Messages in this thread | | | Date | Fri, 1 Apr 2016 22:17:54 +0200 (CEST) | From | Stefan Wahren <> | Subject | Re: [PATCH 2/3] ARM: multi_v7_defconfig: Switch BCM2835 to sdhci-iproc.c for MMC |
| |
Hi,
> Stephen Warren <swarren@wwwdotorg.org> hat am 1. April 2016 um 18:58 > geschrieben: > > > On 03/31/2016 08:01 PM, Stephen Warren wrote: > > 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. > > Ah, now I realize that sdhci-bcm2835.c and sdhci-iproc.c are two > alternative drivers for the same HW device. For some reason I got the > incorrect impression from some past email/patch discussion that > sdhci-iproc.c was a driver for the alternative SD controller in the chip. > > So, there's no problem with this patch. > Acked-by: Stephen Warren <swarren@wwwdotorg.org> > > (although /me wonders why sdhci-iproc.c was even added in the first > place given sdhci-bcm2835.c pre-dates it by over 2 years, and equally > why the new driver is any faster given it looks almost identical and > accesses the same HW, but I suppose it doesn't matter).
my old results (without DMA support) wasn't so impressing:
sdhci-bcm2835
378 kB/s WRITE 10,6 MB/s READ
sdhci-iproc
881 kB/s WRITE 10,8 MB/s READ
The performance gain comes from the more intelligent quirk handling. sdhci-bcm2835 has a fixed delay after each write.
Regards Stefan
> > _______________________________________________ > linux-rpi-kernel mailing list > linux-rpi-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-rpi-kernel
| |