[Gta04-owner] Linux 3.2-rc3 on GTA04

NeilBrown neilb at suse.de
Sat Nov 26 12:43:32 CET 2011

Hi again,

 I have just updated

 to 3.2-rc3.

 Also in this release:

 - Fixed the charging problem - I think [1]
 - We now charge the backup-battery.
 - Brand new driver for the LEDs (tca6507] [2]
 - Backlight control with PWM - untested [3]

 I have had occasional problems with the 'rtc'.  In particular
 hangs and reports that select didn't return.  This can be worked
 around by 
    echo 0 >  /sys/class/rtc/rtc0/wakealarm 
 I sent and email to an upstream developer to get some help.

 1/ There are two component involved in charging.  The 'usb' module
    which lets the power in, and the 'bci' module which does the charging.
    The bci module needs to enable charging after the usb module is active.
    The problem was that the usb module initialises and then runtime power
    management puts it to sleep because it has nothing to do.
    Then the bci module tries to initialise but as the usb module is asleep,
    nothing happens.
    Then when "ifup" loads 'g_ether', the usb modules gets woken up (because
    something wants to use it now) and it initialises, but the bci module
    doesn't get told - at least not until an unplug/replug.

    So I added a callback from usb to bci on wake-from-suspend (that device
    suspend, not full-system suspend) much like the call-back on 'plugged-in'.

    We probably want the bci module to tell the usb module that it should
    stay awake, but I don't know how to do that yet.

    It 'seems' to work, but reading the battery status with via bq27x00
    is still a bit iffy...

 2/ My new from-scratch driver for leds-tca6507 provides full support for
    setting brightness levels and hardware-assisted blinking, all through the
    standard /sys/class/leds/* interface.  The leds are given names:
    (no blue LED - I'm sad :-)

    The driver can also make lines appear as GPIO output.  The Wifi reset now
    appears as /sys/class/gpio/WiFi-Reset
    (I haven't tested it though).

 3/ I included the PWM (Pulse Width Modulation) driver that Nikolaus mentions
    in http://projects.goldelico.com/p/gta04-kernel/issues/85/ and figured
    out how to link it up with the backlight function.

    I've checked that 'setterm -blank force' and 'setterm -blank poke' cause
    the PWM module to request different pulse widths, but I don't know if
    it is actually affecting the backlight (because I don't have one plugged
    Test reports would be most welcome.

    I'm not very happy with the way I had to link in the platform-device
    creation, but it works and maybe isn't so bad after all.

Future plans:
 - I want to look at the accelerometers as the next project.  Part of this is
   understanding the "iio" subsystem which seems to be the appropriate home.
 - I would like to see if I can link the Wifi reset in with the
   'rfkill' infrastructure so the wifi is automagically turned on or off
   based on an rfkill switch.

(and lots more that I'm not even letting myself think about yet).

All input very welcome,


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