Performance lower than expected with BCM4359/9 on S905X2

[Jerome Brunet]

>
> I was not asking anyone to reproduce my exact setup.
>
> I find it confusing that some assume there is something different
> about the board I'm using. The more likely hypothesis is that all
> S905X2 boards have the same behavior.

High-speed MMC modes are usually defined/limited per boards.
Check the different  DTs in arch/arm64/boot/dts/amlogic, you'll see
that not all have the same configs.

Yes the S905X2 has the bounce buffer work-around which plays a role on
the overall performance. MMC high-speed modes is critical just has well.

The Amlogic 4.9 downstream does all kinds of fancy (and unsafe) things
to enable higher modes.

So there is no assumption here, merely a tentative to get a clearer
picture.

>
> Regards