On Wed, Feb 21, 2007 at 09:40:10PM +0900, Tejun Heo wrote: > Hello, Gary. > > Gary Hade wrote: > > I instrumented the code and found that for the SATA hard drive BSY was set > > just before the call to ahci_init_port() from ahci_port_start() and clear > > after the return from ahci_init_port(). For the GoVault BSY was still set > > after the return from ahci_init_port() and remained set for almost 2 seconds. > > > > The below patch which gives BSY some extra time to clear repairs the problem. > > Unlike the extra delay for ata-piix needed by GoVault I believe this delay > > will only be seen for attached devices that need it. Please let me know > > what you think. > > Can you post full dmesg without the patch? And which controller are you > using (lspci -nn please)? How come it doesn't support CLO? > > I don't think the patch is a good idea. !BSY wait before reset is > supposed to be done in ->prereset() if possible. ahci skips that step > because waiting for !BSY isn't reliable after hotplug and it often > wastes 30secs for no good reason after an hotplug event. > > Even if you need to add that specific shorter wait, the correct place > would be ->prereset() not at the end of ->port_start(). > > I don't think fixing here and there for GoVault drive is a good idea. > It's not gonna be tested widely and GoValut would end up working on some > controllers while broken on others. I think recently posted EH > improvements and faster reset patches should help here. The first reset > will fail timely and all in all the drive should be detected in slightly > over ten secs, which isn't that bad and actually is okay if parallel > probing is implemented. > > I dunno. Maybe the correct thing to do is wait briefly for !BSY in > std_prereset() when SKIP_D2H_BSY is set. Tejun, I will be on vacation for a few days (returning 3/1) so I thought I would go ahead and provide the below patch before you have had a chance to review the information I sent you yesterday and actually confirm that it still looks like a viable solution. Thanks, Gary -- Gary Hade System x Enablement IBM Linux Technology Center 503-578-4503 IBM T/L: 775-4503 garyhade@xxxxxxxxxx http://www.ibm.com/linux/ltc We encountered a problem where the BSY status bit is still set on entry to the 'ahci' error handler during initialization of the Quantum GoVault when attached to an ICH6R/ICH6RW controller. This caused a software reset failure due to failed BSY/DRQ check in ahci_softreset() forcing a hard reset with the following messages logged. ata1: softreset failed (port busy but CLO unavailable) ata1: softreset failed, retrying in 5 secs ata1: port is slow to respond, please be patient (Status 0x80) ata1: port failed to respond (30 secs, Status 0x80) ata1: COMRESET failed (device not ready) ata1: hardreset failed, retrying in 5 secs It was taking almost 2 seconds for BSY to clear following the return from ahci_init_port() in ahci_port_start() so this patch gives BSY up to 3 seconds extra time to clear during prereset eliminating the problem. Signed-off-by: Gary Hade <garyhade@xxxxxxxxxx> --- linux-2.6.20-rc7/drivers/ata/libata-core.c.orig 2007-02-22 11:52:34.000000000 -0800 +++ linux-2.6.20-rc7/drivers/ata/libata-core.c 2007-02-22 14:59:44.000000000 -0800 @@ -2915,6 +2915,8 @@ int ata_std_prereset(struct ata_port *ap struct ata_eh_context *ehc = &ap->eh_context; const unsigned long *timing = sata_ehc_deb_timing(ehc); int rc; + u8 status; + unsigned long timeout; /* handle link resume & hotplug spinup */ if ((ehc->i.flags & ATA_EHI_RESUME_LINK) && @@ -2942,9 +2944,19 @@ int ata_std_prereset(struct ata_port *ap /* Wait for !BSY if the controller can wait for the first D2H * Reg FIS and we don't know that no device is attached. + * For other controllers a brief wait (up to 3 secs) may be + * needed for some devices. */ if (!(ap->flags & ATA_FLAG_SKIP_D2H_BSY) && !ata_port_offline(ap)) ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT); + else { + timeout = jiffies + 3*HZ; + status = ata_busy_wait(ap, ATA_BUSY, 300); + while ((status & ATA_BUSY) && time_before(jiffies, timeout)) { + msleep(50); + status = ata_busy_wait(ap, ATA_BUSY, 3); + } + } return 0; } - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
