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CPSW In-Band Operating Mode of RGMII question...

Joe Cossette
Intellectual 780 points

In the current 8148 TRM (14 Oct 2011) in section 8.2.1.7.3.3 In-Band Mode of Operation it indicates that setting the EXT_EN bit in the MACCONTROL sliver register (bit 18) enables this operating mode as defined in the RGMII specification.

But in reviewing the currently released Linux source code from "DM814x Linux PSP - 04.01.00.06.patch2" (released in EZSDK v5.03), in the file cpsw.c (under drivers/net), in function _cpsw_adjust_link(), on line 729 this feature is specifically disabled for all speeds, but on line 733  bit 18 is only getting enabled for 10-base speeds.  Unless I missed it somewhere else in the Linux codebase, I see nowhere else is this feature enabled.

I see in prior Linux driver releases that this code is new to the current release.  Is the omission of this feature from the other link speeds intentional?  Is there some problem when enabling this feature for speeds other than 10-base?

  • 0
    TI__Intellectual 2750 points

    Joe Cossette

    Mac control module has capability of working either in 1g or in 10/100 mbps, we can choose either 1g speed or 100mbps speed only. There is no other way to choose 10 mbps speed when gigabit enable bit is disable in force mode of operation - it always works in 100 mbps. So, in order to work in 10 mbps speed, we need to set bit18 (in band mode). When in band mode is enabled, clk from phy is taken care and conneted as 10mbps. Of course we can enable in band mode for other speed also (1G/100mbps) where clk will be provided by phy, we have not tested this.

    with regards

    Mugunthan V N

  • 0 in reply to Mugunthan V N
    TI__Intellectual 1750 points

    Will in band mode be tested and verified for 100 and 1G? If so, when will this be scheduled?

    Thanks,

    Tim