linux-kernel - Re: [PATCH v2] PCI: loongson: Use DECLARE_PCI_FIXUP_EARLY for bridge_class

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Date:   Wed, 15 Jul 2020 10:36:36 +0800
From:   Tiezhu Yang <yangtiezhu@...ngson.cn>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Rob Herring <robh@...nel.org>, Huacai Chen <chenhc@...ote.com>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        linux-mips@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, Xuefeng Li <lixuefeng@...ngson.cn>
Subject: Re: [PATCH v2] PCI: loongson: Use DECLARE_PCI_FIXUP_EARLY for
 bridge_class_quirk()

On 07/14/2020 11:08 PM, Lorenzo Pieralisi wrote:
> On Tue, Jul 14, 2020 at 03:37:51PM +0800, Tiezhu Yang wrote:
>> On 06/12/2020 09:30 AM, Tiezhu Yang wrote:
>>> Use DECLARE_PCI_FIXUP_EARLY instead of DECLARE_PCI_FIXUP_HEADER
>>> for bridge_class_quirk() in pci-loongson.c, otherwise the fixup
>>> has no effect.
>>>
>>> Fixes: 1f58cca5cf2b ("PCI: Add Loongson PCI Controller support")
>>> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
>>> ---
>>>
>>> v2:
>>>     - modify the patch subject used with lower case "loongson"
>>>
>>> This patch is based on mips-next tree.
>>>
>>>    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)
>> Hi,
>>
>> Any comments?

Hi Lorenzo,

Thanks for your reply.

> (1) how was this driver tested if this patch is required ? Is it because
>      you are testing on a different platform ?

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.
I test it on the old version which has hardware bug.

> (2) Please explain why it is needed (I mean describe what happens
>      in current code and how this fixes it) in the commit log, it is
>      useful for people who may need to tweak this code further

OK, this patch is to maintain downward compatibility, I will add
more info to the commit message and then send v3.

Thanks,
Tiezhu

>
> I will apply it then, thanks.
>
> Lorenzo
>
>> Could you please apply this patch?
>>
>> Thanks,
>> Tiezhu
>>