linux-kernel - Re: [PATCH] usb: dwc2: host: use msleep() for long delays

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Date:   Thu, 12 Jan 2017 16:40:09 -0800
From:   John Youn <John.Youn@...opsys.com>
To:     Nicholas Mc Guire <hofrat@...dl.org>,
        John Youn <John.Youn@...opsys.com>,
        Felipe Balbi <balbi@...nel.org>
CC:     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>
Subject: Re: [PATCH] usb: dwc2: host: use msleep() for long delays

On 1/12/2017 7:52 AM, Nicholas Mc Guire wrote:
> ulseep_range() uses hrtimers and provides no advantage over msleep()
> for larger delays. Fix up the 20+ ms delays here passing the adjusted "min"
> value to msleep(). This helps reduce the load on the hrtimer subsystem.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> ---
> 
> Patch was compile tested with: x86_64_defconfig + CONFIG_USB_DWC2
> (1 sparse and 6 coccinelle warning - preparing separate patches for that)
> 
> Patch is against 4.10-rc3 (localversion-next is next-20170112)
> 
>  drivers/usb/dwc2/hcd.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
> index 911c3b3..37ee72d 100644
> --- a/drivers/usb/dwc2/hcd.c
> +++ b/drivers/usb/dwc2/hcd.c
> @@ -2150,7 +2150,7 @@ static int dwc2_hcd_endpoint_disable(struct dwc2_hsotg *hsotg,
>  		}
>  
>  		spin_unlock_irqrestore(&hsotg->lock, flags);
> -		usleep_range(20000, 40000);
> +		msleep(20);
>  		spin_lock_irqsave(&hsotg->lock, flags);
>  		qh = ep->hcpriv;
>  		if (!qh) {
> @@ -3240,7 +3240,7 @@ static void dwc2_conn_id_status_change(struct work_struct *work)
>  				 "Waiting for Peripheral Mode, Mode=%s\n",
>  				 dwc2_is_host_mode(hsotg) ? "Host" :
>  				 "Peripheral");
> -			usleep_range(20000, 40000);
> +			msleep(20);
>  			if (++count > 250)
>  				break;
>  		}
> @@ -3261,7 +3261,7 @@ static void dwc2_conn_id_status_change(struct work_struct *work)
>  			dev_info(hsotg->dev, "Waiting for Host Mode, Mode=%s\n",
>  				 dwc2_is_host_mode(hsotg) ?
>  				 "Host" : "Peripheral");
> -			usleep_range(20000, 40000);
> +			msleep(20);
>  			if (++count > 250)
>  				break;
>  		}
> @@ -3354,7 +3354,7 @@ static void dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex)
>  
>  		spin_unlock_irqrestore(&hsotg->lock, flags);
>  
> -		usleep_range(200000, 250000);
> +		msleep(200);
>  	} else {
>  		spin_unlock_irqrestore(&hsotg->lock, flags);
>  	}
> @@ -3378,7 +3378,7 @@ static void dwc2_port_resume(struct dwc2_hsotg *hsotg)
>  		pcgctl &= ~PCGCTL_STOPPCLK;
>  		dwc2_writel(pcgctl, hsotg->regs + PCGCTL);
>  		spin_unlock_irqrestore(&hsotg->lock, flags);
> -		usleep_range(20000, 40000);
> +		msleep(20);
>  		spin_lock_irqsave(&hsotg->lock, flags);
>  	}
>  
> @@ -3691,7 +3691,7 @@ static int dwc2_hcd_hub_control(struct dwc2_hsotg *hsotg, u16 typereq,
>  			}
>  
>  			/* Clear reset bit in 10ms (FS/LS) or 50ms (HS) */
> -			usleep_range(50000, 70000);
> +			msleep(50);
>  			hprt0 &= ~HPRT0_RST;
>  			dwc2_writel(hprt0, hsotg->regs + HPRT0);
>  			hsotg->lx_state = DWC2_L0; /* Now back to On state */
> 

+Felipe

Acked-by: John Youn <johnyoun@...opsys.com>

I've also fixed this up locally to apply against recent dwc2 patches
for next.

Hi Felipe,

If/when you queue the pending dwc2 patches on testing/next I can
resend this to you.

Regards,
John