Re: [linux-sunxi] Kernel damaged device?

[Leonardo]

Em domingo, 21 de agosto de 2016 09:16:09 UTC-3, Luc Verhaegen escreveu:
>
> On Sat, Aug 20, 2016 at 07:26:46PM -0700, Leonardo wrote: 
> > Hi. I'm building a very minimal Linux distro to use as an embedded 
> system 
> > on a A20 tablet. I don't want to believe this, but I think that booting 
> my 
> > distro has damaged the device. The tablet came with Android. I had it 
> > rooted so I could extract the fex file. Then I got kernel 3.4.104 and 
> uboot 
> > 2016.02 from GitHub, built my file system with buildroot and so on. I'm 
> > using an SD card for now. So I tried booting my system and nothing came 
> up 
> > on the LCD. Then I remove my SD card, try to get back to Android and 
> still 
> > nothing on the screen! The device is not dead. I can access it using ssh 
> > over the wifi, the usb port works fine. Basically I can do anything 
> > remotely. At first I thought I might have damaged something on the PCB 
> > while performing the tests, so I had a second tablet. Boot on Android, 
> > display works fine. Boot on my distro, nothing on screen. Try to get 
> back 
> > to Android, and nothing on the screen again. By the way, the backlight 
> > lights up as usual, so the display is not dead also. I've worked on a 
> > similar project last year and had no problem like this at all. I have no 
> > idea what went wrong. Is it possible that my kernel has damaged the 
> device 
> > somehow? 
>
> Damage, no. Ruined nand content due to different settings, yes. 
>
> Thank allwinner for changing its mind on how to configure its nand 
> controller in the middle of the A20 lifetime, while having code in 
> its nand driver that clears the ram if it finds garbage. 
>
> Luc Verhaegen. 
>

That makes sense. I tried dumping /dev/nand and got 8GB of 0xFF. In 
addition to that, there's this message on boot:

[NAND] nand driver version: 0x2 0x9
Dev Sunxi softw311 nand magic does not match for MBR 1: 
...
Dev Sunxi softw311 nand header bad for all MBR copies, MBR corrupted or not 
present.
 nand: unknown partition table
[NAND]nand driver, ok.

Last year I had this embedded system running on a 7" tablet. Now I'm trying 
the same using a 9" one. Both are A20 and from the same manufacturer. 
Actually the designs are quite similar, except for the screen size and some 
small changes on the PCB. So I got the system I'm currently setting up, 
changed its fex for the 7" one and gave it a try
on the smaller tablet. I got everything on screen by the first run... Back 
to the 9" tablet, after changing back the fex file, and blank screen 
again... I was thinking before that I could have stripped down my kernel 
too much, and because of that the screen wasn't working, but now I don't 
know what to think... 

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Re: [linux-sunxi] Kernel damaged device?

[Leonardo]

2016-08-21 9:20 GMT-03:00 Luc Verhaegen :
>
> On Sat, Aug 20, 2016 at 07:26:46PM -0700, Leonardo wrote:
> > Hi. I'm building a very minimal Linux distro to use as an embedded system
> > on a A20 tablet. I don't want to believe this, but I think that booting my
> > distro has damaged the device. The tablet came with Android. I had it
> > rooted so I could extract the fex file. Then I got kernel 3.4.104 and uboot
> > 2016.02 from GitHub, built my file system with buildroot and so on. I'm
> > using an SD card for now. So I tried booting my system and nothing came up
> > on the LCD. Then I remove my SD card, try to get back to Android and still
> > nothing on the screen! The device is not dead. I can access it using ssh
> > over the wifi, the usb port works fine. Basically I can do anything
> > remotely. At first I thought I might have damaged something on the PCB
> > while performing the tests, so I had a second tablet. Boot on Android,
> > display works fine. Boot on my distro, nothing on screen. Try to get back
> > to Android, and nothing on the screen again. By the way, the backlight
> > lights up as usual, so the display is not dead also. I've worked on a
> > similar project last year and had no problem like this at all. I have no
> > idea what went wrong. Is it possible that my kernel has damaged the device
> > somehow?
>
> Damage, no. Ruined nand content due to different settings, yes.
>
> Thank allwinner for changing its mind on how to configure its nand
> controller in the middle of the A20 lifetime, while having code in
> its nand driver that clears the ram if it finds garbage.
>
> Luc Verhaegen.

That makes sense. I tried dumping /dev/nand and got 8GB of 0xFF. In
addition to that, there's this message on boot:

[NAND] nand driver version: 0x2 0x9
Dev Sunxi softw311 nand magic does not match for MBR 1: 
...
Dev Sunxi softw311 nand header bad for all MBR copies, MBR corrupted
or not present.
 nand: unknown partition table
[NAND]nand driver, ok.

Last year I had this embedded system running on a 7" tablet. Now I'm
trying the same using a 9" one. Both are A20 and from the same
manufacturer. Actually the designs are quite similar, except for the
screen size and some small changes on the PCB. So I got the system I'm
currently setting up, changed its fex for the 7" one and gave it a try
on the smaller tablet. I got everything on screen by the first run...
Back to the 9" tablet, after changing back the fex file, and blank
screen again... I was thinking before that I could have stripped down
my kernel too much, and because of that the screen wasn't working, but
now I don't know what to think...

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Re: [linux-sunxi] Kernel damaged device?

[Leonardo]

Hi. I'm using the fex I've extracted from its nand.

2016-08-21 2:05 GMT-03:00 Alexsey Shestacov :

> Noway, kernel it self cant do that, do you.unsing same *.fex file that
> before?
>
> воскресенье, 21 августа 2016 г. пользователь Leonardo написал:
>
>> Hi. I'm building a very minimal Linux distro to use as an embedded system
>> on a A20 tablet. I don't want to believe this, but I think that booting my
>> distro has damaged the device. The tablet came with Android. I had it
>> rooted so I could extract the fex file. Then I got kernel 3.4.104 and uboot
>> 2016.02 from GitHub, built my file system with buildroot and so on. I'm
>> using an SD card for now. So I tried booting my system and nothing came up
>> on the LCD. Then I remove my SD card, try to get back to Android and still
>> nothing on the screen! The device is not dead. I can access it using ssh
>> over the wifi, the usb port works fine. Basically I can do anything
>> remotely. At first I thought I might have damaged something on the PCB
>> while performing the tests, so I had a second tablet. Boot on Android,
>> display works fine. Boot on my distro, nothing on screen. Try to get back
>> to Android, and nothing on the screen again. By the way, the backlight
>> lights up as usual, so the display is not dead also. I've worked on a
>> similar project last year and had no problem like this at all. I have no
>> idea what went wrong. Is it possible that my kernel has damaged the device
>> somehow?
>>
>>

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Re: [linux-sunxi] Kernel damaged device?

[Leonardo]

2016-08-21 6:58 GMT-03:00 Hans de Goede :

> Hi,
>
> On 21-08-16 04:26, Leonardo wrote:
>
>> Hi. I'm building a very minimal Linux distro to use as an embedded system
>> on a A20 tablet. I don't want to believe this, but I think that booting my
>> distro has damaged the device. The tablet came with Android. I had it
>> rooted so I could extract the fex file. Then I got kernel 3.4.104 and uboot
>> 2016.02 from GitHub, built my file system with buildroot and so on. I'm
>> using an SD card for now. So I tried booting my system and nothing came up
>> on the LCD. Then I remove my SD card, try to get back to Android and still
>> nothing on the screen! The device is not dead. I can access it using ssh
>> over the
>> wifi, the usb port works fine. Basically I can do anything remotely. At
>> first I thought I might have damaged something on the PCB while performing
>> the tests, so I had a second tablet. Boot on Android, display works fine.
>> Boot on my distro, nothing on screen. Try to get back to Android, and
>> nothing on the screen again. By the way, the backlight lights up as usual,
>> so the display is not dead also. I've worked on a similar project last year
>> and had no problem like this at all. I have no idea what went wrong. Is it
>> possible that my kernel has damaged the device somehow?
>>
>
> Try removing all power from the device to really get it in a clean hw
> state. You can force shutdown
> the device by keeping the power button pressed for 12+ seconds.
>
> Regards,
>
> Hans
>

Thank you for taking a shot, but no success so far. I'm not sure what
exactly happened, but now it won't turn on. I'll wait for the battery to
run out and try again tomorrow.

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Re: [linux-sunxi] Kernel damaged device?

[Luc Verhaegen]

On Sat, Aug 20, 2016 at 07:26:46PM -0700, Leonardo wrote:
> Hi. I'm building a very minimal Linux distro to use as an embedded system 
> on a A20 tablet. I don't want to believe this, but I think that booting my 
> distro has damaged the device. The tablet came with Android. I had it 
> rooted so I could extract the fex file. Then I got kernel 3.4.104 and uboot 
> 2016.02 from GitHub, built my file system with buildroot and so on. I'm 
> using an SD card for now. So I tried booting my system and nothing came up 
> on the LCD. Then I remove my SD card, try to get back to Android and still 
> nothing on the screen! The device is not dead. I can access it using ssh 
> over the wifi, the usb port works fine. Basically I can do anything 
> remotely. At first I thought I might have damaged something on the PCB 
> while performing the tests, so I had a second tablet. Boot on Android, 
> display works fine. Boot on my distro, nothing on screen. Try to get back 
> to Android, and nothing on the screen again. By the way, the backlight 
> lights up as usual, so the display is not dead also. I've worked on a 
> similar project last year and had no problem like this at all. I have no 
> idea what went wrong. Is it possible that my kernel has damaged the device 
> somehow?

Damage, no. Ruined nand content due to different settings, yes.

Thank allwinner for changing its mind on how to configure its nand 
controller in the middle of the A20 lifetime, while having code in 
its nand driver that clears the ram if it finds garbage.

Luc Verhaegen.

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[linux-sunxi] Kernel damaged device?

[Leonardo]

Hi. I'm building a very minimal Linux distro to use as an embedded system 
on a A20 tablet. I don't want to believe this, but I think that booting my 
distro has damaged the device. The tablet came with Android. I had it 
rooted so I could extract the fex file. Then I got kernel 3.4.104 and uboot 
2016.02 from GitHub, built my file system with buildroot and so on. I'm 
using an SD card for now. So I tried booting my system and nothing came up 
on the LCD. Then I remove my SD card, try to get back to Android and still 
nothing on the screen! The device is not dead. I can access it using ssh 
over the wifi, the usb port works fine. Basically I can do anything 
remotely. At first I thought I might have damaged something on the PCB 
while performing the tests, so I had a second tablet. Boot on Android, 
display works fine. Boot on my distro, nothing on screen. Try to get back 
to Android, and nothing on the screen again. By the way, the backlight 
lights up as usual, so the display is not dead also. I've worked on a 
similar project last year and had no problem like this at all. I have no 
idea what went wrong. Is it possible that my kernel has damaged the device 
somehow?

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