cfi_cmdset_0001.c: Excessive erase suspends

[Alexey Korolev]

Hi Anders,

> With recent kernels I've been seeing a lot of these
> "Newly-erased block contained word 0xffff0000 at offset 0x00180000"
> on a board using Intel 28F640J5 flash chips.
> 
> It looks like the errors are caused by large amounts of erase suspends.
> Each erase gets suspended around 8500 times and in some extreme cases
> a lot more. The erase ends without any error bits set but it turns out
> that it has failed.
> 
> It seems like some flash chips have a limit on the number of times that
> the erase can be suspended. I have not seen any information on the Intel
> chips but a Spansion AppNote says 5,980 times for some of their devices
> before running the risk of an erase fail.
> 
We saw the similar  problem in our tests. As a possible solution I could
suggest to disable erase suspend on write. 

Regarding limit of suspend/resume cycles: it is rather unclear how many cycles would be ok how many cycles would be not. 
Special investigations are required here. 

Thanks,
Alexey