Here is the patch, sorry ...
(Enclosed as an attachement because of mailer screwup, I'm away from my
real mail setup right now).
Ben.
On Sat, 2003-01-04 at 10:34, Benjamin Herrenschmidt wrote:
> Hi Alan !
>
> I've needed this patch (well, this is a cleaned up version of what I
> used actually) for some time on PPC and on some embedded platforms. The
> issue that typically happens is when the kernel is booted with an IDE
> device still doing it's POST sequence (or just beeing reset, that is
> with no firmware or a firmware that doesn't wait for the device to be
> ready before booting the kernel).
>
> The patch just waits up to 35 seconds (30 seconds per spec, plus a small
> margin to deal with a couple of bogus drives I saw that took 31 seconds)
> for the BUSY bit to go away on an HWIF.
>
> It's mandatory in the IDE spec to pull-down D7 to ground on an inteface,
> so that an interface with no driver connected should return a value with
> bit BUSY 0x80 cleared, thus will not trigger this wait loop. I did a
> sanity check against 0xff anyway to deal with a couple of bogus
> interfaces I encountered though.
>
> I don't expect this patch to break any existing working configuration,
> so please send to Linus for 2.5. If you accept it, I'll then send a 2.4
> version to Marcelo as well. This have been around for some time and,
> imho, should really get in now.
>
> Regards,
> Ben.
-- Benjamin Herrenschmidt <benh@kernel.crashing.org>
===== drivers/ide/ide-probe.c 1.30 vs edited ===== --- 1.30/drivers/ide/ide-probe.c Mon Dec 2 19:19:20 2002 +++ edited/drivers/ide/ide-probe.c Sat Jan 4 10:37:35 2003 @@ -628,6 +628,68 @@ //EXPORT_SYMBOL(hwif_register); /* + * Code below should be made generic, see comment near call of + * wait_hwif_ready() in probe_hwif() + */ +static int wait_not_busy(ide_hwif_t *hwif, unsigned long timeout) +{ + u8 stat = 0; + + while(timeout--) { + /* Turn this into a schedule() sleep once I'm sure + * about locking issues (2.5 work ?) + */ + mdelay(1); + stat = hwif->INB(hwif->io_ports[IDE_STATUS_OFFSET]); + if ((stat & BUSY_STAT) == 0) + break; + /* Assume a value of 0xff means nothing is connected to + * the interface and it doesn't implement the pull-down + * resistor on D7 + */ + if (stat == 0xff) + break; + } + return ((stat & BUSY_STAT) == 0) ? 0 : -EBUSY; +} + +static int wait_hwif_ready(ide_hwif_t *hwif) +{ + int rc; + + printk("Probing IDE interface %s...\n", hwif->name); + + /* Let HW settle down a bit from whatever init state we + * come from */ + mdelay(2); + + /* Wait for BSY bit to go away, spec timeout is 30 seconds, + * I know of at least one disk who takes 31 seconds, I use 35 + * here to be safe + */ + rc = wait_not_busy(hwif, 35000); + if (rc) + return rc; + + /* Now make sure both master & slave are ready */ + SELECT_DRIVE(&hwif->drives[0]); + hwif->OUTB(8, hwif->io_ports[IDE_CONTROL_OFFSET]); + mdelay(2); + rc = wait_not_busy(hwif, 10000); + if (rc) + return rc; + SELECT_DRIVE(&hwif->drives[1]); + hwif->OUTB(8, hwif->io_ports[IDE_CONTROL_OFFSET]); + mdelay(2); + rc = wait_not_busy(hwif, 10000); + + /* Exit function with master reselected (let's be sane) */ + SELECT_DRIVE(&hwif->drives[0]); + + return rc; +} + +/* * This routine only knows how to look for drive units 0 and 1 * on an interface, so any setting of MAX_DRIVES > 2 won't work here. */ @@ -677,6 +739,29 @@ disable_irq(hwif->irq); local_irq_set(flags); + + /* This is needed on some PPCs and a bunch of BIOS-less embedded + * platforms. Typical cases are: + * + * - The firmware hard reset the disk before booting the kernel, + * the drive is still doing it's poweron-reset sequence, that + * can take up to 30 seconds + * - The firmware does nothing (or no firmware), the device is + * still in POST state (same as above actually). + * - Some CD/DVD/Writer combo drives tend to drive the bus during + * their reset sequence even when they are non-selected slave + * devices, thus preventing discovery of the main HD + * + * Doing this wait-for-busy should not harm any existing configuration + * (at least things won't be worse than what current code does, that + * is blindly go & talk to the drive) and fix some issues like the + * above. + * + * BenH. + */ + if (wait_hwif_ready(hwif)) + printk(KERN_WARNING "%s: Wait for ready failed before probe !\n", hwif->name); + /* * Second drive should only exist if first drive was found, * but a lot of cdrom drives are configured as single slaves.
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