[U-Boot] [PATCH v2 0/5] Enable caches for the RPi2

[Stephen Warren <swarren@wwwdotorg.org>]

On 03/16/2016 08:41 AM, Alexander Graf wrote:
> This patch set converts the Raspberry Pi 2 system to properly make use of
> the caches available in it.
>
> Because we're running in HYP mode, we first need to teach U-Boot how to
> make use of HYP registers and the LPAE page layout which is mandated by
> hardware when running in HYP mode.
>
> Then while we're at it, also mark the frame buffer cached to speed up
> screen updates.
>
> With this patch set, my Raspberry Pi 3 running in AArch32 mode is a *lot*
> faster than without.
>
> Please verify that the code works on a RPi2 as well and doesn't break the
> original Pi. In theory it should work, but I only have a 3 to test on
> available here.

I did find one quirk with this series (as tested in my rpi_dev branch on 
github): HDMI console scrolling is now extremely fast for 32-bit builds. 
However, it's noticeably slower on the 64-bit RPi 3 build. I wonder if 
the DCACHE_* constants aren't optimal for AArch64? Perhaps this can all 
be explained instead by RPi 3 needing a slower core clock to support a 
fixed mini UART frequency; that probably slows down the ARM access to DRAM.