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 14:48:52 +0000
From:   Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
To:     Fabrice Gasnier <fabrice.gasnier@...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 4/21/2020 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;
                         call_gadget(hsotg, resume);
                 }
                 /* Change to L0 state */


Thanks,
Minas