On Tue, Nov 5, 2013 at 11:44 AM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote: > On Tue, Nov 5, 2013 at 6:06 AM, Jiri Kosina <jkosina@xxxxxxx> wrote: >> On Thu, 31 Oct 2013, Bjorn Helgaas wrote: >> >>> > Attached is dmesg output leading to timeouts (that are cured by my >>> > original patch in this thread) and lspci. >>> >>> I opened https://bugzilla.kernel.org/show_bug.cgi?id=64141 for this >>> issue and attached your dmesg log and lspci output. >>> >>> > Please let me know if there is anything else I could do, or if you are >>> > going to proceed with my patch adding the quirk. >>> >>> Your quirk keeps us from disabling MSIs on the device during >>> enumeration. But even if the BIOS left MSIs enabled, there's nothing >>> to field the MSI until after the driver claims the device. So I don't >>> believe this has to be done as a quirk. It should work just as well >>> to do something in the driver when it claims the device. >>> >>> I guess another way to say this is that I don't think we understand >>> what the real problem is, and if we just add a quirk to work around >>> it, we might miss the chance to fix the real problem, and we may never >>> be able to remove the special-case code we're adding in the generic >>> path. >>> >>> I know you said you tried doing something in the driver, and it didn't >>> work. I don't know exactly what you tried, but twa_probe() looks >>> strange to me. The other drivers I looked at do all their PCI >>> initialization before the scsi_host_alloc() / scsi_add_host() / >>> scsi_scan_host() stuff. But twa_probe() has PCI stuff scattered >>> around between those three SCSI calls. In particular, it does the MSI >>> setup way down near the end, after scsi_add_host(), which seems like >>> just the sort of thing that could explain this problem. >> >> What I tried was patch below, but it didn't have any observable effect -- >> the commands sent to the controller would still time out the same way. >> >> Debugging this is not really straightforward for me unfortunately, as I >> don't own the system myself. >> >> I agree that we don't fully understand what is happening, but the quirk >> was the only way I have been able to come up with to make the device >> functioning again (apart from reverting d5dea7d95). >> >> Any other ideas are welcome. > > This patch looks like a good start, but there's a whole lot of other > PCI-related initialization that I would suggest moving as well -- > pci_request_regions(), ioremap(), pci_set_drvdata(), pci_enable_msi, > request_irq(), etc. I would do this myself, but there are some pieces > that don't look completely trivial, e.g., things like > TW_DISABLE_INTERRUPTS() and twa_reset_sequence() don't look like > they're SCSI-specific, but they are currently implemented using > tw_dev, which looks like it's allocated by scsi_host_alloc(). > Untangling all this looks like more work than I want to sign up to. > > But I really don't want to put the quirk in because it's just a quick > hack that apparently just covers up bugs in the driver, and it will be > an annoyance in the PCI core forever. Just FYI, I reassigned https://bugzilla.kernel.org/show_bug.cgi?id=64141 from PCI to SCSI, since I don't think there's a PCI core problem here. I don't know if SCSI pay attention to bugzilla at all; I'm just mentioning it here in case anybody still cares about this problem and was hoping that I was going to do something. Bjorn >> --- >> drivers/scsi/3w-9xxx.c | 10 +++++----- >> 1 files changed, 5 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/scsi/3w-9xxx.c b/drivers/scsi/3w-9xxx.c >> index ba754c3..bad7faf 100644 >> --- a/drivers/scsi/3w-9xxx.c >> +++ b/drivers/scsi/3w-9xxx.c >> @@ -2055,6 +2055,11 @@ static int __devinit twa_probe(struct pci_dev *pdev, const struct pci_device_id >> goto out_disable_device; >> } >> >> + /* Try to enable MSI */ >> + if (use_msi && (pdev->device != PCI_DEVICE_ID_3WARE_9000) && >> + !pci_enable_msi(pdev)) >> + set_bit(TW_USING_MSI, &tw_dev->flags); >> + >> host = scsi_host_alloc(&driver_template, sizeof(TW_Device_Extension)); >> if (!host) { >> TW_PRINTK(host, TW_DRIVER, 0x24, "Failed to allocate memory for device extension"); >> @@ -2134,11 +2139,6 @@ static int __devinit twa_probe(struct pci_dev *pdev, const struct pci_device_id >> le32_to_cpu(*(int *)twa_get_param(tw_dev, 2, TW_INFORMATION_TABLE, >> TW_PARAM_PORTCOUNT, TW_PARAM_PORTCOUNT_LENGTH))); >> >> - /* Try to enable MSI */ >> - if (use_msi && (pdev->device != PCI_DEVICE_ID_3WARE_9000) && >> - !pci_enable_msi(pdev)) >> - set_bit(TW_USING_MSI, &tw_dev->flags); >> - >> /* Now setup the interrupt handler */ >> retval = request_irq(pdev->irq, twa_interrupt, IRQF_SHARED, "3w-9xxx", tw_dev); >> if (retval) { >> >> >> -- >> Jiri Kosina >> SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
