linux-kernel - Re: [PATCH] PCI: iproc: Set all 24 bits of PCI class code

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Message-ID: <CAGQAs7xHpfftf4=_zyhdJhRHaN-P3BaY+n1NQ-ED8cFRJ1+EAA@mail.gmail.com>
Date:   Wed, 5 Jan 2022 08:57:09 -0800
From:   Roman Bacik <roman.bacik@...adcom.com>
To:     Pali Rohár <pali@...nel.org>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        bcm-kernel-feedback-list@...adcom.com, linux-pci@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: iproc: Set all 24 bits of PCI class code

On Wed, Jan 5, 2022 at 1:36 AM Pali Rohár <pali@...nel.org> wrote:
>
> Register 0x43c in its low 24 bits contains PCI class code.
>
> Update code to set all 24 bits of PCI class code and not only upper 16 bits
> of PCI class code.
>
> Use a new macro PCI_CLASS_BRIDGE_PCI_NORMAL which represents whole 24 bits
> of normal PCI bridge class.
>
> Signed-off-by: Pali Rohár <pali@...nel.org>
>
> ---
> Roman helped me with this change and confirmed that class code is stored
> really in bits [23:0] of custom register 0x43c (normally class code is
> stored in bits [31:8] of pci register 0x08).
>
> This patch depends on patch which adds PCI_CLASS_BRIDGE_PCI_NORMAL macro:
> https://lore.kernel.org/linux-pci/20211220145140.31898-1-pali@kernel.org/
> ---
>  drivers/pci/controller/pcie-iproc.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/pci/controller/pcie-iproc.c b/drivers/pci/controller/pcie-iproc.c
> index 3df4ab209253..2519201b0e51 100644
> --- a/drivers/pci/controller/pcie-iproc.c
> +++ b/drivers/pci/controller/pcie-iproc.c
> @@ -789,14 +789,13 @@ static int iproc_pcie_check_link(struct iproc_pcie *pcie)
>                 return -EFAULT;
>         }
>
> -       /* force class to PCI_CLASS_BRIDGE_PCI (0x0604) */
> +       /* force class to PCI_CLASS_BRIDGE_PCI_NORMAL (0x060400) */
>  #define PCI_BRIDGE_CTRL_REG_OFFSET     0x43c
> -#define PCI_CLASS_BRIDGE_MASK          0xffff00
> -#define PCI_CLASS_BRIDGE_SHIFT         8
> +#define PCI_BRIDGE_CTRL_REG_CLASS_MASK 0xffffff
>         iproc_pci_raw_config_read32(pcie, 0, PCI_BRIDGE_CTRL_REG_OFFSET,
>                                     4, &class);
> -       class &= ~PCI_CLASS_BRIDGE_MASK;
> -       class |= (PCI_CLASS_BRIDGE_PCI << PCI_CLASS_BRIDGE_SHIFT);
> +       class &= ~PCI_BRIDGE_CTRL_REG_CLASS_MASK;
> +       class |= PCI_CLASS_BRIDGE_PCI_NORMAL;
>         iproc_pci_raw_config_write32(pcie, 0, PCI_BRIDGE_CTRL_REG_OFFSET,
>                                      4, class);
>
> --
> 2.20.1
>

Acked-by: Roman Bacik <roman.bacik@...adcom.com>

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