[Gta04-owner] Detecting USB cable insert

[NeilBrown]

On Mon, 21 Nov 2011 15:50:46 +0100 "Dr. H. Nikolaus Schaller"
<hns at goldelico.com> wrote:

> Hi,
> 
> Am 21.11.2011 um 14:22 schrieb Radek Polak:
> 
> > Hi,
> > on GTA02 there were comming messages on netlink when USB connector was plugged  
> 
> This one: http://en.wikipedia.org/wiki/Netlink ?
> 
> > and also for battery charge changes. I havent noticed any netlink messages on 
> > GTA04. Is there any recommended way how to detect USB cable plugging and 
> 
> I have not seen any netlink code in the BeagleBoard based kernels. So it must
> have been something special for the GTA02.
> 
> > battery charging events?
> 
> I am not sure if there are any events (except some dmesg) associated.
> 
> The status can be polled through /sys. One is the twl4030_bci
> (battery charger). The other should be the "musb" (Mentor USB) driver which
> controls the USB/OTG part.
> 
> If we implement some new notification schemes we should look what
> Kernel 3.2, Nokia N900, OpenPandora and other TI OMAP based devices
> are doing.
> 

I think the "correct" way to get power change notifications is as udev events.

So on my 3.2-rc kernel when I plug in USB while running 
   udevadm monitor --kernel

I see

KERNEL[946688178.944335] change   /devices/platform/omap/musb-omap2430/musb-hdrc/udc/musb-hdrc (udc)
KERNEL[946688178.950195] change   /devices/platform/omap/omap_i2c.1/i2c-1/1-004b/twl4030_bci/power_supply/twl4030_ac (power_supply)
KERNEL[946688178.952423] change   /devices/platform/omap/omap_i2c.1/i2c-1/1-004b/twl4030_bci/power_supply/twl4030_usb  (power_supply)

The twl4030_bci_battery drive in the hardware-validation kernel has a call
to power_supply_changed() which is what leads to these (I think) so I suspect
it would have the same sort of messages.

I think these come out through dbus too.

NeilBrown

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