Date: Tue, 20 Jan 2009 11:50:31 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: mav@FreeBSD.org Cc: freebsd-arm@FreeBSD.org Subject: Re: Mount root from SD card? Message-ID: <20090120.115031.2008400028.imp@bsdimp.com> In-Reply-To: <4976135A.3070109@FreeBSD.org> References: <1232450582.00063538.1232438401@10.7.7.3> <49760E8E.1000609@FreeBSD.org> <4976135A.3070109@FreeBSD.org>
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In message: <4976135A.3070109@FreeBSD.org>
Alexander Motin <mav@FreeBSD.org> writes:
: Alexander Motin wrote:
: > Krassimir Slavchev wrote:
: >> -----BEGIN PGP SIGNED MESSAGE-----
: >> Hash: SHA1
: >>
: >> M. Warner Losh wrote:
: >> ...
: >>> mmcsd0: 1983MB <SD Memory Card> at mmc0 30MHz/1bit
: >>> Trying to mount root from ufs:/dev/mmcsd0s1
: >>>
: >>> Manual root filesystem specification:
: >>> <fstype>:<device> Mount <device> using filesystem <fstype>
: >>> eg. ufs:/dev/da0a
: >>> ? List valid disk boot devices
: >>> <empty line> Abort manual input
: >>>
: >>> mountroot> ?
: >>>
: >>> List of GEOM managed disk devices:
: >>> mmcsd0
: >>>
: >>>> Looks like that should be working.
: >>>> mav@ has done a lot of hacking on the mmc code...
: >>>> Do you have 1 wire or 4 wires for your mmc bus on your board?
: >>
: >> On the board all 4 bus wires are connected (MCD A0-A3) but I've never
: >> seen working 4-bit mode on AT91RM9200 (See PR128987 too).
: >
: > I have just committed MMCBR_IVAR_CAPS implementation into CURRENT.
: > Without having it implemented, results can be unpredictable. For
: > example, mmc layer could enable high-speed timings to reach 30MHz, but
: > this mode is not implemented for this controller. Booting with verbose
: > messages enabled could give a bit more information.
: >
: > What's about 4-bit mode, I see some sc->wire4 variable checked by the
: > driver, which is never initialized. I don't very understand how this
: > thing expected to work.
:
: As I can see from specification, if sc->wire4 is set to 0 by default,
: bus will not ever switched into 4bit mode. Try to just comment out " &&
: sc->wire4" part of at91_mci.c. If this variable expected to report real
: bus width, then it probably should be done in different way, by
: reporting correct host capabilities.
sc is initialized to 0 by the bus layer, so I don't think this will
have an effect. You are correct that this should be generic in the
board-level specific meta-data for each at91 board. That stuff just
isn't there yet.
The problem is, I think, that something broke in the series of commits
and now reads don't work at all anymore. After the first couple in
the series, I didn't test the follow on commits due to time.
Warner
: > PS: For MMC cards bus width testing routine implemented. May be we could
: > do something alike for SD cards. It is not part of SD specification, but
: > may be we could just issue some other command, transferring data, to
: > check effective bus width.
:
: --
: Alexander Motin
:
:
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