger.c b/drivers/power/twl4030_charger.c
> index 0511610..684662a 100644
> --- a/drivers/power/twl4030_charger.c
> +++ b/drivers/power/twl4030_charger.c
> @@ -155,11 +155,7 @@ static int twl4030_bci_have_vbus(struct twl4030_bci *bci)
>
>        dev_dbg(bci->dev, "check_vbus: HW_CONDITIONS %02x\n", hwsts);
>
> -       /* in case we also have STS_USB_ID, VBUS is driven by TWL itself */
> -       if ((hwsts & TWL4030_STS_VBUS) && !(hwsts & TWL4030_STS_USB_ID))
> -               return 1;
> -
> -       return 0;
> +       return (hwsts & TWL4030_STS_VBUS);
>  }
>
>  /*
>
>


-- 
Gražvydas
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