Re: [PATCH v3 2/2] usb: typec: tcpci: set ALERT_MASK register after devm_request_threaded_irq()

[Dan Carpenter <dan.carpenter@linaro.org>]

On Tue, Dec 17, 2024 at 05:12:08PM +0800, Xu Yang wrote:
> With edge irq support, the ALERT event may be missed currently. The reason
> is that ALERT_MASK register is written before devm_request_threaded_irq().
> If ALERT event happens in this time gap, it will be missed and ALERT line
> will not recover to high level. However, we don't meet this issue with
> level irq. To avoid the issue, this will set ALERT_MASK register after
> devm_request_threaded_irq() return.
> 
> Fixes: 77e85107a771 ("usb: typec: tcpci: support edge irq")

I agree with Francesco that this was introduced by patch 1 so the
patches need to be folded together into one patch.  The commit
message would be something like:

    The ordering of setting up the IRQs is not correct here.
    We need to call tcpci_register_port() devm_request_threaded_irq().
    Otherwise if we recieve an IRQ before tcpci_register_port() has
    completed it leads to a NULL dereference in tcpci_irq() because
    tcpci->regmap and other pointers are NULL.

    However, moving tcpci_register_port() earlier creates a problem
    of its own because there is a potential that tcpci_init() will be
    called before devm_request_threaded_irq().  The tcpci_init()
    writes the ALERT_MASK to the hardware to tell it to start
    generating interrupts but we're not ready to deal with them yet.

    Move the ALERT_MASK stuff until after the call to
    devm_request_threaded_irq() has finished.

Something like that.

regards,
dan carpenter