linux-kernel - Re: [PATCH 1/4] usb: dwc2: gadget: move gadget resume after the core is in L0 state

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Message-ID: <d1a2ce55-450b-47ea-15f9-a8532000a647@st.com>
Date:   Thu, 23 Apr 2020 11:27:33 +0200
From:   Fabrice Gasnier <fabrice.gasnier@...com>
To:     Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>,
        "balbi@...nel.org" <balbi@...nel.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>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "amelie.delaunay@...com" <amelie.delaunay@...com>
Subject: Re: [PATCH 1/4] usb: dwc2: gadget: move gadget resume after the core
 is in L0 state

On 4/22/20 6:16 PM, Minas Harutyunyan wrote:
> Hi Fabrice,
> 
> On 4/22/2020 7:57 PM, Fabrice Gasnier wrote:
>> On 4/22/20 4:48 PM, Minas Harutyunyan wrote:
>>> Hi Fabrice,
>>>
>>> On 4/21/2020 4:32 PM, Fabrice Gasnier wrote:
>>>> When the remote wakeup interrupt is triggered, lx_state is resumed from L2
>>>> to L0 state. But when the gadget resume is called, lx_state is still L2.
>>>> This prevents the resume callback to queue any request. Any attempt
>>>> to queue a request from resume callback will result in:
>>>> - "submit request only in active state" debug message to be issued
>>>> - dwc2_hsotg_ep_queue() returns -EAGAIN
>>>>
>>>> Move the call to resume gadget after the core is put in DWC2_L0 state.
>>>>
>>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...com>
>>>> ---
>>>>    drivers/usb/dwc2/core_intr.c | 10 +++++++---
>>>>    1 file changed, 7 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
>>>> index 876ff31..b8ebda5 100644
>>>> --- a/drivers/usb/dwc2/core_intr.c
>>>> +++ b/drivers/usb/dwc2/core_intr.c
>>>> @@ -404,9 +404,11 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
>>>>    	}
>>>>    
>>>>    	if (dwc2_is_device_mode(hsotg)) {
>>>> +		enum dwc2_lx_state lx_state = hsotg->lx_state;
>>>> +
>>>>    		dev_dbg(hsotg->dev, "DSTS=0x%0x\n",
>>>>    			dwc2_readl(hsotg, DSTS));
>>>> -		if (hsotg->lx_state == DWC2_L2) {
>>>> +		if (lx_state == DWC2_L2) {
>>>>    			u32 dctl = dwc2_readl(hsotg, DCTL);
>>>>    
>>>>    			/* Clear Remote Wakeup Signaling */
>>>> @@ -415,11 +417,13 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
>>>>    			ret = dwc2_exit_partial_power_down(hsotg, true);
>>>>    			if (ret && (ret != -ENOTSUPP))
>>>>    				dev_err(hsotg->dev, "exit power_down failed\n");
>>>> -
>>>> -			call_gadget(hsotg, resume);
>>>>    		}
>>>>    		/* Change to L0 state */
>>>>    		hsotg->lx_state = DWC2_L0;
>>>> +
>>>> +		/* Gadget may queue new requests upon resume to L0 state */
>>>> +		if (lx_state == DWC2_L2)
>>>> +			call_gadget(hsotg, resume);
>>>>    	} else {
>>>>    		if (hsotg->params.power_down)
>>>>    			return;
>>>>
>>>
>>> What about below patch without introducing additional variable.
>>>
>>> diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
>>> index 876ff31261d5..543865e31c72 100644
>>> --- a/drivers/usb/dwc2/core_intr.c
>>> +++ b/drivers/usb/dwc2/core_intr.c
>>> @@ -416,6 +416,8 @@ static void dwc2_handle_wakeup_detected_intr(struct
>>> dwc2_hsotg *hsotg)
>>>                           if (ret && (ret != -ENOTSUPP))
>>>                                   dev_err(hsotg->dev, "exit power_down
>>> failed\n");
>>>
>>> +                       /* Change to L0 state */
>>> +                       hsotg->lx_state = DWC2_L0;
>>
>> Hi Minas,
>>
>> That was my first approach locally, but I added a variable to avoid do
>> it twice... few lines after.
>>
>> But if you prefer, I can change in V2 ?
>>
>> Please let me know.
>>
>> Thanks,
>> Fabrice
>>
>>>                           call_gadget(hsotg, resume);
>>>                   }
>>>                   /* Change to L0 state */
>>>
>>>
>>> Thanks,
>>> Minas
>>>
> To avoid twice setting lx_state you can add 'else' before second setting.

Hi Minas,

Thanks for your quick answer. Sure, I'll update it in v2.

Also, do you think this can/should be marked as a fix ?
- e.g. add a Fixes tag?

Fixes: f81f46e1f530 ("usb: dwc2: implement hibernation during bus
suspend/resume")

Please advise,
Best Regards,
Fabrice

> 
> diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
> index 876ff31261d5..f59dabd46e60 100644
> --- a/drivers/usb/dwc2/core_intr.c
> +++ b/drivers/usb/dwc2/core_intr.c
> @@ -416,10 +416,14 @@ static void 
> dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
>                          if (ret && (ret != -ENOTSUPP))
>                                  dev_err(hsotg->dev, "exit power_down 
> failed\n");
> 
> +                       /* Change to L0 state */
> +                       hsotg->lx_state = DWC2_L0;
>                          call_gadget(hsotg, resume);
>                  }
> -               /* Change to L0 state */
> -               hsotg->lx_state = DWC2_L0;
> +               else {
> +                       /* Change to L0 state */
> +                       hsotg->lx_state = DWC2_L0;
> +               }
>          } else {
>                  if (hsotg->params.power_down)
>                          return;
> 
> 
> 
> Am I missed something?
> 
> Thanks,
> Minas
>