linux-kernel - Re: [PATCH RESEND v3 04/11] usb: xhci-rcar: convert to readl_poll_timeout

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Date:   Fri, 11 Sep 2020 10:33:21 +0800
From:   Chunfeng Yun <chunfeng.yun@...iatek.com>
To:     Daniel Thompson <daniel.thompson@...aro.org>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Felipe Balbi <balbi@...nel.org>,
        "Matthias Brugger" <matthias.bgg@...il.com>,
        Douglas Anderson <dianders@...omium.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Lee Jones <lee.jones@...aro.org>,
        Sumit Garg <sumit.garg@...aro.org>,
        Jann Horn <jannh@...gle.com>, Arnd Bergmann <arnd@...db.de>,
        Jason Yan <yanaijie@...wei.com>,
        Chuhong Yuan <hslester96@...il.com>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Ben Dooks <ben.dooks@...ethink.co.uk>,
        Saurav Girepunje <saurav.girepunje@...il.com>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
Subject: Re: [PATCH RESEND v3 04/11] usb: xhci-rcar: convert to
 readl_poll_timeout_atomic()

On Thu, 2020-09-10 at 14:12 +0100, Daniel Thompson wrote:
> On Thu, Sep 10, 2020 at 04:21:45PM +0800, Chunfeng Yun wrote:
> > Use readl_poll_timeout_atomic() to simplify code
> > 
> > Cc: Mathias Nyman <mathias.nyman@...ux.intel.com>
> > Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
> > Signed-off-by: Chunfeng Yun <chunfeng.yun@...iatek.com>
> > ---
> > v2~v3: no changes
> > ---
> >  drivers/usb/host/xhci-rcar.c | 43 ++++++++++++-------------------------------
> >  1 file changed, 12 insertions(+), 31 deletions(-)
> > 
> > diff --git a/drivers/usb/host/xhci-rcar.c b/drivers/usb/host/xhci-rcar.c
> > index c1025d3..74f836f 100644
> > --- a/drivers/usb/host/xhci-rcar.c
> > +++ b/drivers/usb/host/xhci-rcar.c
> > @@ -6,6 +6,7 @@
> >   */
> >  
> >  #include <linux/firmware.h>
> > +#include <linux/iopoll.h>
> >  #include <linux/module.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/of.h>
> > @@ -127,8 +128,7 @@ static int xhci_rcar_download_firmware(struct usb_hcd *hcd)
> >  	void __iomem *regs = hcd->regs;
> >  	struct xhci_plat_priv *priv = hcd_to_xhci_priv(hcd);
> >  	const struct firmware *fw;
> > -	int retval, index, j, time;
> > -	int timeout = 10000;
> > +	int retval, index, j;
> >  	u32 data, val, temp;
> >  	u32 quirks = 0;
> >  	const struct soc_device_attribute *attr;
> > @@ -166,32 +166,19 @@ static int xhci_rcar_download_firmware(struct usb_hcd *hcd)
> >  		temp |= RCAR_USB3_DL_CTRL_FW_SET_DATA0;
> >  		writel(temp, regs + RCAR_USB3_DL_CTRL);
> >  
> > -		for (time = 0; time < timeout; time++) {
> > -			val = readl(regs + RCAR_USB3_DL_CTRL);
> > -			if ((val & RCAR_USB3_DL_CTRL_FW_SET_DATA0) == 0)
> > -				break;
> > -			udelay(1);
> > -		}
> > -		if (time == timeout) {
> > -			retval = -ETIMEDOUT;
> > +		retval = readl_poll_timeout_atomic(regs + RCAR_USB3_DL_CTRL,
> > +				val, !(val & RCAR_USB3_DL_CTRL_FW_SET_DATA0),
> > +				1, 10000);
> > +		if (retval < 0)
> >  			break;
> > -		}
> >  	}
> >  
> >  	temp = readl(regs + RCAR_USB3_DL_CTRL);
> >  	temp &= ~RCAR_USB3_DL_CTRL_ENABLE;
> >  	writel(temp, regs + RCAR_USB3_DL_CTRL);
> >  
> > -	for (time = 0; time < timeout; time++) {
> > -		val = readl(regs + RCAR_USB3_DL_CTRL);
> > -		if (val & RCAR_USB3_DL_CTRL_FW_SUCCESS) {
> > -			retval = 0;
> > -			break;
> > -		}
> > -		udelay(1);
> > -	}
> > -	if (time == timeout)
> > -		retval = -ETIMEDOUT;
> > +	retval = readl_poll_timeout_atomic((regs + RCAR_USB3_DL_CTRL),
> > +			val, (val & RCAR_USB3_DL_CTRL_FW_SUCCESS), 1, 10000);
> 
> Directly assigning to retval at this point will clobber a previous
> -ETIMEDOUT error.
> 
> In other words if there is a timeout waiting for FW_SET_DATA0, but not for
> DW_SUCCESS, then we will return the wrong return value.
Yes, agree with you, but seems I keep its original logic unchanged.

Hi Yoshihiro,

  What do think about Daniel's suggestion? should I fix it up?

> 
> 
> Daniel.
> 
> 
> >  
> >  	release_firmware(fw);
> >  
> > @@ -200,18 +187,12 @@ static int xhci_rcar_download_firmware(struct usb_hcd *hcd)
> >  
> >  static bool xhci_rcar_wait_for_pll_active(struct usb_hcd *hcd)
> >  {
> > -	int timeout = 1000;
> > +	int retval;
> >  	u32 val, mask = RCAR_USB3_AXH_STA_PLL_ACTIVE_MASK;
> >  
> > -	while (timeout > 0) {
> > -		val = readl(hcd->regs + RCAR_USB3_AXH_STA);
> > -		if ((val & mask) == mask)
> > -			return true;
> > -		udelay(1);
> > -		timeout--;
> > -	}
> > -
> > -	return false;
> > +	retval = readl_poll_timeout_atomic(hcd->regs + RCAR_USB3_AXH_STA,
> > +			val, ((val & mask) == mask), 1, 1000);
> > +	return !!retval;
> 
> This function returns a bool so !! is either wrong or redundant... I
> think in this case it is wrong and should be a single ! .
Yes, will fix it

Thanks a lot
> 
> 
> Daniel.