We were discussing some time ago about IDE drives not waking up from a sleep command, (I.E. hdparm -Y as opposed to a standby, hdparm -y), and this is indeed true at least for a Maxtor drive on my PIIX3 chipset, running 2.4.19.
However, with 2.5.40 it _does_, (eventually, after about 20 seconds), reset the disk. Here is the output of dmesg:
hda: dma_timer_expiry: dma status == 0x21
hda: timeout waiting for DMA
hda: timeout waiting for DMA
hda: (__ide_dma_test_irq) called while not waiting
hda: status timeout: status=0xd0 { Busy }
hda: drive not ready for command
ide0: reset: success
So, this seems to be fixed in the 2.5.X IDE code.
John.