linux-kernel - Re: [PATCH v2 3/4] usb: typec: tcpci: clear the fault status bit

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Message-ID: <6a894ff0-3232-4ef0-5e26-95471cc33ed9@roeck-us.net>
Date:   Thu, 4 May 2023 07:08:17 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Marco Felsch <m.felsch@...gutronix.de>, andreas@...al.se,
        jun.li@....com, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>
Cc:     linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 3/4] usb: typec: tcpci: clear the fault status bit

On 5/4/23 06:46, Marco Felsch wrote:
> According the "USB Type-C Port Controller Interface Specification v2.0"
> the TCPC sets the fault status register bit-7
> (AllRegistersResetToDefault) once the registers have been reseted to

cleared ? set ?

> their default values.
> 
> This triggers an alert(-irq) on PTN5110 devices albeit we do mask the
> fault-irq. Fix this gernally by writing a one to the correspondig

generically ?

corresponding

> bit-7.
> 
> Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
> ---
>   drivers/usb/typec/tcpm/tcpci.c | 5 +++++
>   include/linux/usb/tcpci.h      | 1 +
>   2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
> index 8da23240afbe..15632d023e4c 100644
> --- a/drivers/usb/typec/tcpm/tcpci.c
> +++ b/drivers/usb/typec/tcpm/tcpci.c
> @@ -602,6 +602,11 @@ static int tcpci_init(struct tcpc_dev *tcpc)
>   	if (time_after(jiffies, timeout))
>   		return -ETIMEDOUT;
>   
> +	regmap_read(tcpci->regmap, TCPC_FAULT_STATUS, &reg);

Needs error check.

Also, I am not sure if this is the correct place for this code. The alert
status is cleared after vendor initialization. Should the same be done
here ? Also, why not just write the bit unconditionally, similar
to TCPC_ALERT ?

Thanks,
Guenter

> +	if (reg & TCPC_FAULT_STATUS_ALL_REG_RST_TO_DEFAULT)
> +		tcpci_write16(tcpci, TCPC_FAULT_STATUS,
> +			      TCPC_FAULT_STATUS_ALL_REG_RST_TO_DEFAULT);
> +
>   	/* Handle vendor init */
>   	if (tcpci->data->init) {
>   		ret = tcpci->data->init(tcpci, tcpci->data);
> diff --git a/include/linux/usb/tcpci.h b/include/linux/usb/tcpci.h
> index 85e95a3251d3..83376473ac76 100644
> --- a/include/linux/usb/tcpci.h
> +++ b/include/linux/usb/tcpci.h
> @@ -103,6 +103,7 @@
>   #define TCPC_POWER_STATUS_SINKING_VBUS	BIT(0)
>   
>   #define TCPC_FAULT_STATUS		0x1f
> +#define TCPC_FAULT_STATUS_ALL_REG_RST_TO_DEFAULT BIT(7)
>   
>   #define TCPC_ALERT_EXTENDED		0x21
>   
>