Re: [PATCH 2/3] ARM: multi_v7_defconfig: Switch BCM2835 to sdhci-iproc.c for MMC

From: Stephen Warren
Date: Thu Mar 31 2016 - 22:02:09 EST

On 03/31/2016 06:28 PM, Eric Anholt wrote:
This approximately triples write performance for the SD card. My card
is too full of important data to collect very reliable numbers, but I
see 271.361% +/- 166.742% improvement (n=3 before, 6 after), for 'dd
if=/dev/zero of=/boot/asdf bs=1M count=3 oflag=dsync,direct'. Read
performance appears to be unaffected.

I thought that switching the defconfig wasn't possible, since this HW module relies on the SoC core clock, and that can be asynchronously changed by the FW running on the VideoCore. Consequently, this change isn't safe unless the user puts non-default options in their config.txt.

The same comment applies to "[PATCH 1/4] ARM: bcm2835: Switch BCM2835 to sdhci-iproc.c for MMC" in the other series.