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From:   Pawel Laszczak <pawell@cadence.com>
To:     Peter Chen <peter.chen@nxp.com>
CC:     Roger Quadros <rogerq@ti.com>,
        "balbi@kernel.org" <balbi@kernel.org>,
        Rahul Kumar <kurahul@cadence.com>,
        "nsekhar@ti.com" <nsekhar@ti.com>,
        "vigneshr@ti.com" <vigneshr@ti.com>,
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        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "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: AQHWetduJTzcjYjglUaGSk5K6slNnalJuioAgAALt3CAADYFAIAAAhIQ
Date:   Wed, 26 Aug 2020 07:44:45 +0000
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>
>On 20-08-26 04:04:01, Pawel Laszczak wrote:
>> >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 condi=
tion
>> >> 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 workaroun=
d.
>> >>
>> >> 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
>> Must be enabled also in host mode. In host mode the controller
>> doesn't have access to device registers. The controller version is
>> placed in device register.
>>
>
>You may suggest your design team adding CHIP_VER register at global
>register region, it will easy the software engineer life.
>
>From what I read, this register is only enabling USB2 PHY reset software
>control, it needs for all chips with rev 0x0002450D, and the place you
>current change is only for 0x0002450D, right?

Even I could say that this workaround should be enabled only for=20
Specific USB2 PHY  (only 0x0002450D)

This bit should not have any impact for Cadence PHY but it can has=20
Impact for third party PHYs.
=20
Pawel

>
>Peter
>
>> 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 *pd=
ev)
>> >>  		return -ENXIO;
>> >>  	}
>> >>
>> >> +	cdns->phyrst_a_enable =3D device_property_read_bool(dev, "cdns,phyr=
st-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=
_mode 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
>
>--
>
>Thanks,
>Peter Chen