linux-kernel - Re: [PATCH] NTB: Fix an error in get link status

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Date:   Sun, 17 Nov 2019 18:00:17 -0500
From:   Jon Mason <jdmason@...zu.us>
To:     Jiasen Lin <linjiasen@...on.cn>
Cc:     "S-k, Shyam-sundar" <Shyam-sundar.S-k@....com>,
        Dave Jiang <dave.jiang@...el.com>,
        Allen Hubbe <allenbh@...il.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-ntb <linux-ntb@...glegroups.com>, linjiasen007@...il.com
Subject: Re: [PATCH] NTB: Fix an error in get link status

On Thu, Nov 7, 2019 at 4:37 AM Jiasen Lin <linjiasen@...on.cn> wrote:
>
> The offset of PCIe Capability Header for AMD and HYGON NTB is 0x64,
> but the macro which named "AMD_LINK_STATUS_OFFSET" is defined as 0x68.
> It is offset of Device Capabilities Reg rather than Link Control Reg.
>
> This code trigger an error in get link statsus:
>
>         cat /sys/kernel/debug/ntb_hw_amd/0000:43:00.1/info
>                 LNK STA -               0x8fa1
>                 Link Status -           Up
>                 Link Speed -            PCI-E Gen 0
>                 Link Width -            x0
>
> This patch use pcie_capability_read_dword to get link status.
> After fix this issue, we can get link status accurately:
>
>         cat /sys/kernel/debug/ntb_hw_amd/0000:43:00.1/info
>                 LNK STA -               0x11030042
>                 Link Status -           Up
>                 Link Speed -            PCI-E Gen 3
>                 Link Width -            x16

No response from AMD maintainers, but it looks like you are correct.

This needs a "Fixes:" line here.  I took the liberty of adding one to
this patch.

> Signed-off-by: Jiasen Lin <linjiasen@...on.cn>
> ---
>  drivers/ntb/hw/amd/ntb_hw_amd.c | 5 +++--
>  drivers/ntb/hw/amd/ntb_hw_amd.h | 1 -
>  2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/ntb/hw/amd/ntb_hw_amd.c b/drivers/ntb/hw/amd/ntb_hw_amd.c
> index 156c2a1..ae91105 100644
> --- a/drivers/ntb/hw/amd/ntb_hw_amd.c
> +++ b/drivers/ntb/hw/amd/ntb_hw_amd.c
> @@ -855,8 +855,8 @@ static int amd_poll_link(struct amd_ntb_dev *ndev)
>
>         ndev->cntl_sta = reg;
>
> -       rc = pci_read_config_dword(ndev->ntb.pdev,
> -                                  AMD_LINK_STATUS_OFFSET, &stat);
> +       rc = pcie_capability_read_dword(ndev->ntb.pdev,
> +                                  PCI_EXP_LNKCTL, &stat);
>         if (rc)
>                 return 0;
>         ndev->lnk_sta = stat;
> @@ -1139,6 +1139,7 @@ static const struct ntb_dev_data dev_data[] = {
>  static const struct pci_device_id amd_ntb_pci_tbl[] = {
>         { PCI_VDEVICE(AMD, 0x145b), (kernel_ulong_t)&dev_data[0] },
>         { PCI_VDEVICE(AMD, 0x148b), (kernel_ulong_t)&dev_data[1] },
> +       { PCI_VDEVICE(HYGON, 0x145b), (kernel_ulong_t)&dev_data[0] },

This should be a separate patch.  I took the liberty of splitting it
off into a unique patch and attributing it to you.  I've pushed them
to the ntb-next branch on
https://github.com/jonmason/ntb

Please verify everything looks acceptable to you (given the changes I
did above that are attributed to you).  Also, testing of the latest
code is always appreciated.

Thanks,
Jon


>         { 0, }
>  };
>  MODULE_DEVICE_TABLE(pci, amd_ntb_pci_tbl);
> diff --git a/drivers/ntb/hw/amd/ntb_hw_amd.h b/drivers/ntb/hw/amd/ntb_hw_amd.h
> index 139a307..39e5d18 100644
> --- a/drivers/ntb/hw/amd/ntb_hw_amd.h
> +++ b/drivers/ntb/hw/amd/ntb_hw_amd.h
> @@ -53,7 +53,6 @@
>  #include <linux/pci.h>
>
>  #define AMD_LINK_HB_TIMEOUT    msecs_to_jiffies(1000)
> -#define AMD_LINK_STATUS_OFFSET 0x68
>  #define NTB_LIN_STA_ACTIVE_BIT 0x00000002
>  #define NTB_LNK_STA_SPEED_MASK 0x000F0000
>  #define NTB_LNK_STA_WIDTH_MASK 0x03F00000
> --
> 2.7.4
>
> --
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