Jeff Garzik wrote: ..
Further -- someone with a long ATA memory correct me -- I think that we can increase ATA_MAX_PRD beyond 256. Most DMA engines should just keep chugging along, provided that we continue to respect the 64k IDE DMA boundaries.
MAX_PRD used to be equal to MAX_SECTORS, as that's the worst case scenario. The only real gotcha I remember from the original IDE driver, was that some (very few) controllers were buggy with handing of a sector_count of zero (256), so setting the limit to a slightly lower value prevented that from ever being a problem. That was in the days before the block layer could limit the segment count. I don't remember which chipsets had the bug; TRM290 was one, but that never really worked well anyway, and nobody other than myself seemed to have one of those cards. Mmm.. Possibly the Pacific Digital ADMA-100 here as well.. I can look that one up if I can find the old box full of cards/docs.. Cheers - : 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
