Barry Upshaw

MCF54455EVB BSP ATA Question

Discussion created by Barry Upshaw on Jan 11, 2008
Latest reply on Jan 11, 2008 by Barry Upshaw
Thanks to kmahan (and others?) for the new BSP with ATA support!!!
As described in the known issues, DMA isn't working for this port, and transfers are MODE 4 PIO, which results in pretty poor performance (see below).
It is noted that DMA will be supported in a future release.  The project I'm working on (custom board) will be transferring image data from an ATA drive, so I'd like to get the best performance possible.
1) Is "hdparm -t" reasonably accurate in reporting performance?
2) What kind of increase might we expect when DMA MODE 5 is supported?
Thanks again for getting this working!
Some stats:
/mnt # hdparm -T /dev/sda
 Timing buffer-cache reads:   128 MB in  8.07 seconds = 15.86 MB/sec
/mnt # hdparm -t /dev/sda
 Timing buffered disk reads:  64 MB in 21.33 seconds =  3.00 MB/sec
/mnt # hdparm -t /dev/sda1
 Timing buffered disk reads:  64 MB in 35.02 seconds =  1.83 MB/sec
/mnt # hdparm -T /dev/sda1

My PC Core-Duo2 Fedora8 system (I know, not really comparable - running SATA-300, UDMA with much more memory, >20x CPU performance) - but for reference:

 Timing buffered disk reads:  164 MB in  3.03 seconds =  54.16 MB/sec
 Timing buffered disk reads:  230 MB in  3.02 seconds =  76.12 MB/sec