Re: [PATCH v4 1/2] tty: serial: qcom_geni_serial: IRQ cleanup

[Akash Asthana <akashast@codeaurora.org>]

On 11/6/2019 10:03 PM, Stephen Boyd wrote:
Thanks for reviewing.
> Quoting Greg KH (2019-11-06 04:16:00)
>> On Tue, Nov 05, 2019 at 05:00:12PM -0800, Stephen Boyd wrote:
>>> Quoting Greg KH (2019-11-05 09:17:05)
>>>> On Tue, Nov 05, 2019 at 03:27:15PM +0530, Akash Asthana wrote:
>>>>> @@ -1307,7 +1307,21 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
>>>>>        port->handle_rx = console ? handle_rx_console : handle_rx_uart;
>>>>>        if (!console)
>>>>>                device_create_file(uport->dev, &dev_attr_loopback);
>>>>> -     return uart_add_one_port(drv, uport);
>>>>> +
>>>>> +     ret = uart_add_one_port(drv, uport);
>>>>> +     if (ret)
>>>>> +             return ret;
>>>> What is going to remove the sysfs file you just created above (in a racy
>>>> way, it's broken and needs to be fixed, but that's a different issue
>>>> here...)?
>>>>
>>>>
>>>>> +
>>>>> +     irq_set_status_flags(uport->irq, IRQ_NOAUTOEN);
>>>>> +     ret = devm_request_irq(uport->dev, uport->irq, qcom_geni_serial_isr,
>>>>> +                     IRQF_TRIGGER_HIGH, port->name, uport);
>>>>> +     if (ret) {
>>>>> +             dev_err(uport->dev, "Failed to get IRQ ret %d\n", ret);
>>>>> +             uart_remove_one_port(drv, uport);
>>>>> +             return ret;
>>>> Does this remove the sysfs file?
>>>>
>>> The loopback file isn't documented. It isn't removed when the driver is
>>> removed either. Can we just remove the whole thing? It would be nicer if
>>> that sort of thing was supported in the tty layer somehow. Is it?
>> I don't know what that file does, so yes, please delete it :)

This sysfs file was exposed to user to configure hardware to run in 
loopback mode (sorting TX and RX lines).

We use this mode to sanity test TX and RX path of the driver after 
making any code changes.

But we can remove this sysfs file and use TIOCM_LOOP to set HW in 
loopback mode as suggested by stephen.

>> And as for support in the tty layer itself, if you figure out what it
>> does, sure, we can add support if needed.
>>
> I think it may be supported in the tty layer with TIOCM_LOOP already.
> Akash, can you confirm?

Yeah, its already supported in tty layer. We can call TIOCMSET ioctl 
from user space test application with TIOCM_LOOP argument to configure 
our HW in loopback mode.

I will remove all the code related to loopback sysfs.

Thanks for this suggestion.

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