[Gta04-owner] Further 3.17 kernel development for GTA04

[Dr. H. Nikolaus Schaller]

Hi Neil,

Am 03.11.2014 um 08:36 schrieb Dr. H. Nikolaus Schaller <hns at goldelico.com>:

> 
> Am 03.11.2014 um 08:27 schrieb NeilBrown <neilb at suse.de>:
> 
>> On Mon, 3 Nov 2014 07:57:00 +0100 "Dr. H. Nikolaus Schaller"
>> <hns at goldelico.com> wrote:
>> 
>>> 
>>> 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.
>>> 
>>> http://projects.goldelico.com/p/gta04-kernel/issues/587/
>>> 
>>> And, I had to disable something because I got kernel panics.
>>> 
>>> Which sound system did you use? ti,omap-twl4030 or goldelico,gta04-audio?
>> 
>> I don't have the goldelico one at all.  Just ti,omap-twl4030 with some
>> modification to support an external device connected to the voice port.
>> 
>> 
>>> 
>>> 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…
>> 
>> Can't explain that.  Both my A3 and A4 boards work.
>> Maybe watch ‘grep hdq /proc/interrupts' and see if it changes at all.
> 
> It says :
> 
> 235:         22      INTC  58  omap_hdq
> 
> and does not change if I try to cat /sys/class/power_supply/bq27000-battery/voltage_now
> 
> So indeed someone is blocking these interrupts. Now I have to identify that “someone” first,
> but it is easier with a good test case.

Looks as if I have found it, although I have really no explanation.

It appears to be related to the DTR patch to omap-serial.c that we have (I think inherited from
kernel 3.7) to control the virtual GPIO of the w2sg driver. If I checkout the latest from linus/3.18-rc2, hdq works.

Of course GPS does not work any more, because the DTR control is then missing.

It appears to be sufficient to add/remove that patch (which is not in mainline Linux - just in
our 3.18-rc2 and therefore you have no chance to see this effect) to start/stop HDQ interrupts.

I will report if I get a better understanding why this DTR code can interfere with HDQ and
which line(s) of code makes the difference.

BR,
Nikolaus