linux-kernel - Re: [PATCH] PCI: designware-ep: Fix the Header Type check

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Date:   Fri, 14 Aug 2020 09:50:52 -0600
From:   Rob Herring <robh@...nel.org>
To:     Zhiqiang Hou <Zhiqiang.Hou@....com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        PCI <linux-pci@...r.kernel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Andrew Murray <amurray@...goodpenguin.co.uk>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>
Subject: Re: [PATCH] PCI: designware-ep: Fix the Header Type check

On Fri, Aug 14, 2020 at 2:15 AM Zhiqiang Hou <Zhiqiang.Hou@....com> wrote:
>
> From: Hou Zhiqiang <Zhiqiang.Hou@....com>
>
> The current check will result in the multiple function device
> fails to initialize. So fix the check by masking out the
> multiple function bit.
>
> Fixes: 0b24134f7888 ("PCI: dwc: Add validation that PCIe core is set to correct mode")
> Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@....com>
> ---
>  drivers/pci/controller/dwc/pcie-designware-ep.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index 4680a51c49c0..4b7abfb1e669 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -654,7 +654,7 @@ int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
>         int i;
>
>         hdr_type = dw_pcie_readb_dbi(pci, PCI_HEADER_TYPE);
> -       if (hdr_type != PCI_HEADER_TYPE_NORMAL) {
> +       if (hdr_type & 0x7f != PCI_HEADER_TYPE_NORMAL) {

Should have () around 'hdr_type & 0x7f'.

>                 dev_err(pci->dev,
>                         "PCIe controller is not set to EP mode (hdr_type:0x%x)!\n",
>                         hdr_type);

However, shouldn't the printed value be masked too? I'd just do:

hdr_type = dw_pcie_readb_dbi(pci, PCI_HEADER_TYPE) & 0x7f;

Perhaps add a #define too. '0x7f' is used in several places.

Rob