[U-Boot] [PATCH v3] dfu: Introduction of the "dfu_hash_algo" env variable for checksum method setting

[Wolfgang Denk]

Dear Lukasz,

In message <20140515154334.626923b4 at amdc2363> you wrote:
> 
> > This reinforces my speculation that you are actually addressing the
> > wrong problem.  Instead of adding new code and environment variables
> > and making the system even more complex, we should just leave
> > everything as is, 
> 
> During working on this patch I've replaced the crc32() method with the
> call to hash_method(), which IMHO is welcome.

Yes, indeed this is highly welcome.  Thanks a lot for that!

> I also don't personally like the crc32, hence I like the choice which
> this patch gives me to use other algorithm (for which I've got HW
> support on my platform - e.g. MD5).

Well, is this really useful?  dfu-utils provides only CRC caculation,
so where would you get the reference value for any other checksum metod
from?

> > and you should try to find out why the CRC
> > calculation is so low for you.  Checking if caches are enabled is
> > probably among the things that should be done first.
> 
> L1 is enabled. L2 has been disabled on purpose (power consumption
> reduction). 

This certainly contributes to slow code execution.

> Please note that the last revision of DFU is from 2004. I've contacted
> Greg KH (one of the original authors) and he replied that no new attempt
> to revise the standard was made. 

This may just mean that users were just happy with the current
situation.  It's definitely better than if changed had been proposed
but rejected.

> The best however, would be to revise the standard to include such
> functionality to it. In the same time I'm fully aware that this is
> very unlikely to happen.

Why do you think it is unlikely?  Of course, it would require that
someone comes up with such a proposal in the first place.  But you
sound as if you were certain a proposal had no chance for being
considered.  I may be naive, but should we not at least try before
giving up?

Best regards,

Wolfgang Denk

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