Robert Hancock wrote: ..
From some of the traces I took previously (posted on LKML as "sata_nv ADMA controller lockup investigation" way back in Feb 07), what seems to occur is that when the second command is issued very rapidly (within less than 20 microseconds, or potentially longer) after the previous command's completion, the ADMA status changes from 0x500 (STOPPED and IDLE) to 0x400 (just IDLE) as it typically does, but then it sticks there, no interrupt is ever raised, and CPB response flags remain at 0.
.. Assuming that NVidia got their ADMA core logic from Pacific Digital (the inventors), then it may have some of the same bugs as the original. One of those bugs is that the aGO trigger is sampled in a "racey" way, such that it sometimes may miss a recent addition to the ring. The *only* way to guarantee things with the original Pacific Digital core was to (1) always retrigger aGO for a full ring scan with each new addition, and (2) poll periodically (every half second or so) rather than relying exclusively on the IRQ actually working.. Dunno about the NVidia version. Cheers - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
