On Fri, 31 Oct 2014 09:21:49 -0700 (PDT)
Dennis Kerrisk <dennisk8...@gmail.com> wrote:
> My Board is a Rev C boared.
>
> kernel is 3.4.90+,
>
> Uboot is:
> U-Boot 2014.04-10675-g44b53fd (May 23 2014 - 13:02:55) Allwinner Technology
> arm-linux-gnueabihf-gcc (Debian 4.7.1-7) 4.7.1
> GNU ld (GNU Binutils for Debian) 2.22
>
>
> There is a bad md5 after less than a dozen tries:
> bf66d2bd1a88c5720b0dc8d8ece43099 -
> bf66d2bd1a88c5720b0dc8d8ece43099 -
> bf66d2bd1a88c5720b0dc8d8ece43099 -
> bf66d2bd1a88c5720b0dc8d8ece43099 -
> bf66d2bd1a88c5720b0dc8d8ece43099 -
> 55b5d5b97cc18170891e8f8993bd19bc -
> bf66d2bd1a88c5720b0dc8d8ece43099 -
> bf66d2bd1a88c5720b0dc8d8ece43099 -
> bf66d2bd1a88c5720b0dc8d8ece43099 -
> bf66d2bd1a88c5720b0dc8d8ece43099 -
OK, thanks a lot for running tests and providing feedback. Your
A10-Lime appears to be the third one with this particular problem
confirmed.
And unlike other cases, it is not Rev A, which means that all A10-Lime
boards are potentially affected. Originally I thought that the problem
may be only in the early pre-production batch.
For the test results from my A10-Lime board, you can check the
following picture:
http://people.freedesktop.org/~siamashka/files/20140512/sunxi-cpufreq-plot.png
There the 'cyan' line shows how much voltage is need for my
A10-Lime board at each clock frequency to pass the libjpeg-turbo
decoding test without exhibiting problems. The 'blue' line is the
showing the cpufreq voltages used by the sunxi-3.4 kernel for
Allwinner A10. If the 'cyan' line is above 'blue', then we have clear
reliability problems. And if the 'cyan' line exactly matches the 'blue'
line, then the problems are not reproducible, but we have no safety
headroom (which is still not great).
If your board is behaving in a similar way, then you either need to
increase the voltage from 1.4V up to 1.45V for 1008MHz. Or reduce
the maximum clock frequency to 960MHz (it is using 1.4V voltage).
The voltage changes can be applied to the following table in the
sunxi-3.4 kernel sources (the 'sun4i_dvfs_table'):
https://github.com/linux-sunxi/linux-sunxi/blob/sunxi-v3.4.104-r0/arch/arm/plat-sunxi/cpu-freq/cpu-freq-table.c#L100
But the first simple test would be to reduce the CPU clock frequency,
make sure that the libjpeg-turbo based test does not detect any
problems, and then verify that your original SD card corruption
issue disappears too (if not, then we need to do even more
troubleshooting).
Please run some more tests, try different solutions and report
your findings. Then we can try to see, what can be done to
improve reliability for all A10-Lime users.
Thanks!
--
Best regards,
Siarhei Siamashka
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