linux-kernel - Re: [PATCH v6 03/10] usb: dwc3: omap: Pass VBUS and ID events transparently

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Message-ID: <87egacnxtr.fsf@intel.com>
Date:	Mon, 11 Apr 2016 15:18:08 +0300
From:	Felipe Balbi <balbi@...nel.org>
To:	Roger Quadros <rogerq@...com>
Cc:	tony@...mide.com, Joao.Pinto@...opsys.com,
	sergei.shtylyov@...entembedded.com, peter.chen@...escale.com,
	jun.li@...escale.com, grygorii.strashko@...com,
	yoshihiro.shimoda.uh@...esas.com, nsekhar@...com,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org, Roger Quadros <rogerq@...com>
Subject: Re: [PATCH v6 03/10] usb: dwc3: omap: Pass VBUS and ID events transparently


Hi,

Roger Quadros <rogerq@...com> writes:
> Don't make any decisions regarding VBUS session based on ID
> status. That is best left to the OTG core.

what about builds who don't want OTG and/or dual-role ?

> Pass ID and VBUS events independent of each other so that OTG
> core knows exactly what to do.
>
> This makes dual-role with extcon work with OTG irq on OMAP platforms.
>
> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
>  drivers/usb/dwc3/dwc3-omap.c | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/usb/dwc3/dwc3-omap.c b/drivers/usb/dwc3/dwc3-omap.c
> index 51ca098..c9b918d 100644
> --- a/drivers/usb/dwc3/dwc3-omap.c
> +++ b/drivers/usb/dwc3/dwc3-omap.c
> @@ -233,19 +233,14 @@ static void dwc3_omap_set_mailbox(struct dwc3_omap *omap,
>  		}
>  
>  		val = dwc3_omap_read_utmi_ctrl(omap);
> -		val &= ~(USBOTGSS_UTMI_OTG_CTRL_IDDIG
> -				| USBOTGSS_UTMI_OTG_CTRL_VBUSVALID
> -				| USBOTGSS_UTMI_OTG_CTRL_SESSEND);
> -		val |= USBOTGSS_UTMI_OTG_CTRL_SESSVALID
> -				| USBOTGSS_UTMI_OTG_CTRL_POWERPRESENT;
> +		val &= ~USBOTGSS_UTMI_OTG_CTRL_IDDIG;

this creates the possibility of having a USB peripheral with VBUS_VALID,
right 

>  		dwc3_omap_write_utmi_ctrl(omap, val);
>  		break;
>  
>  	case OMAP_DWC3_VBUS_VALID:
>  		val = dwc3_omap_read_utmi_ctrl(omap);
>  		val &= ~USBOTGSS_UTMI_OTG_CTRL_SESSEND;
> -		val |= USBOTGSS_UTMI_OTG_CTRL_IDDIG
> -				| USBOTGSS_UTMI_OTG_CTRL_VBUSVALID
> +		val |= USBOTGSS_UTMI_OTG_CTRL_VBUSVALID
>  				| USBOTGSS_UTMI_OTG_CTRL_SESSVALID
>  				| USBOTGSS_UTMI_OTG_CTRL_POWERPRESENT;

I remember discussing this with TI's IP owner back in OMAP5 days. This
code was a result of talking to that guy and was, back then, tested by
Silicon Validation team. I would strongly advise that before changing
these bits you check with whoever's currently handling this IP inside TI
to make sure your changes are still within the expectations of the
wrapper block.

-- 
balbi

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