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

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Date:   Wed, 22 Apr 2020 17:57:08 +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 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
>