[Gta04-owner] Further 3.17 kernel development for GTA04

[NeilBrown]

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.

NeilBrown
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