Hi folks, I eventually decided that I did need to figure out the DRAM timings for the Micron chip on my board, but I found an easier way than actually "understanding what I'm doing"! :-)
I pulled the vendor U-Boot image off the flash, skipped the appropriate number of bytes until I was actually dealing with a u-boot.sb formatted image (looking for the STMP signature I found in the compiled mainline u-boot), then used the Rockbox project's sbtoelf tool to convert the SB back to two ELF files, the SPL.elf and the u-boot.elf. From there I loaded the SPL.elf into ghidra, then went looking for byte sequences found in arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c to see if I could locate them in the vendor blob. I did, right at the end of the binary, then converted bytes into uint32 sequences so that I could compare with the mxs_dram_vals for CONFIG_MX28. Did the compare and found a single bit that is different between the two sequences of initialisation values. Literally a 1 to a 0, and that is all. So I built mainline with that change, and an updated iomux_setup because the Wink Hub v1 uses MX28_PAD_I2C0_SCL__DUART_RX and MX28_PAD_I2C0_SDA__DUART_TX for its console pins. i was hoping to see it boot via mxsldr, but unfortunately, I got nothing. How can I get the SPL to emit something on the console to confirm it is running? i.e. before the DRAM initialisation? Regards, Rogan On Wed, 23 Aug 2023 at 17:56, Rogan Dawes <ro...@dawes.za.net> wrote: > Hi Fabio, > > On Tue, 22 Aug 2023 at 13:44, Fabio Estevam <feste...@gmail.com> wrote: > > > > Hi Rogan, > > > > On Tue, Aug 22, 2023 at 6:42 AM Rogan Dawes <ro...@dawes.za.net> wrote: > > > > > > Hi Fabio, > > > > > > As far as I am aware, the U-boot source for the Wink hub has not been > > > made available anywhere. That said, the RAM chip in use on the board > > > > Was there a formal request for the U-Boot source code to Wink? > > > > As per the GPL license, they have to share the U-Boot source code. > > > > I have just asked them for it, so let's see what happens. I'm not > optimistic, though, given their financial troubles. I am not aware of > anyone else asking them. However, I do believe that there have been > requests for the kernel sources for the Wink Hub 2, which were > ignored, suggesting that they are not the best GPL citizen. > > > > is marked D9LPX, which apparently corresponds to the following item: > > > > https://media-www.micron.com/-/media/client/global/documents/products/data-sheet/dram/ddr2/512mbddr2.pdf?rev=2c70f8a2b207452584b2bf040de8d771 > > > > There is a tool from NXP that helps with the i.MX28 DDR2 controller > > initialization for a specific DDR model: > > > > > https://community.nxp.com/pwmxy87654/attachments/pwmxy87654/imx-processors/9552/1/MX28_DDR2_register_programming_aid_v0.2.xlsx > > > > The DDR initialization values obtained from this tool are then used in > > U-Boot inside the 'mxs_dram_vals' array. > > > > There is a common DDR configuration at > > arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c. > > > > Most likely, in your case, it will require a custom mxs_dram_vals > > initialization, like it is done at board/liebherr/xea/spl_xea.c. > > > > > I did try to change the iomux_cfg_t as suggested above, built using > > > make mx28evk_defconfig && make u-boot.sb, and used mxsldr to try load > > > it, to no avail. There was no output on the serial port at all, or any > > > other suggestion that anything was running. > > > > It has been a long time since I used the mxsldr tool. > > > > When time permits, I can try to load a recent U-Boot over USB using > > this tool on a imx28-evk. > > > > Cheers > > I think fiddling with RAM timings is a little more in the weeds than I > am ready to go at this point. I did see this post > (http://web.archive.org/web/20151005053615/http://jalderman.org/?p=348), > suggesting that it was not too difficult to get it working using > mainline u-boot. That said, I also note that some teardowns mention > that the RAM is a Nanya part, while I have Micron, so perhaps I should > not place too much reliance on that. > > Rogan >
