Re: [PATCH v1] crypto: driver for tegra AES hardware

[Varun Wadekar <vwadekar-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

> it's not - it saves writes.

Are you ok with this solution? Either way I wan to start with a clear
key table before programming the hardware.

> why do you need to clear the entire key table if it will be
> overwritten anyway?

If you set a > 128-bit key and then set a 128-bit key, the remaining
bits still remain in the key table. Similarly, if we use updated IV in
one operation and want to use the initial IV for the next, the updated
IV will still remain in the key table. The entire key table is copied to
the AES engine. Even though, we program the engine with the exact number
of bits to use for the key and whether to use the updated/initial IV, I
feel its better if the unused bits are zero instead of having garbage.