Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH] usb: cdns3: gadget: Don't manage pullups
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>
References: <20191023090232.27237-1-rogerq@ti.com>
 <BYAPR07MB4709A6212601A75DCB1A25ACDD6B0@BYAPR07MB4709.namprd07.prod.outlook.com>
 <20191025031343.GA13392@b29397-desktop>
From:   Roger Quadros <rogerq@ti.com>
Message-ID: <83a1da01-19d6-65a9-aecd-2027fd62a272@ti.com>
Date:   Fri, 25 Oct 2019 12:59:17 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.9.0
MIME-Version: 1.0
In-Reply-To: <20191025031343.GA13392@b29397-desktop>
Content-Type: text/plain; charset="utf-8"; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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