From: Stefan Wahren <stefan.wahren@i2se.com>
To: Eric Anholt <eric@anholt.net>, Stephen Warren <swarren@wwwdotorg.org>
Cc: Russell King <linux@arm.linux.org.uk>,
linux-kernel@vger.kernel.org,
Florian Fainelli <f.fainelli@gmail.com>,
linux-rpi-kernel@lists.infradead.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/3] ARM: multi_v7_defconfig: Switch BCM2835 to sdhci-iproc.c for MMC
Date: Fri, 1 Apr 2016 22:17:54 +0200 (CEST) [thread overview]
Message-ID: <1330015558.68271.961ea0e5-8785-4a9b-803a-599a405ed7c7.open-xchange@email.1und1.de> (raw)
In-Reply-To: <56FEA8BA.8020307@wwwdotorg.org>
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
WARNING: multiple messages have this Message-ID (diff)
From: stefan.wahren@i2se.com (Stefan Wahren)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/3] ARM: multi_v7_defconfig: Switch BCM2835 to sdhci-iproc.c for MMC
Date: Fri, 1 Apr 2016 22:17:54 +0200 (CEST) [thread overview]
Message-ID: <1330015558.68271.961ea0e5-8785-4a9b-803a-599a405ed7c7.open-xchange@email.1und1.de> (raw)
In-Reply-To: <56FEA8BA.8020307@wwwdotorg.org>
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 at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-rpi-kernel
next prev parent reply other threads:[~2016-04-01 20:18 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-01 0:28 [PATCH 1/3] ARM: multi_v7_defconfig: Add more BCM2835 support Eric Anholt
2016-04-01 0:28 ` Eric Anholt
2016-04-01 0:28 ` [PATCH 2/3] ARM: multi_v7_defconfig: Switch BCM2835 to sdhci-iproc.c for MMC Eric Anholt
2016-04-01 0:28 ` Eric Anholt
2016-04-01 2:01 ` Stephen Warren
2016-04-01 2:01 ` Stephen Warren
2016-04-01 15:48 ` Eric Anholt
2016-04-01 15:48 ` Eric Anholt
2016-04-01 16:58 ` Stephen Warren
2016-04-01 16:58 ` Stephen Warren
2016-04-01 20:17 ` Stefan Wahren [this message]
2016-04-01 20:17 ` Stefan Wahren
2016-04-01 0:28 ` [PATCH 3/3] ARM: multi_v7_defconfig: Build in DWC2 USB support Eric Anholt
2016-04-01 0:28 ` Eric Anholt
2016-04-01 2:04 ` [PATCH 1/3] ARM: multi_v7_defconfig: Add more BCM2835 support Stephen Warren
2016-04-01 2:04 ` Stephen Warren
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