linux-kernel - Re: [PATCH] usb: dwc2: use a longer AHB idle timeout in dwc2_core

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Date:   Mon, 24 Jun 2019 09:41:46 +0400
From:   Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "felipe.balbi@...ux.intel.com" <felipe.balbi@...ux.intel.com>
Cc:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-stable <stable@...r.kernel.org>
Subject: Re: [PATCH] usb: dwc2: use a longer AHB idle timeout in
 dwc2_core_reset()

On 6/20/2019 9:51 PM, Martin Blumenstingl wrote:
> Use a 10000us AHB idle timeout in dwc2_core_reset() and make it
> consistent with the other "wait for AHB master IDLE state" ocurrences.
> 
> This fixes a problem for me where dwc2 would not want to initialize when
> updating to 4.19 on a MIPS Lantiq VRX200 SoC. dwc2 worked fine with
> 4.14.
> Testing on my board shows that it takes 180us until AHB master IDLE
> state is signalled. The very old vendor driver for this SoC (ifxhcd)
> used a 1 second timeout.
> Use the same timeout that is used everywhere when polling for
> GRSTCTL_AHBIDLE instead of using a timeout that "works for one board"
> (180us in my case) to have consistent behavior across the dwc2 driver.
> 
> Cc: linux-stable <stable@...r.kernel.org> # 4.19+
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
> ---

Acked-by: Minas Harutyunyan <hminas@...opsys.com>

>   drivers/usb/dwc2/core.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c
> index 8b499d643461..8e41d70fd298 100644
> --- a/drivers/usb/dwc2/core.c
> +++ b/drivers/usb/dwc2/core.c
> @@ -531,7 +531,7 @@ int dwc2_core_reset(struct dwc2_hsotg *hsotg, bool skip_wait)
>   	}
>   
>   	/* Wait for AHB master IDLE state */
> -	if (dwc2_hsotg_wait_bit_set(hsotg, GRSTCTL, GRSTCTL_AHBIDLE, 50)) {
> +	if (dwc2_hsotg_wait_bit_set(hsotg, GRSTCTL, GRSTCTL_AHBIDLE, 10000)) {
>   		dev_warn(hsotg->dev, "%s: HANG! AHB Idle timeout GRSTCTL GRSTCTL_AHBIDLE\n",
>   			 __func__);
>   		return -EBUSY;
>