[PATCH v1] usb: dwc3: core: Fix timeout check

[Varadarajan Narayanan]

On Sun, Jan 12, 2025 at 09:48:41PM +0100, Marek Vasut wrote:
> On 1/10/25 8:43 AM, Varadarajan Narayanan wrote:
> > dwc3_core_init loops 'timeout' times to check if the IP block is out
> > of reset using 'while (timeout--)'. If there is some issue and
> > the block doesn't come out of reset, the loop will run till
> > 'timeout' becomes zero and the post decrement operator would set
> > timeout to 0xffffffff. Though the IP block is not out reset, the
> > subsequent if check 'if !timeout' would fail as timeout is not
> > equal to zero and the function proceeds with the initialization.
> >
> > Make this a pre decrement to address this.
> >
> > Signed-off-by: Varadarajan Narayanan <quic_varada at quicinc.com>
> Does the following patch work too ? It removes all the fragile open-coded
> polling
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index a35b8c2f646..7e7017d4be7 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -29,6 +29,7 @@
>  #include <linux/usb/ch9.h>
>  #include <linux/usb/gadget.h>
>  #include <linux/bitfield.h>
> +#include <linux/iopoll.h>
>  #include <linux/math64.h>
>  #include <linux/time.h>
>
> @@ -587,7 +588,6 @@ static void dwc3_set_incr_burst_type(struct dwc3 *dwc)
>   */
>  static int dwc3_core_init(struct dwc3 *dwc)
>  {
> -	unsigned long		timeout;
>  	u32			hwparams4 = dwc->hwparams.hwparams4;
>  	u32			reg;
>  	int			ret;
> @@ -610,17 +610,12 @@ static int dwc3_core_init(struct dwc3 *dwc)
>  	}
>
>  	/* issue device SoftReset too */
> -	timeout = 5000;
>  	dwc3_writel(dwc->regs, DWC3_DCTL, DWC3_DCTL_CSFTRST);
> -	while (timeout--) {
> -		reg = dwc3_readl(dwc->regs, DWC3_DCTL);
> -		if (!(reg & DWC3_DCTL_CSFTRST))
> -			break;
> -	};
> -
> -	if (!timeout) {
> +	ret = read_poll_timeout(dwc3_readl, reg,
> +				!(reg & DWC3_DCTL_CSFTRST),
> +				1, 5000, dwc->regs, DWC3_DCTL);
> +	if (ret) {
>  		dev_err(dwc->dev, "Reset Timed Out\n");
> -		ret = -ETIMEDOUT;
>  		goto err0;
>  	}

This worked too.

Tested-By: Varadarajan Narayanan <quic_varada at quicinc.com>

Thanks
Varada