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

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Date:   Thu, 10 Sep 2020 14:12:12 +0100
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Chunfeng Yun <chunfeng.yun@...iatek.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, 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.


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 ! .


Daniel.