Re: [PATCH] PCI: add quirk for 3ware 9650SE controller

From: Bjorn Helgaas
Date: Tue Jun 03 2014 - 19:01:17 EST

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 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 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.


>> ---
>> 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,
>> - /* 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
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