David McPaul wrote:
2009/4/17 Rob Judd <haiqu@xxxxxxxxxx>:David McPaul wrote:Interestingly my details are similar I wonder if the dma mode is being reported correctly.You should DEFINITELY not be getting 0x00 for the DMA mode there.Ok I have committed a fix to the ide driver and the idestatus and ideinfo commands, the real DMA mode is now reported and includes the theoretical max speed.
I had a nice little side-benefit from this fix of yours.The HDD attached to the secondary bus as slave was still reporting as UDMA mode 2 in `ideinfo` despite being the same type as both drives on the primary bus. So it was being limited to 33MHz.
At first I thought this might be a side-effect of being on the same bus as the DVD-RW drive, but that's ATAPI and anyhow it's very new compared to the HDD. Then the penny dropped.
My secondary bus has a 40-way connecting cable, and those start to have too much cross-talk above 50MHz, so the system was actually downgrading the drive to UDMA mode 2, even though it reports as being capable of UDMA mode 4.
I'll go buy a proper 80-way cable with guard wires tomorrow, and I expect that should fix the problem.
So, thanks. Rob