HI, all.
(please CC to me, I'm not on LKML)

kernel 2.6.25 with ide driver cs5520 does not boot.
Attached part of dmesgs as dmesgs.txt

kernel 2.6.23 with cs5520 is works correct. cs5520 scans ide0 and ide1.
kernel 2.6.24 with cs5520 is works wrong, but it can boot. cs5520 scans ide0 only.
kernel 2.6.25 with cs5520 is works wrong, it cannot boot. 
kernel 2.6.25 with ide-generic(CONFIG_IDE_GENERIC=y) is works correct.

cs5520 of 2.6.24 recognize access mode for hda as DMA. In 2.6.25 as DMA and PIO.
Summaries are:

                  DMA/PIO     ide1              boot
    2.6.18          DMA       found              OK
    2.6.19          pio       found              OK
    2.6.20          pio       found              OK
    2.6.21          pio       found              OK
    2.6.22          pio       found              OK
    2.6.23          pio       found              OK
    2.6.24          DMA       conflict IO ports  OK
    2.6.25      DMA and PIO   found              hang
    2.6.25(ide)    (PIO?)     found              OK

Threre are 2 in timing to hang. When system hangs, The access LED of HDD turning on. 
In addigion, I mind that an access mode is PIO, and it is DMA.

Timing to hangs are:
1:
hda: IC25N030ATCS04-0, ATA DISK drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
hda: max request size: 128KiB
  (system hangs)

2:
hda: IC25N030ATCS04-0, ATA DISK drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
hda: max request size: 128KiB
hda: 58605120 sectors (300005 MB) w/1768KiB Cache, CHS=58140/16/63
hda: cache flushes not supported
  (system hangs)

The pattern 1, I invested with printk() and I guess that system hangs at
  idedisk_setup()
    init_idedisk_capacity()
      idedisk_chech_hpa()
        idedisk_read_native_max_address()
          ide_no_data_taskfile()
            ide_raw_taskfile()
              ide_do_drive_cmd()  <-- did not return


The pattern 2, I guess that
  idedisk_setup()
    write_cache()
     update_ordered()
       blk_queue_ordered()  <-- I confirm reached here