On Fri, May 21, 2021 at 06:08:43AM +0000, Zheyu Ma wrote:

In 'rp2_probe', the driver registers 'rp2_uart_interrupt' then calls
'rp2_fw_cb' through 'request_firmware_nowait'. In 'rp2_fw_cb', if the
firmware don't exists, function just return without initializing ports
of 'rp2_card'. But now the interrupt handler function has been
registered, and when an interrupt comes, 'rp2_uart_interrupt' may access
those ports then causing NULL pointer dereference or other bugs.

Because the driver does some initialization work in 'rp2_fw_cb', in
order to make the driver ready to handle interrupts, 'request_firmware'
should be used instead of asynchronous 'request_firmware_nowait'.

You just now slowed down the probe function.  Are you _sure_ this is ok?

Do you have this hardware to test this?  If so, what is the init time
before and after this change?

thanks,

greg k-h