Date: Wed, 29 Oct 2014 15:27:16 -0600 From: Ian Lepore <ian@FreeBSD.org> To: Warner Losh <imp@bsdimp.com> Cc: "freebsd-arm@freebsd.org" <freebsd-arm@FreeBSD.org>, ticso@cicely.de Subject: Re: sd card probing (was: FreeBSD 10.0 on Raspberry PI B+ no network devices Message-ID: <1414618036.17308.146.camel@revolution.hippie.lan> In-Reply-To: <6CC5D29F-C3F7-4913-9D77-D275EEDDC1DD@bsdimp.com> References: <53FD1646.2010103@ceetonetechnology.com> <20140827021349.1273f703c6756d07fad72a16@schwarzes.net> <20141014032743.GK38905@cicely7.cicely.de> <20141014041305.GM38905@cicely7.cicely.de> <CAB=2f8wiBLRYBVHUw-PptzQE-QP3%2B1EmHFMMMipZWi_dUG9m8w@mail.gmail.com> <20141022204454.GA12231@cicely7.cicely.de> <CAB=2f8xHEeF8DtP1eCkpp3Y0rZu3w0Phi_gzMSByGJ74xaFchg@mail.gmail.com> <20141023022244.GB16490@cicely7.cicely.de> <20141029172937.GB59614@cicely7.cicely.de> <1414605501.17308.97.camel@revolution.hippie.lan> <20141029200403.GC59614@cicely7.cicely.de> <1414613786.17308.124.camel@revolution.hippie.lan> <6CC5D29F-C3F7-4913-9D77-D275EEDDC1DD@bsdimp.com>
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On Wed, 2014-10-29 at 14:59 -0600, Warner Losh wrote: > On Oct 29, 2014, at 2:16 PM, Ian Lepore <ian@FreeBSD.org> wrote: > > > On Wed, 2014-10-29 at 21:04 +0100, Bernd Walter wrote: > >> On Wed, Oct 29, 2014 at 11:58:21AM -0600, Ian Lepore wrote: > >>> On Wed, 2014-10-29 at 18:29 +0100, Bernd Walter wrote: > >>>> On Thu, Oct 23, 2014 at 04:22:44AM +0200, Bernd Walter wrote: > >>>>> On Wed, Oct 22, 2014 at 11:43:01PM -0200, Luiz Otavio O Souza wrote: > >>>>>> On 22 October 2014 18:44, Bernd Walter wrote: > >>>>>>> On Tue, Oct 14, 2014 at 12:51:50PM -0300, Luiz Otavio O Souza wrote: > >>>>>>>> On 14 October 2014 01:13, Bernd Walter wrote: [...] > >>> > >>> Pullups on sd signal lines is a recent thing. It's in the sd 4.x > >>> physical spec, in the form of requiring the standard sd data lines be > >>> pulled high or low when using the new UHS-II signals. Other than that > >>> pullups are not required on any of the lines for sd cards. At work we > >>> don't put pullups on any of them, and use a 22 ohm series on just the > >>> clock line, and that only on designs where we have to fly across a > >>> ribbon cable to get to the card socket. > >> > >> Can't say since when it is in the SD spec, saw it in the MMC, but don't > >> know how long it is there either. > >> Anyway - I remember them well, because I had to hand wire them on my > >> RM9200 prototype boards. > >> It never had been a problem until Warner added higher speed support, but > >> I don't have series resistors on my boards. > > High speed on the RM9200 boards was always a bit dodgy anyway. :( Sorry for the hassle. > Actually high-speed works fine by itself, it's the combo of high-speed and 4-wire that's problematic, because of dma overruns. It's especially bad when usb is also active, because it gets priority on the bus. If the mci dma doesn't get a bus-grant in time, it's not smart enough to stop the clock to the card, and it just looses data instead. All in all, the max reliable data rate is around 3 MB/sec when usb is enabled. -- Ian
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