Our company's board uses CUS package of the DM3730. It has HSUSB2_XXX pins connected to an external USB PHY which is connected to a USB HUB which in turn has one of its downstream ports connected to the SMSC95XX USB bridge.We have several difficulties while trying to make such setup work for us with the latest U-Boot code from the git.denx.de (We want to use Denx.de code because it supports SMSC95XX ethernet bridge).Here are the difficulties:1. If U-Boot's code is used as-is the first point of failure for us (in the code) is the inability to perform software reset through
the UHH_SYSCONFIG (CPU just immediately jumps to the "data_abort" exception handler)TRM documentation for the CM_CLKSEL2_PLL register states that there shall be proper initialization of the
'SD_DIV' and 'DCO_SEL' fields of the CM_CLKSEL2_PLL register and after adjusting U-Boot's code according to the
latest TRM it seems that software reset through the UHH_SYSCONFIG started working.2. Immediately after issuing of software reset through the UHH_SYSCONFIG U-Boot's code issues software reset of the
USB TLL module through the USBTLL_SYSCONFIG. This is the second point of failure for us where CPU execution
is transferred to the "data_abort" exception handler. We were unable to overcome this point of failure at all.
What could be a reason for that?3. Because our board has an external USB PHY which uses ULPI interface we modified U-Boot code to bypass
TLL module reset and and let U-Boot code to perform USB host controller initialization with the assumption
that TLL module is bypassed and thus not needed for our board setup.4. After doing #3(above) U-Boot's code detected USB hub (root hub with 3 ports) but it didn't detect external USB HUB with the ethernet bridge connected to that external hub. We also haven't seen any activity on the HSUSB2_XXX pins with a scope. We checked that correct PIN MUX'ing is in place and it seems to be correct but there are still no activity on HSUSB2_XXX pins.All of the aforementioned make us wonder what is wrong:a. Is it possible for TRM to be incomplete on PIN MUX'ing (we use CUS package)?b. What could be wrong within U-Boot code related with initialization of DPLLs which relate with USB host/TLL module?c. Is there some undocumented feature(s) we might want to use?d. Something else?...Any help would be greatly appreciated.PS: Our external oscillator runs @ 38Mhz (that might help while reading the U-Boot's code).
We selected OMAP3EVM board as the base to start our own board.
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