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While I have not seen an AM335x+TLK110 design yet, I do not see a problem in EMAC booting from such a solution as long as a couple of caveats are understood and addressed beforehand.
The ROM code in AM335x expects that the PHY will come up in Auto-Negotiate mode. For TLK110, please refer to Table 3-1 of the TLK110 datasheet to strap the AN_EN, AN_1, and AN_0 pins accordingly. As an aside, this table appear to have an error. In the second section it references "Forced Mode" for the relevant pins as all having boot time value of '1', when in fact this should be 'Auto-Negotiate' with advertised capabilities of 10/100 Half&Full.
The output clock (CLKOUT) of the TLK110 device cannot be used to source the RMII clock to AM335x as doing so would violate the interface timing. Instead, a shared CMOS-level oscillator source would be needed for both MAC and PHY. Please see Figure 4-2 of the TLK datasheet for more details.
While all interface timings should be understood and addressed as part of any board design, pay particular attention to the RMII interface should this interface be chosen as it is fairly sensitive to timing issues due to it's relatively high operating frequency.
Thanks for replying. And for the useful information.
Though, I don't see the first issue you mention in the current datasheet. Table 3.1 with AN pins 1 1 1 gives "advertised mode".
Do you also know if the TLK110 updates the speed selection bit in Basic Mode Control Register (8.1.1 in the datasheet)? (since that how the boot rom code determines the speed, see Advisory 1.0.7 in silicon errata for am335x)
Advisory 1.0.7 only applies to silicon revision 1.0.
The ROM code was updated in silicon revision 2.0 to read the Auto-Negotiation Advertisement and Auto-Negotiation Link Base Page Ability registers to determine the link speed.
This detail was not included in the latest AM335x Silicon Errata. Silicon revision 2.0 will be removed from Advisory 1.0.7 in the next errata update.
The original question only applies if you plan to use silicon revision 1.0 with the TLK110.
I did note that silicon rev 2.0 does not have the speed register issue. (Though when I posted the original question rev 2.0 was not listed at all). However, I do not know which revision we'll be using for the first round of boards, and it would be helpful to know if TLK110 would work anyway.
So the remaining question is whether TLK110 updates its speed settings register. (Or do you recommend moving that question to another part of the forum?).
I don't work on that project anymore. But if I remember correctly, our design was changed to boot another way. So we never tried to do EMAC boot via TLK110. I don't know if it would work or not.
