linux-kernel - Re: [PATCH 3/3] usb: cdns3: Enable workaround for USB2.0 PHY Rx compliance test PHY lockup

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Date:   Thu, 27 Aug 2020 11:09:54 +0000
From:   Peter Chen <peter.chen@....com>
To:     Roger Quadros <rogerq@...com>
CC:     "balbi@...nel.org" <balbi@...nel.org>,
        "pawell@...ence.com" <pawell@...ence.com>,
        "kurahul@...ence.com" <kurahul@...ence.com>,
        "nsekhar@...com" <nsekhar@...com>,
        "vigneshr@...com" <vigneshr@...com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH 3/3] usb: cdns3: Enable workaround for USB2.0 PHY Rx
 compliance test PHY lockup

On 20-08-25 15:00:59, Roger Quadros wrote:
> From: Pawel Laszczak <pawell@...ence.com>
> 
> USB2.0 PHY hangs in Rx Compliance test when the incoming packet
> amplitude is varied below and above the Squelch Level of
> Receiver during the active packet multiple times.
> 
> Version 1 of the controller allows PHY to be reset when RX fail condition
> is detected to work around the above issue. This feature is
> disabled by default and needs to be enabled using a bit from
> the newly added PHYRST_CFG register. This patch enables the workaround.
> 
> As there is no way to distinguish between the controller version
> before the device controller is started we need to rely on a
> DT property to decide when to apply the workaround.
> 
> Signed-off-by: Pawel Laszczak <pawell@...ence.com>
> Signed-off-by: Roger Quadros <rogerq@...com>

Reviewed-by: Peter Chen <peter.chen@....com>

Peter
> ---
>  drivers/usb/cdns3/core.c |  2 ++
>  drivers/usb/cdns3/core.h |  1 +
>  drivers/usb/cdns3/drd.c  | 12 ++++++++++++
>  drivers/usb/cdns3/drd.h  |  5 ++++-
>  4 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
> index 5c1586ec7824..34b36487682b 100644
> --- a/drivers/usb/cdns3/core.c
> +++ b/drivers/usb/cdns3/core.c
> @@ -443,6 +443,8 @@ static int cdns3_probe(struct platform_device *pdev)
>  		return -ENXIO;
>  	}
>  
> +	cdns->phyrst_a_enable = device_property_read_bool(dev, "cdns,phyrst-a-enable");
> +
>  	cdns->otg_res = *res;
>  
>  	mutex_init(&cdns->mutex);
> diff --git a/drivers/usb/cdns3/core.h b/drivers/usb/cdns3/core.h
> index 1ad1f1fe61e9..24cf0f1b5726 100644
> --- a/drivers/usb/cdns3/core.h
> +++ b/drivers/usb/cdns3/core.h
> @@ -76,6 +76,7 @@ struct cdns3 {
>  #define CDNS3_CONTROLLER_V0	0
>  #define CDNS3_CONTROLLER_V1	1
>  	u32				version;
> +	bool				phyrst_a_enable;
>  
>  	int				otg_irq;
>  	int				dev_irq;
> diff --git a/drivers/usb/cdns3/drd.c b/drivers/usb/cdns3/drd.c
> index 6234bcd6158a..b74803e9703d 100644
> --- a/drivers/usb/cdns3/drd.c
> +++ b/drivers/usb/cdns3/drd.c
> @@ -42,6 +42,18 @@ int cdns3_set_mode(struct cdns3 *cdns, enum usb_dr_mode mode)
>  			reg = readl(&cdns->otg_v1_regs->override);
>  			reg |= OVERRIDE_IDPULLUP;
>  			writel(reg, &cdns->otg_v1_regs->override);
> +
> +			/*
> +			 * Enable work around feature built into the
> +			 * controller to address issue with RX Sensitivity
> +			 * est (EL_17) for USB2 PHY. The issue only occures
> +			 * for 0x0002450D controller version.
> +			 */
> +			if (cdns->phyrst_a_enable) {
> +				reg = readl(&cdns->otg_v1_regs->phyrst_cfg);
> +				reg |= PHYRST_CFG_PHYRST_A_ENABLE;
> +				writel(reg, &cdns->otg_v1_regs->phyrst_cfg);
> +			}
>  		} else {
>  			reg = readl(&cdns->otg_v0_regs->ctrl1);
>  			reg |= OVERRIDE_IDPULLUP_V0;
> diff --git a/drivers/usb/cdns3/drd.h b/drivers/usb/cdns3/drd.h
> index 7e7cf7fa2dd3..f1ccae285a16 100644
> --- a/drivers/usb/cdns3/drd.h
> +++ b/drivers/usb/cdns3/drd.h
> @@ -31,7 +31,7 @@ struct cdns3_otg_regs {
>  	__le32 simulate;
>  	__le32 override;
>  	__le32 susp_ctrl;
> -	__le32 reserved4;
> +	__le32 phyrst_cfg;
>  	__le32 anasts;
>  	__le32 adp_ramp_time;
>  	__le32 ctrl1;
> @@ -153,6 +153,9 @@ struct cdns3_otg_common_regs {
>  /* Only for CDNS3_CONTROLLER_V0 version */
>  #define OVERRIDE_IDPULLUP_V0		BIT(24)
>  
> +/* PHYRST_CFG - bitmasks */
> +#define PHYRST_CFG_PHYRST_A_ENABLE     BIT(0)
> +
>  #define CDNS3_ID_PERIPHERAL		1
>  #define CDNS3_ID_HOST			0
>  
> -- 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
> 

-- 

Thanks,
Peter Chen