Sd/sdio On The Gp2x


DijiTao

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After doing a little research into the state of Secure Digital card drivers under Linux, and in particular the state of SDIO cards I’m getting increasingly concerned. To get started here’s a quote from the Wikipedia article on “Secure Digital card”

"Wikipedia" said:
Like most memory card formats, SD is covered by numerous patents and trademarks, and licensing is only available through the Secure Digital Card Association. The SD Card Association’s current licensing agreement does not allow for open-source SD drivers, a fact that generates a fair amount of consternation in the open-source and free software communities. The usual workaround is to develop an open-source wrapper for a closed-source SD driver available on the particular platform, but this is far from ideal. Another common workaround is to use the older MMC mode, which all SD cards are required to support by the SD standard.

So it’s possible that GPH has a licensing agreement with Secure Digital Card Association that has allowed GPH to write a closed source SD driver for the GPX2’s Linux implementation but it’s also possible that GPH simply resorted to using the SD card’s ability to fall back into MMC mode. Either way the community getting SDIO cards working in my mind seems like a long shot since the Open Source community as a whole apparently hasn’t had much luck with that. GPH has already seemed to say that they aren’t working on getting SDIO working. Given what I think I understand about the nature of SD it would seem that our only hope for getting SDIO working would be through GPH since only they would have the access to the necessary documentation (if they have even licensed SD) to write an SDIO driver. I have the distinct hunch that SD support on the GP2X is going to be completely done through MMC fall back and thus slow as mud, and no hope for SDIO devices.

Any reason I should think I'm wrong on this?
 
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Just because the docs arn't available doesn't mean we can't use the device - ever heard of reverse engineering? A lot of the GP2X will be closed source, but it'll just be RE'd.

As for SDIO, I'm very interested in that, as it's something I've never done before. In fact, I will sacrifice a Zodiac2 and SDIO Wifi card to get the information necessary - I just need a Zodiac compatible Wifi card, but these are expensive beasts.

As for normal SD cards, well, small SD cards are cheap, so I'll just buy a couple and play with them until either they break, or I write a prog that works :) Again, I can use a Zodiac2 (or even the GP2X if it does SD properly) to work out the protocol. I don't know how similar they are, but I guess my knowledge of SMC's should help here :)

(If anyone is wondering why I'd want to work out the SD Protocol on the GP2X to use it on the GP2X, it's because some emu's will not use linux for performance reasons, so I need to write a hardware level sdk, as GPH will only support Linux)
 
Vimacs posted on Sep 13 2005 at 02:09 PM said:
magiceyes (the developer of the soc in the gp2x) provides the drivers.

Magiceyes MMSP2 http://www.mesdigital.com/english/Products/product_mmsp2.asp is the heart of the GP2X I take it.

After looking over it's associated PDF's now I have a new consern. The SOC seems very WinCE centric, with out a single mention of the word Linux in it's Data Sheet PDF. This imparticular:

MP2520F’s 2D Graphic Processor accelerates the WinCETM GDI and Direct2DTM

Seeing something about OpenGL, X, or Linux in that PDF would have been nice. On the plus side the dev kit (http://www.mesdigital.com/english/Products/product_development.asp) is definatly what we saw in the video's cragix posted earlier, and it's webiste does make some reference to Linux:

Linux
ARM Linux Kernel 2.4.25
GNU Tool source and binary for RedHat Linux
U-Boot 1.0
Device Driver
File & File system
Shell & Shell utility, System Utility
Application support software
Media Middelware(Video/ Audio codec)

Also the Data Sheet PDF makes it clear that the SD controller is most definitely an SD controller and not just an MMC controller.

Hopefully the Linux kernel that comes with it will fully support all of it's hardware - if it does I think we'll be in pretty good shape.
 
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Squidge posted on Sep 13 2005 at 07:50 PM said:
Just because the docs arn't available doesn't mean we can't use the device - ever heard of reverse engineering? A lot of the GP2X will be closed source, but it'll just be RE'd.

As for SDIO, I'm very interested in that, as it's something I've never done before. In fact, I will sacrifice a Zodiac2 and SDIO Wifi card to get the information necessary - I just need a Zodiac compatible Wifi card, but these are expensive beasts.

As for normal SD cards, well, small SD cards are cheap, so I'll just buy a couple and play with them until either they break, or I write a prog that works :) Again, I can use a Zodiac2 (or even the GP2X if it does SD properly) to work out the protocol. I don't know how similar they are, but I guess my knowledge of SMC's should help here :)

(If anyone is wondering why I'd want to work out the SD Protocol on the GP2X to use it on the GP2X, it's because some emu's will not use linux for performance reasons, so I need to write a hardware level sdk, as GPH will only support Linux)

Ha, that is the spirit of a true rocket scientist!
Go Squidge, go Squidge :D
 
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