Date: Thu, 3 Mar 2011 23:04:35 +0100 From: Bernd Walter <ticso@cicely7.cicely.de> To: Warner Losh <imp@bsdimp.com> Cc: freebsd-arm@freebsd.org Subject: Re: arm/155214: [patch] MMC/SD IO slow on Atmel ARM with modern large SD cards Message-ID: <20110303220435.GP86812@cicely7.cicely.de> In-Reply-To: <4D6FF142.9020801@bsdimp.com> References: <201103030040.p230eBIt023558@freefall.freebsd.org> <4D6EE744.5050100@ansley.com> <4D6FF142.9020801@bsdimp.com>
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On Thu, Mar 03, 2011 at 12:51:30PM -0700, Warner Losh wrote: > On 03/02/2011 17:56, Greg Ansley wrote: > >On 3/2/11 7:40 PM, Ian Lepore wrote: > >>The following reply was made to PR arm/155214; it has been noted by > >>GNATS. > >> > >>From: Ian Lepore<freebsd@damnhippie.dyndns.org> > >>To: ticso@cicely.de > >>Cc: FreeBSD-gnats-submit@freebsd.org > >>Subject: Re: arm/155214: [patch] MMC/SD IO slow on Atmel ARM with modern > >> large SD cards > >>Date: Wed, 02 Mar 2011 17:21:09 -0700 > >> I have not tested with 4-bit enabled; I wasn't aware (but in > >>retrospect > >> I probably should have assumed) that the hardware bugs are different > >> with 4-bit enabled. I'm not even sure our hardware design carries > >>all 4 > >> lines to the card; I'll look at the schematics and if they're > >>connected > >> I'll see about testing that mode. (And if they're not I'll see about > >> having our designers wire up all 4 lines on future designs.) > >> > >> I also haven't tested with the SAM9-series, because I don't have that > >> hardware available. (I hope to convince our hardware designers to > >> migrate us to SAM9 this year.) > >> > >With the current code (prepatch) 4bit mode is known to work at least > >on the SAM9G20 with kernel option AT91_MCI_HAS_4WIRE. I'll be working > >on the SAM9G20 in the next few days and I can test the patch on both a > >RM9200 (1 bit only) and on a couple of SAM9G20 designs with 4bit > >hardware. > > For some ancient history... > > The Atmel Linux repo went back and forth on the 4-bit support in > RM9200. When the SAM9260 was released, they added support there and > specifically disabled it for the RM9200. When I asked about it, they > muttered something about silicon bugs. After that, it ping ponged back > and forth between supported and not for a while. I honestly don't know > where it settled finally. Interesting. I'm not aware of 4-bit silicon bugs, but of course there are boards, which are 1-bit wired only. And I'm aware that you need 100k pullup or pulldown to the data wires, although my first prototype boards worked fine without them. I don't remember the reason for them. -- B.Walter <bernd@bwct.de> http://www.bwct.de Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.
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