On Thursday 08 February 2018 02:24 PM, Niklas Cassel wrote:
> On 16/11/17 13:26, Vignesh R wrote:
>> +linux-pci
>>
>> Hi Chris,
>>
>> On Thursday 16 November 2017 05:20 PM, Quadros, Roger wrote:
>>> +Vignesh
>>>
>>> On 13/09/17 17:26, Chris Welch wrote:
>>>> We are developing a product based on the TI AM5728 EVM. The product
>>>> utilizes a TUSB7340 PCIe USB host for additional ports. The TUSB7340 is
>>>> detected and setup properly and works OK with low data rate devices.
>>>> However, hot plugging a Realtek USB network adapter and doing Ethernet
>>>> transfer bandwidth testing using iperf3 causes the TUSB7340 host to be
>>>> locked out. The TUSB7340 host appears to no longer communicate and the
>>>> logging indicates xhci_hcd 0000:01:00.0: HC died; cleaning up. Same issue
>>>> occurs with another USB Ethernet adapter I tried (Asus).
>>>>
>>>> We looked at using another host and found a mini PCIe card that utilizes
>>>> the µPD720201 and can be directly installed on the TI AM5728 EVM. The
>>>> card is detected properly and we reran the transfer test. The uPD720201
>>>> gets locks out with the same problem.
>>>>
>>>> The AM5728 testing was performed using the TI SD card stock
>>>> am57xx-evm-linux-04.00.00.04.img, kernel am57xx-evm 4.9.28-geed43d1050,
>>>> and it reports that it is using the TI AM572x EVM Rev A3 device tree.
>>>>
>>>> It shows the following logging when it fails (this is with the TI EVM and
>>>> uPD720201).
>>>>
>>>> [ 630.400899] xhci_hcd 0000:01:00.0: xHCI host not responding to stop
>>>> endpoint command.
>>>> [ 630.408769] xhci_hcd 0000:01:00.0: Assuming host is dying, halting host.
>>>> [ 630.420849] r8152 2-4:1.0 enp1s0u4: Tx status -108
>>>> [ 630.425667] r8152 2-4:1.0 enp1s0u4: Tx status -108
>>>> [ 630.430483] r8152 2-4:1.0 enp1s0u4: Tx status -108
>>>> [ 630.435297] r8152 2-4:1.0 enp1s0u4: Tx status -108
>>>> [ 630.440122] xhci_hcd 0000:01:00.0: HC died; cleaning up
>>>> [ 630.453961] usb 2-4: USB disconnect, device number 2
>>>>
>>>> The problem appears to be a general driver issue given we get the same
>>>> problem with both the TUSB7340 and the µPD720201.
>>
>> Seems like PCIe driver is missing MSI IRQs leading to stall.
>> Reading xHCI registers via PCIe mem space confirms this.
>>
>> I see two problems wrt MSI handling:
>> Since commit 8c934095fa2f3 ("PCI: dwc: Clear MSI interrupt status after it
>> is handled, not before"),
>> dwc clears MSI status after calling EP's IRQ handler. But, it happens that
>> another MSI interrupt is
>> raised just at the end of EP's IRQ handler and before clearing MSI status.
>> This will result in loss of new MSI IRQ as we clear the MSI IRQ status
>> without handling.
>>
>> Another problem appears to be wrt dra7xx PCIe wrapper:
>> PCIECTRL_DRA7XX_CONF_IRQSTATUS_MSI does not seem to catch MSI IRQs unless,
>> its ensured that PCIE_MSI_INTR0_STATUS register read returns 0.
>>
>> So, could you try reverting commit 8c934095fa2f3 and
>> also apply below patch and let me know if that fixes the issue?
>
> Hello Vignesh,
>
> It is not only dra7xx that is affected by this bug,
> all other DWC based drivers as well.
>
> I suggest that we either:
> Revert 8c934095fa2f ("PCI: dwc: Clear MSI interrupt status after it is
> handled,
> not before")
I will send a revert soon.
> or
> You implement a generic solution
> (i.e. in drivers/pci/dwc/pcie-designware-host.c)
> rather than just a dra7xx specific solution.
Reverting 8c934095fa2f should unblock all other DWC drivers. For dra7xx,
I will send separate patches to fix TI dra7xx specific wrapper level IRQ
handler.
>> -----------
>>
>> diff --git a/drivers/pci/dwc/pci-dra7xx.c b/drivers/pci/dwc/pci-dra7xx.c
>> index e77a4ceed74c..8280abc56f30 100644
>> --- a/drivers/pci/dwc/pci-dra7xx.c
>> +++ b/drivers/pci/dwc/pci-dra7xx.c
>> @@ -259,10 +259,17 @@ static irqreturn_t dra7xx_pcie_msi_irq_handler(int
>> irq, void *arg)
>> u32 reg;
>>
>> reg = dra7xx_pcie_readl(dra7xx, PCIECTRL_DRA7XX_CONF_IRQSTATUS_MSI);
>> + dra7xx_pcie_writel(dra7xx, PCIECTRL_DRA7XX_CONF_IRQSTATUS_MSI, reg);
>>
>> switch (reg) {
>> case MSI:
>> - dw_handle_msi_irq(pp);
>> + /*
>> + * Need to make sure no MSI IRQs are pending before
>> + * exiting handler, else the wrapper will not catch new
>> + * IRQs. So loop around till dw_handle_msi_irq() returns
>> + * IRQ_NONE
>> + */
>> + while (dw_handle_msi_irq(pp) != IRQ_NONE);
>> break;
>> case INTA:
>> case INTB:
>> @@ -273,8 +280,6 @@ static irqreturn_t dra7xx_pcie_msi_irq_handler(int irq,
>> void *arg)
>> break;
>> }
>>
>> - dra7xx_pcie_writel(dra7xx, PCIECTRL_DRA7XX_CONF_IRQSTATUS_MSI, reg);
>> -
>> return IRQ_HANDLED;
>> }
>>
>>
>>
>>
--
Regards
Vignesh
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