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Am1808 problem on USB

gogo49087
Prodigy 150 points
Other Parts Discussed in Thread: AM1808, DA8XX, OMAP-L138

Hi, I'm working on my home-made am1808 board, and linux-2.6.37 from  DaVinci-PSP-SDK-03.20.00.14.

The problem is, if I enable usb, the kernel failed to boot (nothing output from uart2), and the AM1808 was HOT (POWER will rise 500mW).

If I don't call da850_evm_usb_init from arch/arm/mach-davinci/board-da850-evm.c, the linux boots successfully without USB function.

And I tried to call da850_evm_usb_init, but commented

 

// ret = da8xx_register_usb20(1000, 3);

the kernel can boot to "Waiting for USB PHY clock good...".

 

What is the problem?

 

And this is my second am1808 board, this one uses MII interface. The first one uses RMII interface and have no problem with USB. And the both have the same USB schematic.

 

Thank you & best regards!

 

  • 0
    Expert 2021 points

    Hello, I am having the exact same problem.  Were you able to find a solution?  If so, I would very much appreciate a sentence or two describing the crux of the problem.  Thank you!

  • 0
    Expert 2021 points

    I figured out the problem... on my custom board, the USB reference clock (48 MHz) is supplied externally (USB_REFCLKIN).  This is not the case on the evaluation board.  I needed to change the settings in the CFGCHIP2 register to select the correct USB 2.0 PHY clock input frequency (bits 3-0) and USB PHY reference clock source (bit 11 for USB2.0 and bit 12 for USB1.1).  In my case, with an OMAP-L138 using DaVinci-PSP-SDK-03.21.00.04, the changes are in linux-03.21.00.04/arch/arm/mach-davinci/board-da850-evm.c.