Hi Peter,
On 07/11/2013 10:00 PM, Peter Barada wrote:
On 07/09/2013 11:55 AM, Tony Lindgren wrote:
* Peter Barada <peter.barada@xxxxxxxxxxx> [130709 08:14]:
I'm working with a 3.0.8 kernel in Android ICS and have run into a
problem using wl12xx bluetooth after a suspend/resume cycle.
GPIO_162 in this design is connected to the BT_EN pin of the wl12xx and
needs to be held high to keep the bluetooth core from resetting while
the DM37x goes into off mode.
I've tried muxing the pin using OMAP_PIN_OUTPUT |
OMAP_PIN_OFF_OUTPUT_HIGH, but the pin goes low when the chip goes into
off mode. If I disable off mode via "echo 0 >
/sys/kernel/debug/pm_debug/enable_off_mode" the pin remains high while
the chip goes into retention and the bluetooth core works after resume.
Any ideas why GPIO_162 would go low during suspend to off mode?
Unless the GPIO is in a GPIO bank that's connected to the WKUP
power domain, the GPIO bank context will be lost. So there's a short
period where the GPIO bank is in an uninitialized state between waking
from off-idle and before the context to the GPIO bank gets restored in
omap_gpio_runtime_resume().
If there's a pull on the line, the period is long enough to change
the line.
Unless the TI people know some magic tricks that I'm not aware of,
there's no way around it, except to use external pulls to keep
the GPIO line in desired state, or move the GPIO somewhere else,
like TWL.
Unfortunately the hardware doesn't have an external pullup, and
re-spinning it to route BT_EN to a GPIO pin that's in the WKUP domain
isn't an option at this time...
Unless there's some TI-magic to keep GPIO_162 high during OFF mode I'll
have to solve this the hard way by reinitializing the BT/GPS core during
resume using deferred work. Unfirtuantely I don't have a clear
understanding of the userspace interaction to know if this is doable.
Mechanically it doesn't look too difficult to use the guts of
st_register/st_kim_start to reinitialize the GT/GPS core and download
its firmware, but the userspace interactions (and the time it takes to
load the firmware) is what makes coming up with a good solution difficult.
Any suggestions on how to approach solving this are most appreciated!
The recommended way is to configure it as INPUT + PULL_UP
and don't use OFFMODE feature if the 1 value is needed on port during
off-mode.
You need to check if you have valid pin-cfg right before call to
omap4_enter_lowpower() ->omap4_cpu_suspend(cpu, save_state);
I recommend you to ask you questions here:
http://e2e.ti.com/support/omap/default.aspx
Regards,
- grygorii
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