linux-kernel - Re: [PATCH v3 07/14] usb: dwc2: Add exit partial power down when port is resumed

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Date:   Thu, 8 Apr 2021 13:39:46 +0000
From:   Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
To:     Artur Petrosyan <Arthur.Petrosyan@...opsys.com>,
        Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     John Youn <John.Youn@...opsys.com>
Subject: Re: [PATCH v3 07/14] usb: dwc2: Add exit partial power down when port
 is resumed

On 4/8/2021 1:45 PM, Artur Petrosyan wrote:
> Added flow of exiting Partial Power Down in
> "dwc2_port_resume()" function when core receives resume.
> 
> NOTE: Switch case statement is used for hibernation partial
> power down and clock gating mode determination. In this patch
> only Partial Power Down is implemented the Hibernation and
> clock gating implementations are planned to be added.
> 
> Signed-off-by: Artur Petrosyan <Arthur.Petrosyan@...opsys.com>

Acked-by: Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>

> ---
>   Changes in v3:
>   - None
>   Changes in v2:
>   - None
> 
>   drivers/usb/dwc2/core.h |  5 ++--
>   drivers/usb/dwc2/hcd.c  | 61 ++++++++++++++++++++++++++---------------
>   2 files changed, 42 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
> index 76807abd753b..5a7850482e57 100644
> --- a/drivers/usb/dwc2/core.h
> +++ b/drivers/usb/dwc2/core.h
> @@ -1471,7 +1471,7 @@ void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg, bool force);
>   void dwc2_hcd_start(struct dwc2_hsotg *hsotg);
>   int dwc2_core_init(struct dwc2_hsotg *hsotg, bool initial_setup);
>   int dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex);
> -void dwc2_port_resume(struct dwc2_hsotg *hsotg);
> +int dwc2_port_resume(struct dwc2_hsotg *hsotg);
>   int dwc2_backup_host_registers(struct dwc2_hsotg *hsotg);
>   int dwc2_restore_host_registers(struct dwc2_hsotg *hsotg);
>   int dwc2_host_enter_hibernation(struct dwc2_hsotg *hsotg);
> @@ -1497,7 +1497,8 @@ static inline int dwc2_core_init(struct dwc2_hsotg *hsotg, bool initial_setup)
>   { return 0; }
>   static inline int dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex)
>   { return 0; }
> -static inline void dwc2_port_resume(struct dwc2_hsotg *hsotg) {}
> +static inline int dwc2_port_resume(struct dwc2_hsotg *hsotg)
> +{ return 0; }
>   static inline int dwc2_hcd_init(struct dwc2_hsotg *hsotg)
>   { return 0; }
>   static inline int dwc2_backup_host_registers(struct dwc2_hsotg *hsotg)
> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
> index e7fb0d5940bc..720354df014b 100644
> --- a/drivers/usb/dwc2/hcd.c
> +++ b/drivers/usb/dwc2/hcd.c
> @@ -3353,44 +3353,61 @@ int dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex)
>    *
>    * @hsotg: Programming view of the DWC_otg controller
>    *
> + * Return: non-zero if failed to exit suspend mode for host.
> + *
>    * This function is for exiting Host mode suspend.
>    * Must NOT be called with interrupt disabled or spinlock held.
>    */
> -void dwc2_port_resume(struct dwc2_hsotg *hsotg)
> +int dwc2_port_resume(struct dwc2_hsotg *hsotg)
>   {
>   	unsigned long flags;
>   	u32 hprt0;
>   	u32 pcgctl;
> +	int ret = 0;
>   
>   	spin_lock_irqsave(&hsotg->lock, flags);
>   
> -	/*
> -	 * If power_down is supported, Phy clock is already resumed
> -	 * after registers restore.
> -	 */
> -	if (!hsotg->params.power_down) {
> -		pcgctl = dwc2_readl(hsotg, PCGCTL);
> -		pcgctl &= ~PCGCTL_STOPPCLK;
> -		dwc2_writel(hsotg, pcgctl, PCGCTL);
> +	switch (hsotg->params.power_down) {
> +	case DWC2_POWER_DOWN_PARAM_PARTIAL:
> +		ret = dwc2_exit_partial_power_down(hsotg, 0, true);
> +		if (ret)
> +			dev_err(hsotg->dev,
> +				"exit partial_power_down failed.\n");
> +		break;
> +	case DWC2_POWER_DOWN_PARAM_HIBERNATION:
> +	case DWC2_POWER_DOWN_PARAM_NONE:
> +	default:
> +		/*
> +		 * If power_down is supported, Phy clock is already resumed
> +		 * after registers restore.
> +		 */
> +		if (!hsotg->params.power_down) {
> +			pcgctl = dwc2_readl(hsotg, PCGCTL);
> +			pcgctl &= ~PCGCTL_STOPPCLK;
> +			dwc2_writel(hsotg, pcgctl, PCGCTL);
> +			spin_unlock_irqrestore(&hsotg->lock, flags);
> +			msleep(20);
> +			spin_lock_irqsave(&hsotg->lock, flags);
> +		}
> +
> +		hprt0 = dwc2_read_hprt0(hsotg);
> +		hprt0 |= HPRT0_RES;
> +		hprt0 &= ~HPRT0_SUSP;
> +		dwc2_writel(hsotg, hprt0, HPRT0);
>   		spin_unlock_irqrestore(&hsotg->lock, flags);
> -		msleep(20);
> +
> +		msleep(USB_RESUME_TIMEOUT);
> +
>   		spin_lock_irqsave(&hsotg->lock, flags);
> +		hprt0 = dwc2_read_hprt0(hsotg);
> +		hprt0 &= ~(HPRT0_RES | HPRT0_SUSP);
> +		dwc2_writel(hsotg, hprt0, HPRT0);
> +		hsotg->bus_suspended = false;
>   	}
>   
> -	hprt0 = dwc2_read_hprt0(hsotg);
> -	hprt0 |= HPRT0_RES;
> -	hprt0 &= ~HPRT0_SUSP;
> -	dwc2_writel(hsotg, hprt0, HPRT0);
>   	spin_unlock_irqrestore(&hsotg->lock, flags);
>   
> -	msleep(USB_RESUME_TIMEOUT);
> -
> -	spin_lock_irqsave(&hsotg->lock, flags);
> -	hprt0 = dwc2_read_hprt0(hsotg);
> -	hprt0 &= ~(HPRT0_RES | HPRT0_SUSP);
> -	dwc2_writel(hsotg, hprt0, HPRT0);
> -	hsotg->bus_suspended = false;
> -	spin_unlock_irqrestore(&hsotg->lock, flags);
> +	return ret;
>   }
>   
>   /* Handles hub class-specific requests */
>