Re: [PATCH] usb: cdns3: gadget: Don't manage pullups

From: Roger Quadros <rogerq@ti.com>
To: Peter Chen <peter.chen@nxp.com>, Pawel Laszczak <pawell@cadence.com>
Cc: "felipe.balbi@linux.intel.com" <felipe.balbi@linux.intel.com>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"nsekhar@ti.com" <nsekhar@ti.com>,
	Rahul Kumar <kurahul@cadence.com>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] usb: cdns3: gadget: Don't manage pullups
Date: Fri, 25 Oct 2019 12:59:17 +0300	[thread overview]
Message-ID: <83a1da01-19d6-65a9-aecd-2027fd62a272@ti.com> (raw)
In-Reply-To: <20191025031343.GA13392@b29397-desktop>

Peter,

On 25/10/2019 06:13, Peter Chen wrote:
> On 19-10-23 09:17:45, Pawel Laszczak wrote:
>> Hi,
>>
>> Reviewed-by: Pawel Laszczak <pawell@cadence.com>
> 
> Hi Roger & Pawel,
> 
> Assume gadget function has already enabled, if you switch host mode
> to device mode, with your changes, where the device mode will be enabled
> again?

When it switches from device mode to host the UDC is removed. When we switch
back from host to device mode the UDC is added, so,

usb_add_gadget_udc_release()-> check_pending_gadget_drivers()->
udc_bind_to_driver()->usb_udc_connect_control()->usb_gadget_connect()->
gadget->ops->pullup()

cheers,
-roger
> 
> Peter
>>
>> Regards,
>> Pawel,
>>
>>> The USB gadget core is supposed to manage pullups
>>> of the controller. Don't manage pullups from within
>>> the controller driver. Otherwise, function drivers
>>> are not able to keep the controller disconnected from
>>> the bus till they are ready. (e.g. g_webcam)
>>>
>>> Signed-off-by: Roger Quadros <rogerq@ti.com>
>>> ---
>>> Hi Greg/Felipe,
>>>
>>> This can be used for -rc as it is a bug fix.
>>>
>>> cheers,
>>> -roger
>>>
>>> drivers/usb/cdns3/gadget.c | 4 ----
>>> 1 file changed, 4 deletions(-)
>>>
>>> diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
>>> index 2ca280f4c054..714382d96055 100644
>>> --- a/drivers/usb/cdns3/gadget.c
>>> +++ b/drivers/usb/cdns3/gadget.c
>>> @@ -2324,8 +2324,6 @@ static void cdns3_gadget_config(struct cdns3_device *priv_dev)
>>> 	writel(USB_CONF_CLK2OFFDS | USB_CONF_L1DS, &regs->usb_conf);
>>>
>>> 	cdns3_configure_dmult(priv_dev, NULL);
>>> -
>>> -	cdns3_gadget_pullup(&priv_dev->gadget, 1);
>>> }
>>>
>>> /**
>>> @@ -2708,8 +2706,6 @@ static int cdns3_gadget_suspend(struct cdns3 *cdns, bool do_wakeup)
>>> 	/* disable interrupt for device */
>>> 	writel(0, &priv_dev->regs->usb_ien);
>>>
>>> -	cdns3_gadget_pullup(&priv_dev->gadget, 0);
>>> -
>>> 	return 0;
>>> }
>>>
>>> --
>>> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
>>> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
>>
> 

-- 
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki