Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v4] PCI: loongson: Use DECLARE_PCI_FIXUP_EARLY for
 bridge_class_quirk()
To:     Tiezhu Yang <yangtiezhu@loongson.cn>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Rob Herring <robh@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Huacai Chen <chenhc@lemote.com>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc:     linux-mips@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org, Xuefeng Li <lixuefeng@loongson.cn>
References: <1595061424-27701-1-git-send-email-yangtiezhu@loongson.cn>
From:   Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Message-ID: <5a173967-098a-9e40-1373-5502506488f4@cogentembedded.com>
Date:   Sat, 18 Jul 2020 11:44:25 +0300
User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <1595061424-27701-1-git-send-email-yangtiezhu@loongson.cn>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 18.07.2020 11:37, Tiezhu Yang wrote:

> According to the datasheet of Loongson LS7A bridge chip, the old version
> of Loongson LS7A PCIE port has a wrong value about PCI class which is
> 0x060000, the correct value should be 0x060400, this bug can be fixed by
> "dev->class = PCI_CLASS_BRIDGE_PCI << 8;" at the software level. As far
> as I know, the latest version of LS7A has already fixed the value at the
> hardware level.
> 
> 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

    "Due to" not needed there.

> EARLY fixup.
> 
> Fixes: 1f58cca5cf2b ("PCI: Add Loongson PCI Controller support")
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
[...]

MBR, Sergei