Hi, I have 2 OMAPL138/AM1808 boards: one with mDDR and ther other with SDRAM. I am looking at options to reduce power consumption. One the of options we are looking into is the cpu frequency. Not having a lot of success with the SDRAM board. Here is a little list of what I tried (with the Arago tree).
1) I have tried enabling the cpu frequency scaling. It works with the mDDR board but any change in frequency fails when using the SDRAM board. I am guessing this is because the DDR is derived from PLL1 while the SDRAM uses PLL0. Is there a way to make the cpu frequency work or is this impossible with SDRAM? 2) With the SDRAM board, I then tried downclocking the cpu directly in the bootloader using the AISgen utility. Under the PLL0 tab, I modified by DIV1 from 1 to 2 to operate the CPU at 150Mhz instead of 300Mhz while preserving my SDRAM at 100Mhz. With this, the kernel hangs at boot during the SATA initialization (I can reach the console fine if I disable the AHCI). I looked at the SATA controller datasheet but couldn't find a link between the SYSCLK1 and the SATA (since DIV1 affects SYSCLK1, right?). 3) Similar to #2, I changed the PLL0 settings post-divider (2 to 3) and div3 (3 to 2). This gave me CPU 200 Mhz (with settings matching what is found under da850_opp_200 in da850.c) and still keeping the 100Mhz SDRAM. This configuration stalls during the kernel boot right after the reset of unused clocks. I would appreciate if anyone had some information on either how to fix these issues or other ways to do this. Thanks and regards Marc _______________________________________________ Davinci-linux-open-source mailing list [email protected] http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
