Hi Ravi, > Hi Lukasz > > >> >One question: > >> > >> >Would it be possible to develop SPL (MLO) for your platform, > >> >which does following things: > >> > >> >1. Loads the full-fledge u-boot to SDRAM 2. Starts the u-boot and > >> >3. u-boot flash all the needed stuff > >> > >> >By using such approach we could restrict our dfu support in SPL > >> >u-boot only to receiving data and uploading it to SDRAM (i.e. we > >> >wouldn't need to add write support for ext, fat and eMMC). > >> > >> > >> This is not possible, because combining MLO and u-boot.img will > >> not fit in IRAM (512k). The u-boot.img itself is around 640K. > > >My point here is to first load SPL u-boot (which size is around 110 > >KiB), and then download via DFU full-featured u-boot, which would be > >placed in SDRAM. > > Yes this is good idea, so the SPL-DFU will have only RAM device > support (to load u-boot into DDR). But we don't have DFU command to > jump to u-boot after loading u-boot into DDR.
I think that we don't need dfu command in SPL to boot fully-featured u-boot. Lets consider following scenario: - ROM bootloader (IPL) fetches SPL u-boot via USB. Then it passes execution to it. - The running SPL downloads fully-fledged u-boot [*] to RAM and passes execution to it (as it is done in board_init_r @ ./common/spl/spl.c). There is no need for any special command(s) to do that. - Fully-blown u-boot flashes all needed images and reboots the board. - Now the board is setup with proper u-boot, kernel and rootfs [*] - This version of u-boot only requires to have hardcoded "bootcmd" env variable. It would consist the list of commands needed for flashing your target board. The "dfu_alt_info" should be hardcoded as well. > The DFU basically just > download firmware to memory devices like mmc/sd/eMMC/RAM. > So the > question is how to transfer control to u-boot after downloading the > u-boot to DDR using SPL-DFU/RAM. Please consult board_init_r function at ./common/spl/spl.c > > >Then u-boot downloads and flash all needed images. > >One big advantage is that our SPL DFU support can be minimal - we > >don't need to implement fat, ext ,emmc write support. > > Yes, I agree, if we could workaround above bottle neck. > > Regards > Ravi > -- Best regards, Lukasz Majewski Samsung R&D Institute Poland (SRPOL) | Linux Platform Group _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
