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Subject: Re: [PATCH v3] PCI: loongson: Use DECLARE_PCI_FIXUP_EARLY for
 bridge_class_quirk()
To:     Huacai Chen <chenhc@lemote.com>
References: <1594865946-15188-1-git-send-email-yangtiezhu@loongson.cn>
 <CAAhV-H7_J6oJOYujJqQqm-bpKH-ZKOy3y2yX0TFWzs5ywh=z_g@mail.gmail.com>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Rob Herring <robh@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        "open list:MIPS" <linux-mips@vger.kernel.org>,
        linux-pci@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        Xuefeng Li <lixuefeng@loongson.cn>
From:   Tiezhu Yang <yangtiezhu@loongson.cn>
Message-ID: <86b3d3bb-afd0-85a7-ffc3-959248ec450c@loongson.cn>
Date:   Thu, 16 Jul 2020 10:37:18 +0800
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On 07/16/2020 10:21 AM, Huacai Chen wrote:
> Hi, Tiezhu,
>
> You don't need to use the lower case in the title, "Loongson" is just
> fine (and is recommended).

Hi Huacai,

Thanks for your reply.

In the first version of this patch, I received the following reply by Bjorn:

[Subject line:

   PCI: loongson: Use DECLARE_PCI_FIXUP_EARLY for bridge_class_quirk()

(Driver names are conventionally lower case.)

Lorenzo will probably silently fix this when applying, so this is
mostly just a reminder in case you need to revise this or for future
patches.]

https://lore.kernel.org/patchwork/patch/1254407/

I also checked the git log of drivers/pci/controller:

[yangtiezhu@linux linux.git]$ git log --oneline drivers/pci/controller | 
grep "PCI:" | head
8d7e33d PCI: uniphier: Add Socionext UniPhier Pro5 PCIe endpoint 
controller driver
fcee90c PCI: tegra: Fix runtime PM imbalance on error
3e5095e PCI: vmd: Filter resource type bits from shadow register
1c1dbb2 PCI: tegra194: Fix runtime PM imbalance on error
d0684fd0 PCI: hv: Use struct_size() helper
1f58cca PCI: Add Loongson PCI Controller support
03f8c1b3 PCI: dwc: Use private data pointer of "struct irq_domain" to 
get pcie_port
87dccf0 PCI: amlogic: meson: Don't use FAST_LINK_MODE to set up link
0414b93 PCI: dwc: Fix inner MSI IRQ domain registration
c8a1197 PCI: dwc: pci-dra7xx: Use devm_platform_ioremap_resource_byname()

So use lower case "loongson" may be proper here.

Thanks,
Tiezhu

>
> On Thu, Jul 16, 2020 at 10:19 AM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>> According to the datasheet of Loongson LS7A bridge chip, the old version
>> of Loongson LS7A PCIE port has a hardware bug about PCI class. As far as
>> I know, the latest version has already fixed this bug.
>>
>> In order to maintain downward compatibility, use DECLARE_PCI_FIXUP_EARLY
>> instead of DECLARE_PCI_FIXUP_HEADER for bridge_class_quirk() to fix it as
>> early as possible.
>>
>> Otherwise, in the function pci_setup_device(), the related code about
>> "dev->class" such as "class = dev->class >> 8;" and "dev->transparent
>> = ((dev->class & 0xff) == 1);" maybe get wrong value due to without
>> EARLY fixup.
>>
>> By the way, we can see that the PCI class fixup of other controllers are
>> all EARLY fixups:
>>
>> [root@linux linux.git]# grep -rn -A 3 "PCI_CLASS_BRIDGE_PCI << 8" drivers/pci/controller/ | grep EARLY
>> drivers/pci/controller/pcie-tango.c-327-DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0024, tango_fixup_class);
>> drivers/pci/controller/pcie-tango.c-328-DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0028, tango_fixup_class);
>> drivers/pci/controller/pci-tegra.c-775-DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x0bf0, tegra_pcie_fixup_class);
>> drivers/pci/controller/pci-tegra.c-776-DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x0bf1, tegra_pcie_fixup_class);
>> drivers/pci/controller/dwc/pcie-qcom.c-1442-DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_QCOM, 0x0101, qcom_fixup_class);
>> drivers/pci/controller/dwc/pcie-qcom.c-1443-DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_QCOM, 0x0104, qcom_fixup_class);
>> drivers/pci/controller/pcie-iproc-bcma.c-23-DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_BROADCOM, 0x8011, bcma_pcie2_fixup_class);
>> drivers/pci/controller/pcie-iproc-bcma.c-24-DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_BROADCOM, 0x8012, bcma_pcie2_fixup_class);
>>
>> Fixes: 1f58cca5cf2b ("PCI: Add Loongson PCI Controller support")
>> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
>> ---
>>
>> v2: Modify the patch subject used with lower case "loongson"
>>
>> v3: Update the commit message
>>
>>   drivers/pci/controller/pci-loongson.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/pci/controller/pci-loongson.c b/drivers/pci/controller/pci-loongson.c
>> index 459009c..58b862a 100644
>> --- a/drivers/pci/controller/pci-loongson.c
>> +++ b/drivers/pci/controller/pci-loongson.c
>> @@ -37,11 +37,11 @@ static void bridge_class_quirk(struct pci_dev *dev)
>>   {
>>          dev->class = PCI_CLASS_BRIDGE_PCI << 8;
>>   }
>> -DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LOONGSON,
>> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON,
>>                          DEV_PCIE_PORT_0, bridge_class_quirk);
>> -DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LOONGSON,
>> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON,
>>                          DEV_PCIE_PORT_1, bridge_class_quirk);
>> -DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LOONGSON,
>> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON,
>>                          DEV_PCIE_PORT_2, bridge_class_quirk);
>>
>>   static void system_bus_quirk(struct pci_dev *pdev)
>> --
>> 2.1.0
>>