[OpenWrt-Devel] [PATCH] brcm63xx: Let the CFE partition in HG556a to be writeable

Jonas Gorski jogo at openwrt.org
Mon Jan 18 08:15:32 EST 2016


On Wed, Dec 2, 2015 at 9:37 PM, dani <dgcbueu at gmail.com> wrote:
> In the HG556a router the partition mtd0, where CFE lives, is read only.
> This patch allows this partition to be writeable.
> The BCM6358 SoC has two cores, but they are not identical. The second core has
> half icache.
> core0: icache=32kB
> core1: icache=16kB
> As default the HG556a uses the second core as the main one (configured by CFE).
> Since currently there isn't SMP support for using both cores, we want to use the
> one with the best performance.
> For using the core0 as the main one, we need to write some bytes at the offset
> 0x014 of mtd0 (CFE). Therefore we need the mtd0 partition to be writeable.
> After setting the core0 as the main one, the performance can increase up to
> +20% (tested). The performance gain isn't marginal.
> For setting the core0 as the main one in an easy way I wrote a very simple utility:
> https://wiki.openwrt.org/_media/media/huawei/tp0set.tar.gz
> It can switch from core0 to core1 or vice versa in OpenWrt writing proper bytes
> into bcm6358 CFE (fully tested in the HG556a, no bricks).

To be honest, I'm not very comfortable with making the CFE partition
writable, and rather add code to lzma-loader that switches back to
thread 0, then add lzma-loader for the affected devices.

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