poll_once=off not needed?!

[r00t-]

while debugging my hardware (still not working :\ ),
i found this great document (you might want to add a link to the documentation):
https://community.silabs.com/s/article/linux-sdio-detection?language=en_US

it tells us:

Checking the mmc bus commands during the SDIO detection phase [...] is the trickiest part,
since it involves tracking message normally issued at boot, when the system is attempting SDIO detection.
In reality, these are issued every time the mmc bus is bound to the system,
so unbinding/binding the mmc bus will trigger a new detection attempt.

echo 3f300000.mmc > /sys/bus/platform/drivers/mmc-bcm2835/unbind 2>/dev/null
sleep 2
echo 3f300000.mmc > /sys/bus/platform/drivers/mmc-bcm2835/bind

(the id is not the same on my raspberry pi, but it can be found with ls /sys/bus/platform/drivers/mmc-bcm2835/)

it's neat how with poll_once=off i can see the system regularly polling the sdio bus - i see pulses on the clock line with my 'scope,
but i can also see them with poll_once on, at boot and when re-binding the driver.

(i am somewhat unsure if undbinding the driver might break communication with the sd card? but i'm not seeing issues.)
also not sure if this can be triggered from inside the driver, where the reset is currently implemented - but maybe it's not needed anymore if it can be done from userspace like this, might also help make it easier to just remove that code to solve #57 .