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SubjectRe: [PATCH v2] pci: loongson: Workaround MIPS firmware MRRS settings
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在 2023/8/29 20:26, Linux regression tracking (Thorsten Leemhuis) 写道:
> Hi, Thorsten here, the Linux kernel's regression tracker. Top-posting
> for once, to make this easily accessible to everyone.
>
> What's the status here? From my point it looks like this regression that
> was ported six weeks ago is still not fixed -- and it seems nothing has
> happened since three weeks now. But maybe I'm just missing something,
> that's why I'm asking.

Hi Thorsten,

Thanks for reaching back, unfortunately there is no progress so far.

+ Huacai, what's your opinion here? I do think this fix is in best shape for
now.

Thanks
- Jiaxun

>
> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
> --
> Everything you wanna know about Linux kernel regression tracking:
> https://linux-regtracking.leemhuis.info/about/#tldr
> If I did something stupid, please tell me, as explained on that page.
>
> #regzbot poke
>
> On 08.08.23 09:38, Jiaxun Yang wrote:
>>
>> 在 2023/8/6 22:30, Huacai Chen 写道:
>>> Hi, Jiaxun,
>>>
>>> On Sun, Aug 6, 2023 at 10:20 AM Jiaxun Yang <jiaxun.yang@flygoat.com>
>>> wrote:
>>>>
>>>> 在 2023/7/25 14:10, Jiaxun Yang 写道:
>>>>> This is a partial revert of commit 8b3517f88ff2 ("PCI:
>>>>> loongson: Prevent LS7A MRRS increases") for MIPS based Loongson.
>>>>>
>>>>> There are many MIPS based Loongson systems in wild that
>>>>> shipped with firmware which does not set maximum MRRS properly.
>>>>>
>>>>> Limiting MRRS to 256 for all as MIPS Loongson comes with higher
>>>>> MRRS support is considered rare.
>>>>>
>>>>> Cc: stable@vger.kernel.org
>>>>> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217680
>>>>> Fixes: 8b3517f88ff2 ("PCI: loongson: Prevent LS7A MRRS increases")
>>>>> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
>>>> Ping?
>>>> I expect this patch to go through PCI fixes tree.
>>> Can we do it like this by modifying the existing loongson_mrrs_quirk()?
>> Hmm, I'm not sure this will work, since loongson_mrrs_quirk only run on
>> bridges
>> but the old quirk should run on every single device.
>>
>> Thanks
>> Jiaxun
>>
>>> static void loongson_mrrs_quirk(struct pci_dev *pdev)
>>> {
>>>          /*
>>>           * Some Loongson PCIe ports have h/w limitations of maximum read
>>>           * request size. They can't handle anything larger than this. So
>>>           * force this limit on any devices attached under these ports.
>>>           */
>>>          struct pci_host_bridge *bridge =
>>> pci_find_host_bridge(pdev->bus);
>>>
>>> #ifdef CONFIG_MIPS
>>>          set_pcie_ports_to_mrrs_256_to_emulate_the_firmware_behavior();
>>> #endif
>>>
>>>          bridge->no_inc_mrrs = 1;
>>> }
>>>
>>>> Thanks
>>>> - Jiaxun
>>>>
>>>>> ---
>>>>> v2: Rename quirk name to: loongson_old_mrrs_quirk
>>>>> ---
>>>>>    drivers/pci/controller/pci-loongson.c | 38
>>>>> +++++++++++++++++++++++++++
>>>>>    1 file changed, 38 insertions(+)
>>>>>
>>>>> diff --git a/drivers/pci/controller/pci-loongson.c
>>>>> b/drivers/pci/controller/pci-loongson.c
>>>>> index fe0f732f6e43..d0f68b102d10 100644
>>>>> --- a/drivers/pci/controller/pci-loongson.c
>>>>> +++ b/drivers/pci/controller/pci-loongson.c
>>>>> @@ -108,6 +108,44 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON,
>>>>>    DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON,
>>>>>                        DEV_LS7A_PCIE_PORT6, loongson_mrrs_quirk);
>>>>>
>>>>> +#ifdef CONFIG_MIPS
>>>>> +static void loongson_old_mrrs_quirk(struct pci_dev *pdev)
>>>>> +{
>>>>> +     struct pci_bus *bus = pdev->bus;
>>>>> +     struct pci_dev *bridge;
>>>>> +     static const struct pci_device_id bridge_devids[] = {
>>>>> +             { PCI_VDEVICE(LOONGSON, DEV_LS2K_PCIE_PORT0) },
>>>>> +             { PCI_VDEVICE(LOONGSON, DEV_LS7A_PCIE_PORT0) },
>>>>> +             { PCI_VDEVICE(LOONGSON, DEV_LS7A_PCIE_PORT1) },
>>>>> +             { PCI_VDEVICE(LOONGSON, DEV_LS7A_PCIE_PORT2) },
>>>>> +             { PCI_VDEVICE(LOONGSON, DEV_LS7A_PCIE_PORT3) },
>>>>> +             { PCI_VDEVICE(LOONGSON, DEV_LS7A_PCIE_PORT4) },
>>>>> +             { PCI_VDEVICE(LOONGSON, DEV_LS7A_PCIE_PORT5) },
>>>>> +             { PCI_VDEVICE(LOONGSON, DEV_LS7A_PCIE_PORT6) },
>>>>> +             { 0, },
>>>>> +     };
>>>>> +
>>>>> +     /* look for the matching bridge */
>>>>> +     while (!pci_is_root_bus(bus)) {
>>>>> +             bridge = bus->self;
>>>>> +             bus = bus->parent;
>>>>> +             /*
>>>>> +              * There are still some wild MIPS Loongson firmware won't
>>>>> +              * set MRRS properly. Limiting MRRS to 256 as MIPS
>>>>> Loongson
>>>>> +              * comes with higher MRRS support is considered rare.
>>>>> +              */
>>>>> +             if (pci_match_id(bridge_devids, bridge)) {
>>>>> +                     if (pcie_get_readrq(pdev) > 256) {
>>>>> +                             pci_info(pdev, "limiting MRRS to 256\n");
>>>>> +                             pcie_set_readrq(pdev, 256);
>>>>> +                     }
>>>>> +                     break;
>>>>> +             }
>>>>> +     }
>>>>> +}
>>>>> +DECLARE_PCI_FIXUP_ENABLE(PCI_ANY_ID, PCI_ANY_ID,
>>>>> loongson_old_mrrs_quirk);
>>>>> +#endif
>>>>> +
>>>>>    static void loongson_pci_pin_quirk(struct pci_dev *pdev)
>>>>>    {
>>>>>        pdev->pin = 1 + (PCI_FUNC(pdev->devfn) & 3);

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