The 82574's blink bit in the LEDCTL register has some challenges when
there is no link, therefore software needs to manually turn on and
off the LED using a timer to make it blink to identify the adapter.
Also the 82574Ls LED_ON mode suffers from the same challenges when there is a lack of link, that's why we needed to add the workaround to properly turn on the LED. With NO link, the LED Invert bit needs to be set to turn the LED on in the 82574L.
We are working on documenting this, so please check later in the year for a new revision of the datasheet and/or the spec update depending on where it lands.
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Then to confirm my sanity or lack thereof, the 82573L works as currently documented and the 82574L doesn't in regard to blink and LED_ON ?
I understood from the 82573L & 82574L docs that blink doesn't work when using the "invert" option but I assume you are saying in addition the 82574L even without the invert being set requires a link to operate ?
So by using the invert to turn on the LED and manually blinking a LED set to the LED_OFF mode the 82573L and 82574L can be handled the same way ?