[Gta04-owner] Further 3.17 kernel development for GTA04

NeilBrown neilb at suse.de
Tue Nov 4 22:41:50 CET 2014


On Tue, 4 Nov 2014 21:13:02 +0100 "Dr. H. Nikolaus Schaller"
<hns at goldelico.com> wrote:

> Hi Neil,
> 
> Am 04.11.2014 um 20:55 schrieb NeilBrown <neilb at suse.de>:
> 
> > On Tue, 4 Nov 2014 06:54:33 +0100 "Dr. H. Nikolaus Schaller"
> > <hns at goldelico.com> wrote:
> > 
> >> 
> >> Am 03.11.2014 um 22:50 schrieb NeilBrown <neilb at suse.de>:
> >> 
> >>> On Mon, 3 Nov 2014 22:25:46 +0100 "Dr. H. Nikolaus Schaller"
> >>> <hns at goldelico.com> wrote:
> >>> 
> >>>> Hi again,
> >>>> 
> >>>> Am 03.11.2014 um 20:04 schrieb Dr. H. Nikolaus Schaller <hns at goldelico.com>:
> >>>> 
> >>>>> Hi Neil,
> >>>>> 
> >>>>> Am 03.11.2014 um 14:44 schrieb Dr. H. Nikolaus Schaller <hns at goldelico.com>:
> >>>>> 
> >>>>>> 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.
> >>>>> 
> >>>>> After a lot of trial and error, I still don’t understand it. But it appears to have something to do
> >>>>> with the UART3 + console handling. There is one line in the driver where the DTR gpio is derived
> >>>>> from the device tree.
> >>>>> 
> >>>>> If I keep it as is (it reads the “dtr-gpio” property from the DT), we have serial and GPS, but the hdq hangup.
> >>>>> If I force this gpio to 0, hdq works, but the console output goes to the LCD (I have never seen that before), and we have no GPS.
> >>>>> If I force it to -ENOENT (which is equivalent to a DT definition with missing dtr-gpio specification), we have serial and hdq, but no GPS.
> >>>>> If I force it to -EPROBE_DEFER, console goes to LCD. There is no GPS, hdq does not work.
> >>>>> 
> >>>>> Now, I guess our DTR patch interferes with the takeover of UART3 by this driver. Or alternatively,
> >>>>> that deferred probing in omap_serial has some side-effect for UART0 or UART1.
> >>>> 
> >>>> after some more tests I am quite sure that the problem is deferred probing of uart drivers.
> >>>> 
> >>>> If I disable the return -EPROBE_DEFER paths [2] in serial_omap_probe() hdq works (and GPS fails).
> >>>> If I enable them, hdq fails and GPS works (if configured).
> >>> 
> >>> Based on that evidence, it could be that the GPS interferes with HDQ.
> >> 
> >> it is definitively not the GPS driver. I can disable it from .config and hdq still breaks. It is
> >> sufficient to have it in the DT.
> >> 
> >> The only condition is that the dtr-gpio defined for the UART does not successfully probe
> >> immediately.
> >> 
> > 
> > I decided to try your kernel
> > Specifically, commit 16243938d0438c872c1da06183af726631402f24 from
> > goldelico/work/hns/3.18-hdq, with
> 
> Yes, in the hdq branch hdq battery works - but without GPS. If GPS is configured/added
> hdq fails.
> 
> But I think I have not commited such a state.
> 
> In 3.18-rc2 hdq fails - but because it is not properly configured.
> 
> > 
> >    { .compatible = "ti,omap-hdq", },
> > 
> > 
> > changed to 
> > 
> >    { .compatible = "ti,omap3-1w", },
> > 
> > and the HDQ deivce sees to work perfectly.  Maybe there are differences
> > in .config…
> 
> > 
> > If you would like to give me your .config
> 
> the defconfig used is arch/arm/configs/gta04_defconfig
> 
> > and a git commit number that is
> > failing for you, I’ll see if I can reproduce it.
> 
> I was not fast enough to announce that it now appears to work.
> 
> What I have done:
> cherry-pick the relevant patches from the 3.18-hdq branch
> merge 3.18-rc3
> 
> And it simply works. The hdq interrupt hickup has gone.
> 
> I have two potential reasons but it is probably not worth to deeper analyse:
> * it might be something was wrong in 3.18-rc1 and rc2 which was fixed now
> * adding printk into drivers that are probed while UART3 is itself being probed might lead to this type of hangup
> 
> So the 3.18-rc3 works (I have tested on two boards). Both,
> 
> cat /sys/class/power_supply/bq27000-battery/uevent
> 
> and 
> 
> cat /dev/ttyO1
> 
> work as expected.
> 
> Thanks for encouraging to continue to dig into this issue.

Good news!  Thanks.

NeilBrown

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