linux-kernel - Re: [RFC PATCH v2 05/15] usb:cdns3: Added DRD support

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Date:   Tue, 27 Nov 2018 14:10:36 +0200
From:   Roger Quadros <rogerq@...com>
To:     Pawel Laszczak <pawell@...ence.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
CC:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Alan Douglas <adouglas@...ence.com>,
        "jbergsagel@...com" <jbergsagel@...com>,
        "nsekhar@...com" <nsekhar@...com>, "nm@...com" <nm@...com>,
        Suresh Punnoose <sureshp@...ence.com>,
        "peter.chen@....com" <peter.chen@....com>,
        Pawel Jez <pjez@...ence.com>, Rahul Kumar <kurahul@...ence.com>
Subject: Re: [RFC PATCH v2 05/15] usb:cdns3: Added DRD support

Pawel,

On 27/11/18 13:29, Pawel Laszczak wrote:
> Hi Roger
> 
>>>> Patch adds supports for detecting Host/Device mode.
>>>> +
>>>> +static int cdns3_otg_get_id(struct cdns3 *cdns)
>>>> +{
>>>> +	int id;
>>>> +
>>>> +	id = readl(&cdns->otg_regs->sts) & OTGSTS_ID_VALUE;
>>>> +	dev_dbg(cdns->dev, "OTG ID: %d", id);
>>>> +	return id;
>>>> +}
>>>> +
>>>> +int cdns3_is_host(struct cdns3 *cdns)
>>>> +{
>>>> +	if (cdns->current_dr_mode == USB_DR_MODE_HOST)
>>>> +		return 1;
>>>
>>> Why do you need this?
>>
>> I assumed that some SoC could have cut DRD /OTG and Device or Host part.
>> In such case the driver cannot be based on ID pin.
>> For only HOST it's not a problem because
>> the standard XHCI driver will be used.  Probably I will remove this fragment.
> 
> I've removed this condition but it is necessary and I've  restored it again. 
> When driver works in only HOST mode then ID is always 0. 
> For current_dr_mode == USB_DR_MODE_HOST driver has to just simple 
> returns 1.  
> current_dr_mode  can be changed from user space depending on dr_mode field. 

OK.

> 
> I have the additional question. Because I have many changes in source code if I should 
> post the next RFC PATCH v3 or should I wait for comments for rest patches ?

I will need a day to review the remaining patches. So maybe it is better to wait?

> 
>>>
>>>> +	else if (cdns->current_dr_mode == USB_DR_MODE_OTG)
>>>> +		if (!cdns3_otg_get_id(cdns))
>>>> +			return 1;
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
> Thanks,
> Cheers,
> Pawel
> 

cheers,
-roger

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