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

[Alexander Motin]

Henry Hu wrote:
> I've tried your driver, and it worked fine at my laptop.
> I have a Samsung R70, with built-in SD card reader(in fact, it can
> read many cards, and there are 4 unknown devices related to it).The
> transfer speed with dd bs=512 is almost 800KB/s, which I think is
> fairly fast.

bs=512 is a quite ineffective for any modern storage. With bigger bs you 
should get much bigger performance I think.

> I'm testing it with a transcend 2G mini SD card, with SD-miniSD adapter.
> I'm using 7-STABLE, so I changed kproc_create to kthread_create to
> compile the mmcsd module.
> There are errors, but the transfer completed normally.
> sdhci0-slot0: Card inserted
> mmc0: <MMC/SD bus> on sdhci0
> sdhci0-slot0: Command error 1 (opcode 8 arg 426 flags 101 dlen 0 dflags 0)
> sdhci0-slot0: Command error 1 (opcode 8 arg 426 flags 101 dlen 0 dflags 0)

This is not a problem. It means that your card does not support SDHC 
CMD8 command as it is not an SDHC actually.

> mmcsd0: 1950MB <SD Memory Card> at mmc0 16MHz/4bit

It means that top performance of this card on this controller is about 
8MB/s. I expect that you may reach it on read operations if your card is 
not very old.

-- 
Alexander Motin