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 );
SET_REG(ATA_CONTROL, CONTROL_nIEN|CONTROL_SRST );
sleep(1); /* >= 5us */ <-- *** HANGS HERE ***
SET_REG(ATA_CONTROL, CONTROL_nIEN);
sleep(1); /* >2ms */
lcd_log("sleep #2 done");
/* This little sucker can take up to 30 seconds */
retry_count = 8;
do
{
lcd_log("boing");
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
