[Gta04-owner] Further 3.17 kernel development for GTA04

Dr. H. Nikolaus Schaller hns at goldelico.com
Mon Nov 3 07:57:00 CET 2014

Am 03.11.2014 um 07:44 schrieb NeilBrown <neilb at suse.de>:

> On Mon, 3 Nov 2014 07:00:42 +0100 "Dr. H. Nikolaus Schaller"
> <hns at goldelico.com> wrote:
>> Hi,
>> Am 02.11.2014 um 10:51 schrieb NeilBrown <neilb at suse.de>:
>>> I've made some useful progress.
>>> Nearly all the things that I need regularly work.  So I can make phone calls
>>> (on the GTA04a4, not on the a3),
>> ah, did you solve the ALSA sound driver issues?
> What ALSA sound driver issues?

Proper device tree based Tri-State control for McBSP to switch between hardware and
software routing.


And, I had to disable something because I got kernel panics.

Which sound system did you use? ti,omap-twl4030 or goldelico,gta04-audio?

The first one should work out of the box and the second one fails.

>>> use the wifi, charge the battery and
>>> monitor its status, and turn the GPS on/off using my new approach.  There is
>>> no-longer an ‘rfkill' for GPS - opening /dev/ttyO1 does all that is needed.
>> Hm. I am not happy that there is no rfkill. Well, someone commented that
>> GPS is not a transmitter, but Linux provides the rfkill gps switch (and we have
>> not introduced it). And, basically the antenna amplifier might transmit (if it runs
>> out of control) so it is safer in an airplane situation to be able to turn off the
>> LNA power explicitly. But keep gpsd and tangogps running. A user might
>> be just looking into local maps.
> It can be added back if it is really needed.
> It always thought it was a bit odd as rfkill is, like you say, primarily
> about transmitters.
> I'd like to know if anyone else is using a 'gps' rfkill  ... I couldn't find
> any documentation or useful references last time I looked.

I don’t know either, but that nobody might have to solve the same problem
as we have to solve.

>>> I'm not entirely happy with this code yet but it is quite usable.
>>> Suspend seems to work reliably, but power usage is way too high - about
>>> 50mA.  There are hints in some patches in 3.18-rc, so USB might be to blame
>>> for some of that extra usage, so I'll probably be looking that that when I
>>> next get some time.
>>> My kernel doesn't currently "export" the various GPIOs that need to be
>>> manually poked.
>>> I have this code:
>>> for l in 186,high 175,high 23,low 21,high
>>> do
>>>    g=${l%,*}
>>>    echo $g > /sys/class/gpio/export
>>>    echo ${l#*,} > /sys/class/gpio/gpio$g/direction
>>> done
>>> in an init.d script which sets some of these up.  GPIO186 is particularly
>>> needed for turning the GSM modem on.
>> What are these gpios good for? The modem should be controlled through
>> rfkill wwan. For this we have prepared a special driver in the gta04-kernel that
>> pulses the modem gpio in a similar way as for GPS (there is no UART we can
>> use to auto-control modem power).
> A driver which I obviously don't have.  I'll try to look at it when I get a
> chance.
> My user-space code wants to poke the gpio, so I provided it.
> The others I just provided to I could be certain they were in the correct
> position for low power usage.
>>> I've re-organised my tree as a set of topic branch, mostly based on
>>> v3.17, though the 'dts' branch with device-tree changes is based on
>>> git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap
>>>  tag omap-for-v3.17/dt-gta04
>>> which has some gta04 stuff that didn't quite make 3.17 - is in 3.18-rc1
>>> The branches are:
>>> 'dts', 'hdq', 'dss', 'pwm-old', 'input', 'hacks', 'wifi', 'extcon', 'itg',
>>> ‘tty-slave', 'audio', 'twl4030' and 'charger'
>> the hdq patch (there is a missing/wrong compatible entry in the driver) 
>> appears to be the last missing piece we have to make it working .
>> Does it work for you? I see it start up and read the bq27000 several times,
>> but ca. 4.5 seconds after kernel startup it stops. I suspect some IRQ
>> interference (maybe from a subsystem that you do not have).
> It works very reliably for me.
> The behaviour you describe is vaguely reminiscent of problems I was having
> ages ago which were due to runtime PM issues with the hdq driver.  I think
> the fixes went upstream, possibly
> commit c354a86484b61e32100eb94c1f3f0aa512958cee
> Looking at my mail records, the issue was fixed in 3.6.
> There was one time recently when reads from one of the sysfs bq27000 files started
> returning ENXIO (or maybe ENODEV), but it hasn't happened again.  I'll keep an eye
> out for problems.

It is indeed strange. I have added some printk to report hdq write&read and timeouts:

[    3.894470] omapfb omapfb: no displays
[    3.899444] omapfb omapfb: failed to setup omapfb
[    3.904449] platform omapfb: Driver omapfb requests probe deferral
[    3.912017] platform 4806a000.serial: Driver omap_uart requests probe deferral
[    3.920532] platform 4806c000.serial: Driver omap_uart requests probe deferral
[    3.929016] platform 480b4000.mmc: Driver omap_hsmmc requests probe deferral
[    3.938201] ALSA device list:
[    3.941314]   No soundcards found.
[    3.947357] hdq_write_byte(00000027) ok
[    3.951568] hdq_read_byte -> 00
[    4.148071] hdq_write_byte timeout
[    4.350708] hdq_read_byte timeout
[    4.548431] hdq_write_byte timeout
[    4.748565] hdq_read_byte timeout
[    4.948394] hdq_write_byte timeout

I suspect some other subsystem might be influencing interrupts.

Something to locate by disabling one driver after the other…


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