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Subject: bootloader hanging early on 80G G5.5 iPod - debugging attempt

bootloader hanging early on 80G G5.5 iPod - debugging attempt

From: Paul Collins <>
Date: Wed, 11 Oct 2006 21:39:24 +1300

A number of people have succeeded in running Rockbox on their 30G G5.5
iPods with some trickery: a regular bootloader and rockbox build,
modified ipod_fw, a fresh 512bps filesystem, and an extra partition
table entry for Rockbox's benefit, with the start and count multiplied
by four. However, when I try the same technique on my 80G iPod, I
find that the bootloader hangs while trying to read the MBR.

amiconn suggested that I try to debug ATA init somehow, but there
doesn't seem to be much to it. The value of the IDE control register
is 0x20150020 - does that sound right?

ata_device_init() (see firmware/target/arm/ata-pp5020.c) does

    outl(inl(0xc3000028) | (1 << 5), 0xc3000028);
    outl(inl(0xc3000028) & ~0x10000000, 0xc3000028);

but that just writes back the register twice, unchanged, because
neither of the bitwise operations alter any of the register's bits.

This next bit is probably a waste of time if the ATA init is indeed
the problem, but I got a nice tour through the Rockbox code on the
way, so I don't mind.

By adding a bunch of debugging messages, I traced the hang through the
following call chain:

[bootloader] main()
        -> disk_init()
                -> ata_read_sectors() (it's reading the MBR)
                        -> copy_read_sectors
                        status & STATUS_ERR is true
                        -> perform_soft_reset() - which hangs

perform_soft_reset() hangs here:

  static int perform_soft_reset(void)
      int ret;
      int retry_count;

      SET_REG(ATA_SELECT, SELECT_LBA | ata_device );
      sleep(1); /* >= 5us */ <-- *** HANGS HERE ***

      sleep(1); /* >2ms */
      lcd_log("sleep #2 done");

      /* This little sucker can take up to 30 seconds */
      retry_count = 8;
          ret = wait_for_rdy();
      } while(!ret && retry_count--);

      /* Massage the return code so it is 0 on success and -1 on failure */
      ret = ret?0:-1;

      return ret;

So that's a bit odd.

I removed all of my LCD-writing calls from ata_read_sectors() on down,
leaving just two: one before and one after that first sleep(1) call,
and that seems to definitely be where it hangs - I see the before
message, and not the after message.

Suggestions for more stuff to try are welcome.

Paul Collins
Wellington, New Zealand
Dag vijandelijk luchtschip de huismeester is dood
Received on 2006-10-11

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