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

Peter Chen
2020-08-26T03:21:12Z

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 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.

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.

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 = 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