linux-kernel - Re: [PATCH v2 1/1] usb: typec: tcpci: Clear the fault status register

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Date:   Tue, 07 May 2019 20:49:22 -0600
From:   Angus Ainslie <angus@...ea.ca>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     angus.ainslie@...i.sm,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Guenter Roeck <groeck7@...il.com>
Subject: Re: [PATCH v2 1/1] usb: typec: tcpci: Clear the fault status register

On 2019-05-07 20:03, Guenter Roeck wrote:
> On 5/7/19 5:27 PM, Angus Ainslie (Purism) wrote:
>> If the fault status register doesn't get cleared then
>> the ptn5110 interrupt gets stuck on. As the fault register gets
>> set everytime the ptn5110 powers on the interrupt is always stuck.
>> 
>> Fixes: fault status register stuck
>> Signed-off-by: Angus Ainslie (Purism) <angus@...ea.ca>
>> ---
>>   drivers/usb/typec/tcpm/tcpci.c | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>> 
>> diff --git a/drivers/usb/typec/tcpm/tcpci.c 
>> b/drivers/usb/typec/tcpm/tcpci.c
>> index c1f7073a56de..a5746657b190 100644
>> --- a/drivers/usb/typec/tcpm/tcpci.c
>> +++ b/drivers/usb/typec/tcpm/tcpci.c
>> @@ -463,6 +463,17 @@ irqreturn_t tcpci_irq(struct tcpci *tcpci)
>>   	else if (status & TCPC_ALERT_TX_FAILED)
>>   		tcpm_pd_transmit_complete(tcpci->port, TCPC_TX_FAILED);
>>   +	if (status & TCPC_ALERT_FAULT) {
> 
> Wait - the driver doesn't set TCPC_ALERT_FAULT in the alert mask
> register. How can the chip report it if fault alerts are not enabled ?

Well that I didn't check. But I know this code gets executed so 
something must be turning it on.

Also if I don't clear it I get an unlimited number of interrupts.

> What am I missing here ?

Can the power on fault be masked ?

Angus

> 
> Thanks,
> Guenter
> 
>> +		u16 fault_status;
>> +
>> +		tcpci_read16(tcpci, TCPC_FAULT_STATUS, &fault_status);
>> +
>> +		dev_warn(tcpci->dev, "FAULT ALERT status 0x%x\n", fault_status);
>> +
>> +		/* clear the fault status */
>> +		tcpci_write16(tcpci, TCPC_FAULT_STATUS, fault_status);
>> +	}
>> +
>>   	return IRQ_HANDLED;
>>   }
>>   EXPORT_SYMBOL_GPL(tcpci_irq);
>>