linux-kernel - Re: [PATCH 1/1] usb: dwc2: gadget: don't try to disable ep0 in dwc2_hsotg

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Date:   Thu, 16 Dec 2021 10:18:41 +0000
From:   Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
To:     Amelie DELAUNAY <amelie.delaunay@...s.st.com>,
        Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        Fabrice Gasnier <fabrice.gasnier@...s.st.com>
Subject: Re: [PATCH 1/1] usb: dwc2: gadget: don't try to disable ep0 in
 dwc2_hsotg_suspend

Hi Amelie,

On 12/14/2021 4:53 PM, Amelie DELAUNAY wrote:
> Hi Minas,
> 
> On 12/14/21 7:22 AM, Minas Harutyunyan wrote:
>> Hi Amelie,
>>
>> On 12/7/2021 5:01 PM, Amelie Delaunay wrote:
>>> Calling dwc2_hsotg_ep_disable on ep0 (in/out) will lead to the following
>>> logs before returning -EINVAL:
>>> dwc2 49000000.usb-otg: dwc2_hsotg_ep_disable: called for ep0
>>> dwc2 49000000.usb-otg: dwc2_hsotg_ep_disable: called for ep0
>>>
>>
>> This messages printed for EP0 OUT which can't be disabled, but EP0 IN
>> can and should be disabled. Your patch exclude EP0 IN from disabling 
>> flow.
> 
> 
> Thanks for the review. I wonder why then in dwc2_hsotg_udc_stop and 
> dwc2_hsotg_core_init_disconnected EP0 IN is not disabled (loop starts 
> from EP1) ?
> 
> Due to:
>      /* Same dwc2_hsotg_ep is used in both directions for ep0 */
>      hsotg->eps_out[0] = hsotg->eps_in[0];

Yes, I missed this.

Actually, there very small probabilities that EP0 IN will be enabled 
when performing stop_udc or suspend. So, I'm going to ACK your initial 
patch.

Thanks,
Minas

> 
> the condition in dwc2_hsotg_ep_disable to display the error is always 
> true for EP0, whatever the direction, so the log appears for EP0 IN & OUT:
>      if (ep == &hsotg->eps_out[0]->ep) {
>          dev_err(hsotg->dev, "%s: called for ep0\n", __func__);
>          return -EINVAL;
>      }
> 
> Should all loops need to be fixed to start loop from EP0 but exclude EP0 
> OUT from being disabled, so that EP0 IN can be disabled ? e.g. for 
> dwc2_hsotg_suspend:
> 
> 
> $ git diff drivers/usb/dwc2/gadget.c
> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> index 11d85a6e0b0d..0c12219bfbf4 100644
> --- a/drivers/usb/dwc2/gadget.c
> +++ b/drivers/usb/dwc2/gadget.c
> @@ -4231,7 +4231,7 @@ static int dwc2_hsotg_ep_disable(struct usb_ep *ep)
> 
>          dev_dbg(hsotg->dev, "%s(ep %p)\n", __func__, ep);
> 
> -       if (ep == &hsotg->eps_out[0]->ep) {
> +       if (ep == &hsotg->eps_out[0]->ep && !dir_in) {
>                  dev_err(hsotg->dev, "%s: called for ep0\n", __func__);
>                  return -EINVAL;
>          }
> @@ -5077,7 +5077,7 @@ int dwc2_hsotg_suspend(struct dwc2_hsotg *hsotg)
>                  for (ep = 0; ep < hsotg->num_of_eps; ep++) {
>                          if (hsotg->eps_in[ep])
> 
> dwc2_hsotg_ep_disable_lock(&hsotg->eps_in[ep]->ep);
> -                       if (hsotg->eps_out[ep])
> +                       if (ep > 0 && hsotg->eps_out[ep])
> 
> dwc2_hsotg_ep_disable_lock(&hsotg->eps_out[ep]->ep);
>                  }
>          }
> 
> Regards,
> Amelie
> 
>>
>> Thanks,
>> Minas
>>
>>> To avoid these two logs while suspending, start disabling the endpoint
>>> from the index 1, as done in dwc2_hsotg_udc_stop:
>>>
>>>     /* all endpoints should be shutdown */
>>>     for (ep = 1; ep < hsotg->num_of_eps; ep++) {
>>>         if (hsotg->eps_in[ep])
>>>             dwc2_hsotg_ep_disable_lock(&hsotg->eps_in[ep]->ep);
>>>         if (hsotg->eps_out[ep])
>>>             dwc2_hsotg_ep_disable_lock(&hsotg->eps_out[ep]->ep);
>>>     }
>>>
>>> Signed-off-by: Amelie Delaunay <amelie.delaunay@...s.st.com>
>>> ---
>>>    drivers/usb/dwc2/gadget.c | 2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
>>> index b884a83b26a6..ee31f9a328da 100644
>>> --- a/drivers/usb/dwc2/gadget.c
>>> +++ b/drivers/usb/dwc2/gadget.c
>>> @@ -5086,7 +5086,7 @@ int dwc2_hsotg_suspend(struct dwc2_hsotg *hsotg)
>>>            hsotg->gadget.speed = USB_SPEED_UNKNOWN;
>>>            spin_unlock_irqrestore(&hsotg->lock, flags);
>>> -        for (ep = 0; ep < hsotg->num_of_eps; ep++) {
>>> +        for (ep = 1; ep < hsotg->num_of_eps; ep++) {
>>>                if (hsotg->eps_in[ep])
>>>                    dwc2_hsotg_ep_disable_lock(&hsotg->eps_in[ep]->ep);
>>>                if (hsotg->eps_out[ep])
>>