Re: [PATCH v3 09/12] usb: cdns3: Handle otg mode as peripheral

[Roger Quadros <rogerq@kernel.org>]

On 18/08/2023 21:48, Tom Rini wrote:
> On Thu, Aug 17, 2023 at 11:15:17AM +0300, Roger Quadros wrote:
>> Hi Tom,
>>
>> On 14/08/2023 20:17, Tom Rini wrote:
>>> On Thu, Jul 13, 2023 at 03:45:42PM +0200, Julien Panis wrote:
>>>
>>>> Override 'otg' to 'peripheral' mode, since 'otg' mode
>>>> is not yet supported by u-boot.
>>>>
>>>> Signed-off-by: Julien Panis <jpanis@baylibre.com>
>>>> Suggested-by: Roger Quadros <rogerq@kernel.org>
>>>> ---
>>>>  drivers/usb/cdns3/core.c | 4 ++++
>>>>  1 file changed, 4 insertions(+)
>>>>
>>>> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
>>>> index 644a9791b9c9..bd763fc593e1 100644
>>>> --- a/drivers/usb/cdns3/core.c
>>>> +++ b/drivers/usb/cdns3/core.c
>>>> @@ -149,6 +149,10 @@ static int cdns3_core_init_role(struct cdns3 *cdns)
>>>>  
>>>>  	dr_mode = best_dr_mode;
>>>>  
>>>> +	/* u-boot doesn't yet support OTG so limit to PERIPHERAL */
>>>> +	if (dr_mode == USB_DR_MODE_OTG)
>>>> +		dr_mode = USB_DR_MODE_PERIPHERAL;
>>>> +
>>>>  #if defined(CONFIG_SPL_USB_HOST) || !defined(CONFIG_SPL_BUILD)
>>>>  	if (dr_mode == USB_DR_MODE_OTG || dr_mode == USB_DR_MODE_HOST) {
>>>>  		ret = cdns3_host_init(cdns);
>>>
>>> Julien, why don't we support otg mode here?
>>>
>>
>> dr_mode will never be OTG at this point as the previous if condition
>> would have forced it to PERIPHERAL.
>>
>> My understanding was that u-boot USB framework doesn't support OTG mode
>> so we force it to PERIPHERAL.
> 
> Well, the first part of this series is "make unknown state be OTG" for
> DWC3, so we do in general (and Marek told me off-list he's used it on
> DWC2 as well), so it sounds like these (CDNS3, MUSB) drivers need fixing
> / updating.
> 

CDNS3 does not have an internal OTG state machine. We mostly really care
about role switching and not the full OTG stack. There needs to be
some kind of SW framework to do that in u-boot.

Marek could you please advise what can be done here?

-- 
cheers,
-roger