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 16:16:40 +0000
From:   Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
To:     Fabrice Gasnier <fabrice.gasnier@...com>,
        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

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.

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