linux-kernel - Re: [PATCH v3 12/14] usb: dwc2: Update partial power down entering by system suspend

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Date:   Thu, 8 Apr 2021 13:40:36 +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 12/14] usb: dwc2: Update partial power down entering by
 system suspend

On 4/8/2021 1:45 PM, Artur Petrosyan wrote:
> With current implementation the port power is being disabled,
> which is not required by the programming guide. Also, if there
> is a system which works only in "DWC2_POWER_DOWN_PARAM_NONE"
> (clock gating) mode the current implementation does not set
> Gate hclk bit in pcgctl register.
> 
> Rearranges and updates the implementation of entering to partial
> power down power saving mode when PC is suspended to get
> rid of many "if" statements and removes disabling of port power.
> 
> 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/hcd.c | 53 ++++++++++++++----------------------------
>   1 file changed, 18 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
> index cb52bc41bfb8..34030bafdff4 100644
> --- a/drivers/usb/dwc2/hcd.c
> +++ b/drivers/usb/dwc2/hcd.c
> @@ -4367,8 +4367,6 @@ static int _dwc2_hcd_suspend(struct usb_hcd *hcd)
>   	struct dwc2_hsotg *hsotg = dwc2_hcd_to_hsotg(hcd);
>   	unsigned long flags;
>   	int ret = 0;
> -	u32 hprt0;
> -	u32 pcgctl;
>   
>   	spin_lock_irqsave(&hsotg->lock, flags);
>   
> @@ -4384,47 +4382,32 @@ static int _dwc2_hcd_suspend(struct usb_hcd *hcd)
>   	if (hsotg->op_state == OTG_STATE_B_PERIPHERAL)
>   		goto unlock;
>   
> -	if (hsotg->params.power_down != DWC2_POWER_DOWN_PARAM_PARTIAL ||
> -	    hsotg->flags.b.port_connect_status == 0)
> +	if (hsotg->bus_suspended)
>   		goto skip_power_saving;
>   
> -	/*
> -	 * Drive USB suspend and disable port Power
> -	 * if usb bus is not suspended.
> -	 */
> -	if (!hsotg->bus_suspended) {
> -		hprt0 = dwc2_read_hprt0(hsotg);
> -		if (hprt0 & HPRT0_CONNSTS) {
> -			hprt0 |= HPRT0_SUSP;
> -			if (hsotg->params.power_down == DWC2_POWER_DOWN_PARAM_PARTIAL)
> -				hprt0 &= ~HPRT0_PWR;
> -			dwc2_writel(hsotg, hprt0, HPRT0);
> -		}
> -		if (hsotg->params.power_down == DWC2_POWER_DOWN_PARAM_PARTIAL) {
> -			spin_unlock_irqrestore(&hsotg->lock, flags);
> -			dwc2_vbus_supply_exit(hsotg);
> -			spin_lock_irqsave(&hsotg->lock, flags);
> -		} else {
> -			pcgctl = readl(hsotg->regs + PCGCTL);
> -			pcgctl |= PCGCTL_STOPPCLK;
> -			writel(pcgctl, hsotg->regs + PCGCTL);
> -		}
> -	}
> +	if (hsotg->flags.b.port_connect_status == 0)
> +		goto skip_power_saving;
>   
> -	if (hsotg->params.power_down == DWC2_POWER_DOWN_PARAM_PARTIAL) {
> +	switch (hsotg->params.power_down) {
> +	case DWC2_POWER_DOWN_PARAM_PARTIAL:
>   		/* Enter partial_power_down */
>   		ret = dwc2_enter_partial_power_down(hsotg);
> -		if (ret) {
> -			if (ret != -ENOTSUPP)
> -				dev_err(hsotg->dev,
> -					"enter partial_power_down failed\n");
> -			goto skip_power_saving;
> -		}
> -
> -		/* After entering partial_power_down, hardware is no more accessible */
> +		if (ret)
> +			dev_err(hsotg->dev,
> +				"enter partial_power_down failed\n");
> +		/* After entering suspend, hardware is not accessible */
>   		clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
> +		break;
> +	case DWC2_POWER_DOWN_PARAM_HIBERNATION:
> +	case DWC2_POWER_DOWN_PARAM_NONE:
> +	default:
> +		goto skip_power_saving;
>   	}
>   
> +	spin_unlock_irqrestore(&hsotg->lock, flags);
> +	dwc2_vbus_supply_exit(hsotg);
> +	spin_lock_irqsave(&hsotg->lock, flags);
> +
>   	/* Ask phy to be suspended */
>   	if (!IS_ERR_OR_NULL(hsotg->uphy)) {
>   		spin_unlock_irqrestore(&hsotg->lock, flags);
>