Re: RFC: PCI SD host controller driver & mmc/mmcsd modules improvements

On Mon, Oct 06, 2008 at 12:58:28AM -0600, Warner Losh wrote:
> From: "Zaphod Beeblebrox" <zbeeble_at_gmail.com>
> Subject: Re: RFC: PCI SD host controller driver & mmc/mmcsd modules improvements
> Date: Mon, 6 Oct 2008 01:26:19 -0400
> 
> > On Sat, Sep 27, 2008 at 5:43 PM, Alexander Motin <mav_at_freebsd.org> wrote:
> > 
> > > Hi.
> > >
> > > I would like to present initial revision of my generic PCI SD Host
> > > Controller driver (sdhci). It support PCI devices with class 8 and subclass
> > > 5 according to SD Host Controller Specification. With some limitations it
> > > successfully works on my Acer TM6292 notebook with ENE CB714 card reader.
> > >
> > 
> > 
> > > Things that are not working yet:
> > >  - DMA modes (code is written, but as my controller looks like has broken
> > > DMA I have no ability to debug it),
> > >  - card insert/remove detection (need more thinking), you should reload mmc
> > > module to rescan cards,
> > >  - SDHC and MMC cards (have no such cards now to debug that code), only
> > > standard capacity SD Memory cards up to 4GB size are supported now,
> > >  - high speed (double rate) bus mode (need more thinking and DMA support).
> > 
> > 
> > Most 4G cards are SDHC that I've seen.  The notes on this that I've read
> > talk about the fact that you can have a 4G regular SD card but that many
> > (most) devices don't support it because of the need for a larger FAT to
> > support 4G.
> 
> s/many/a few/g.  4GB SD cards work fine in every device I've tried
> them in...

You are quite lucky then.
4G-SD are non standard and I have a few devices where they don't
work with.
Sadly I even own a USB reader, which is still being sold, that doen't work
with 2G cards - it just truncates them at 1G - sigh.

-- 
B.Walter <bernd_at_bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.