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From:   Pawel Laszczak <pawell@cadence.com>
To:     Peter Chen <peter.chen@nxp.com>, Roger Quadros <rogerq@ti.com>
CC:     "balbi@kernel.org" <balbi@kernel.org>,
        Rahul Kumar <kurahul@cadence.com>,
        "nsekhar@ti.com" <nsekhar@ti.com>,
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        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Subject: RE: [PATCH 3/3] usb: cdns3: Enable workaround for USB2.0 PHY Rx
 compliance test PHY lockup
Thread-Topic: [PATCH 3/3] usb: cdns3: Enable workaround for USB2.0 PHY Rx
 compliance test PHY lockup
Thread-Index: AQHWetduJTzcjYjglUaGSk5K6slNnalJuioAgAALt3A=
Date:   Wed, 26 Aug 2020 04:04:01 +0000
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References: <20200825120059.12436-1-rogerq@ti.com>
 <20200825120059.12436-4-rogerq@ti.com> <20200826031948.GA7646@b29397-desktop>
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>On 20-08-25 15:00:59, Roger Quadros wrote:
>> From: Pawel Laszczak <pawell@cadence.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 conditio=
n
>> 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.
>
>Pawel, it could know the controller version at cdns3_gadget_start,
>but the controller starts when it tries to bind gadget driver, at that
>time, it has already known the controller version.
>
>For me, the device controller starts is using USB_CONF.DEVEN (Device
>Enable) through usb_gadget_connect, I am not sure if it is the same
>with yours.
>

Yes in device mode driver knows controller version but this workaround=20
Must be enabled also in host mode. In host mode the controller=20
doesn't have access to device registers. The controller version is=20
placed in device register.

Pawel

>Peter
>
>
>>
>> Signed-off-by: Pawel Laszczak <pawell@cadence.com>
>> Signed-off-by: Roger Quadros <rogerq@ti.com>
>> ---
>>  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 =3D device_property_read_bool(dev, "cdns,phyrst-=
a-enable");
>> +
>>  	cdns->otg_res =3D *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_mo=
de mode)
>>  			reg =3D readl(&cdns->otg_v1_regs->override);
>>  			reg |=3D 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 =3D readl(&cdns->otg_v1_regs->phyrst_cfg);
>> +				reg |=3D PHYRST_CFG_PHYRST_A_ENABLE;
>> +				writel(reg, &cdns->otg_v1_regs->phyrst_cfg);
>> +			}
>>  		} else {
>>  			reg =3D readl(&cdns->otg_v0_regs->ctrl1);
>>  			reg |=3D 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