[Letux-kernel] gta04a5 + bluetooth + letux 4.19.0.3 = mysterious things ahead

Andreas Kemnade andreas at kemnade.info
Mon Nov 5 07:38:15 CET 2018


Hi,

On Sun, 4 Nov 2018 19:40:48 +0100
"H. Nikolaus Schaller" <hns at goldelico.com> wrote:

> > Am 04.11.2018 um 15:18 schrieb Andreas Kemnade <andreas at kemnade.info>:
> > 
> > Hi,
> > 
> > I am wondering about bluetooth behavior on a5:
> > 
> > - Suspend current decrease by 6mA (I have seen 12mA suspend without
> >  modem): my doing the following steps
> >   1. booting without bluetoothd, module autoloading, no uart idling
> >   2. hciconfig hci0 up (it is still down)
> >   3. rmmod hci_uart
> >   4. suspend
> > 
> >  To clarify 6mA lower than without modules.
> >
I am wondering what happens here. This sequence changes something.
But what?
-External pin state
 - CTS/RTS / PCM pins?
-Internal state of the module (but it should be..off anyways)
-Internal state of the soc
-energy harvesting functionality of the bt/wifi combo module ;-)

But then the interesting question is why I see this only on runtime.
 
> > - wlan screws up when hci_uart is removed and a certain set of things
> >  is idled. I have not fully evaluated this.
> >  Required:
> >    allowing bluetooth uart to suspend
> >  echo 3000  
> >> /sys/bus/platform/drivers/omap_uart/4806a000.serial/power/autosuspend_delay_ms  
> >  Definitively not required:
> >    allowing gps uart to suspend, gps can be active. Their modules
> >    clocks depend on the same clocks.
> > 
> >  sdcard access still works.
> >  To recover wifi you have to unbind and rebind omap_hsmmc via sysfs.  
> 
> Hm. Maybe they share some clock?
> 
Or maybe the module gets confused because of some RTS/CTS/whatever
state. UART1/UART2 clocks have common parents,
MMC1/2 should also have. So I would expect trouble when both
UART1/2 are powered down. But not only one.

Regards,
Andreas
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