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FS#11149 - Possible alternative fix for ipod shutdown/reboot issue

Attached to Project: Rockbox
Opened by Torne Wuff (torne) - Sunday, 28 March 2010, 23:41 GMT+2
Last edited by Torne Wuff (torne) - Sunday, 05 June 2011, 13:02 GMT+2
Task Type Patches
Category Operating System/Drivers
Status Closed
Assigned To Torne Wuff (torne)
Player Type iPod 5G
Severity Medium
Priority Normal
Reported Version Daily build (which?)
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Private No

Details

The current workaround for the iPod startup issue (from  FS#10107 ) is rather unsatisfactory - it has the cosmetic issue of the power icon on shutdown, and it seems to cause alarm wakeups for some people (possibly specific models/OF versions).

As a possible alternative, I am testing simply clearing the relevant portion of IRAM on shutdown, in the hope that this will cause the iPod to always assume it is booting in the normal way as if it were a hard reset. So far this has worked fine on my iPod Video 80GB, but it needs much more thorough testing on a variety of models. This is just a hunch, incidentally, I have not completed enough of a disassembly of the boot rom to work out why the original problem occurs.

The attached patch reverts the change from  FS#10107 , and makes the IRAM clearing change instead.

If you test this and you still get the original boot problem, even once, please reply ASAP with the model and original firmware version.
   ipod-alternative-shutdown-fix.diff (2.3 KiB) 
 firmware/target/arm/ipod/power-ipod.c |   28 ++++++++--------------------
 manual/rockbox_interface/main.tex     |    6 ------
 2 files changed, 8 insertions(+), 26 deletions(-)

This task depends upon

Closed by  Torne Wuff (torne)
Sunday, 05 June 2011, 13:02 GMT+2
Reason for closing:  Fixed
Additional comments about closing:  This is as good as we're going to get unless someone manages to work out what the root cause of the original problem is. The problem is fixed for some people/models and greatly reduced in frequency for most.
Comment by Torne Wuff (torne) - Friday, 02 April 2010, 15:58 GMT+2
Test builds for this change are available at http://forums.rockbox.org/index.php?topic=24376.0
Comment by Torne Wuff (torne) - Monday, 24 May 2010, 13:08 GMT+2
This has been committed, however some people's players still need to be reset. It fixes it completely for many people, though...

For now I'm leaving this fix in, since it doesn't have the unpleasant side effects of  FS#10107 , but we should see what else we can come up with.
Comment by Boris Gjenero (dreamlayers) - Thursday, 22 July 2010, 03:52 GMT+2
This leads me to hypothesize that the problem occurred due to IRAM retaining some data while unpowered. This phenomenon has been documented, especially relating to http://en.wikipedia.org/wiki/Cold_boot_attack . That would explain why the problem seemed to occur more often when my iPod was cold or when I tried to turn it on soon after turning it off. Although the cold boot attack was normally done with DRAM, SRAM (such as the PP502X IRAM) is also vulnerable.
Comment by Torne Wuff (torne) - Thursday, 22 July 2010, 11:34 GMT+2
This doesn't fix it for a lot of people, though, it seems.. so I suspect something more complicated is going on.
Comment by Marcin Bukat (MarcinBukat) - Tuesday, 14 September 2010, 12:12 GMT+2
I just hit the issue on my mini 1G with quite recent build (~ week old or something like this). I haven't seent this behaviour for ages.
Comment by John (jmf) - Thursday, 13 January 2011, 18:18 GMT+2
I stumbled on this looking for info on the problem I'm having. My 5.5g will often not shutdown. The top run time is something like 520 hours. I'll often get the "shutting down" screen, but will then come back to the player later and find it playing. I'll also "shut down" the player at night only to find it dead in the morning.

On another note, dead isn't always dead. Sometimes I'll try to boot and get some variety of a low battery error, but will eventually get the player to boot and the batt will eventually stabalize at 50+%.

I have no coding background with rockbox, and therefore have no idea why any of this would happen. Just throwing it out there.
Comment by Boris Gjenero (dreamlayers) - Thursday, 13 January 2011, 18:27 GMT+2
John, does your iPod turn on immediately after shutting down or at some later time? If it turns on immediately, that might be due to defective USB power circuitry. I wrote about the issue on my blog at http://dreamlayers.blogspot.com/2008/12/video-ipod-wont-charge-via-usb-wont.html . If it turns on later, that could just be an alarm.

It's usually a bad idea to ignore Rockbox low battery errors and keep turning on the device until it stays on. That could excessively discharge the battery. Low temperatures can cause low battery errors even when the battery has plenty of charge left. Even in such cases, warming up the device is much better than continually attempting to turn it on.
Comment by John (jmf) - Thursday, 13 January 2011, 23:02 GMT+2
I stumbled on this looking for info on the problem I'm having. My 5.5g will often not shutdown. The top run time is something like 520 hours. I'll often get the "shutting down" screen, but will then come back to the player later and find it playing. I'll also "shut down" the player at night only to find it dead in the morning.

On another note, dead isn't always dead. Sometimes I'll try to boot and get some variety of a low battery error, but will eventually get the player to boot and the batt will eventually stabalize at 50+%.

I have no coding background with rockbox, and therefore have no idea why any of this would happen. Just throwing it out there.
Comment by John (jmf) - Thursday, 13 January 2011, 23:03 GMT+2
Sorry for the dupe post there... My ipod turns on again after a while. It does not immediately reboot.
Comment by John (jmf) - Thursday, 13 January 2011, 23:08 GMT+2
Re: the low battery.. I did notice that the ipod is sensitive to cold. Since then it has spent every night inside. I thought that had completely addressed the issue but the other morning I went to start it up and got the low battery shutdown. I figured the player had started again and run out the battery, but incredibly, when I rebooted it, the battery stabilized at 53%!

One other detail comes to mind with the auto-start - sometimes when the player autostarts, it will run out the battery and get into a loop where it will hang at the shutdown screen and then reset, thereby rebooting and eventually hanging again. That continues until eventually I get "cannot divide by zero".

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