Hello. Alan Cox wrote:
On Llu, 2006-05-15 at 19:12 +0400, Sergei Shtylyov wrote:
For PIO2+ actually, according to Intel's PRM (29860004.pdf), and it's said to have no effect in the lower modes. This is actually not very correct since when one issues Set Transfer Mode ATA command with the value (8 + PIOn), this means select PIO _flow control_ mode n, so -IORDY is assumed to be in use.
PIO2 depends on the drive (there is a drive parameter telling you the highest timing clock you can do with/without IORDY
Yes. But when you're setting any _explicit_ PIO mode with Set Features command, you're tell the drive to use -IORDY at the same time.
I'm also not clear if the "no MWDMA0" list has been updated correctly for the newer chipsets.
What is/was the point for keeping MW DMA 0 support anyway? On PIIX, it's greatly slowed down (600 vs 480 ns cycle) and was never "offically" supported by Intel.
Some old old drives only do MWDMA0. The Intel docs I have here don't describe it in any way as "unsupported",
They just don't describe it, period. :-)
merely broken on some ICH variants.
ICH errata #55: "Note that DMA Mode-0 is an unsupported mode of the ICH."
Alan
MBR, Sergei - : 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
