GP2X U-boot Memcard Support?

[MiniMoose]

I was skimming the U-Boot README file this morning and noticed he following:

MMC Support:
The MMC controller on the Intel PXA is supported. To
enable this define CONFIG_MMC. The MMC can be
accessed from the boot prompt by mapping the device
to physical memory similar to flash. Command line is
enabled with CFG_CMD_MMC. The MMC driver also works with
the FAT fs. This is enabled with CFG_CMD_FAT.

It seems that U-Boot has a built-in driver for the Intel ARM MMC units. Since MMC and SD are supposed to be identical electrically, I wonder if this driver will work on the GP2X out of the box?

 

[Squidge]

GP2X uses a version of U-Boot that does not support MMC/SD.

 

[DJWillis]

MiniMoose,

U-Boot will need patching and reflashing to the GP2X (and a lot of debugging, GP2X bricking etc.) to support that on the GP2X, the hardware interface for MMC/SD is the same (i.e. standard) but the chipset support is far from it most of the time.

If you want to get stuck into the code I put it up on Open2x and I am working on some U-Boot patches (will start to add them to CVS soon) to bring it upto 1.1.3 but I am not conviced that anybody really wants to play with U-Boot unless they have a jTag setup handy .

 

[Squidge]

Much easier and safer to launch a seperate prog from uboot itself. . .

 

[DJWillis]

Much easier and safer to launch a seperate prog from uboot itself. . .

​

Amen to that .

 

[MiniMoose]

Much easier and safer to launch a seperate prog from uboot itself. . .

​

Couldn't you just test your U-Boot changes by launching your version from the flashed version? Then once you're satisfied that your changes work, then flash it to your firmware.

Speaking of JTAG, does anybody know what hardare and software you need to get JTAG working under Linux and more importantly with GDB?

Squidge, how are you debugging your apps?

 

[Squidge]

Couldn't you just test your U-Boot changes by launching your version from the flashed version? Then once you're satisfied that your changes work, then flash it to your firmware.

Problem with that is many things are already configured by the first u-boot, so we wouldn't know if the second version worked until we flashed it and possibly bricked the gp2x. Much easier to just ask the current version to load and run an application (such as a launcher) from nand.

Squidge, how are you debugging your apps?

​

I don't debug them, I just make sure there's no bugs before uploading them to the gp2x

If something doesn't work as planned, then I output stuff to the serial port or LCD to show certain info to aid in the debugging.

 

[DJWillis]

Speaking of JTAG, does anybody know what hardare and software you need to get JTAG working under Linux and more importantly with GDB?

Squidge, how are you debugging your apps?

​

Ok, I am not Squidge but using jTag to debug is OTT when a simple serial connection should be fine. I am currently working the kinks out of GDB and adding to my GCC 4 tool-chain (I have it working with some really strange errors when I try on real H/W) so that should give you all the debugging you need.

jTag hardware is not hard to build but it needs to be re'ed as GPH don't (yet) publish the exact pinouts.