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

[Warner Losh]

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...

> I have two laptops with these controllers, but I have only SDHC media (4 and
> 8 gig cards).

Yes.  The SDHC isolation protocol and media decoding stuff isn't
written yet.

Warner