Hi
2009/4/30 alfred steele alfred.jaquez@gmail.com:
Hi Magnus,
The mainline u-boot + my patches from early April does not contain any driver for the i.MX31 NAND flash controller so that can't autodetect any flash part at all.
How does it boot out of NAND then? I am getting confused. By detection, i meant the basic init of the NFC and the NFCBUF and the associated initiliazation to pool the SPL off the NAND which further hand over to the uboot.
I realize I wasn't clear. U-boot NAND booting is done in several steps. For the i.MX31 the following steps are involved: 1. i.MX31 reads the first 2048 bytes from NAND. This is the SPL. 2. The SPL contains lowlevel-init and sets up the SDRAM (in assembler). SPL is compiled without SKIP_LOWLEVEL_INIT and without SKIP_RELOATE_UBOOT. 3. The SPL copies the rest of U-boot, a predefined number of blocks, from NAND to SDRAM (nand_boot_mx31.c). This is currently done without run-time detection of the NAND type.CFG_NAND_CHIP_SIZE/CFG_NAND_PAGE_SIZE and others control this. 4. After copying, SPL jumps to U-boot 5. U-boot starts executing (cpu/arm1136/start.S) 6. SKIP_LOWLEVEL_INIT and SKIP_RELOCATE_UBOOT are defined when compiling U-boot since the SDRAM has already been setup by SPL and SPL has already placed U-boot at the correct address (i.e. no relocation needed). 7. Eventually board/freescale/mx31pdk/mx31pdk.c:board_init is called. 8. U-boot main loop is entered.
(I hope I got the above right)
If U-boot had full NAND support for i.MX31, NAND would be detected somewhere between steps 7 and 8.
Remember that there are two separate applications involved above, SPL which is built in nand_spl, and U-boot. The two applications are concatenated into one binary. What's may be confusing is that the same config-file is used both when compiling SPL and U-boot, but config.h is modified a bit.
CONFIG_NAND_SPL is defined in nand_spl/board/freescale/mx31pdk/Makefile when it builds the second phase loader.
CONFIG_NAND_SPL is fine but CONFIG_SKIP_LOWLEVEL_INIT and CONFIG_SKIP_RELOCATE_UBOOT should not be defined in case we are booting out of NAND, right?
See my explanation above. CONFIG_SKIP* is defined when compiling U-boot, but not when compiling SPL.
/Magnus