SD card capped at 6 MB/s

[lockheed]

I just discovered that the card in Arch ARM RPi is capped at 6MB/s read speed even though through USB interface, it gets 15MB/s. I found a thread on RPi forum http://www.raspberrypi.org/forums/viewt ... =63&t=5057
which indicates that there was limitation of clock frequency on this interface and to fix it, some patch was introduced into Raspbian kernel.

But why is it not working on Arch 3 years later?

[moonman]

kernel source is the same for us and them. Config is different. Test your card in raspbian and I am pretty sure the speed will be the same. If not, then it must be kernel config.

[lockheed]

So what kernel options should I use to get it to work properly?
Are those safe?

cmdline.txt
$this->bbcode_second_pass_code('', 'sdhci-bcm2708.enable_llm=1 sdhci-bcm2708.sync_after_dma=0 sdhci-bcm2708.emmc_clock_freq=200000000')

config.txt
$this->bbcode_second_pass_code('', 'init_emmc_clock=200000000')