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

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Date:   Wed, 20 Nov 2019 17:52:42 +0800
From:   Jiasen Lin <linjiasen@...on.cn>
To:     Jon Mason <jdmason@...zu.us>
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>,
        Jiasen Lin <linjiasen@...on.cn>
Subject: Re: [PATCH] NTB: Fix an error in get link status



On 2019/11/18 18:17, Jiasen Lin wrote:
> 
> 
> On 2019/11/18 7:00, Jon Mason wrote:
>> 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.
>>
> 
> Thank you for your suggestions. Yes, this patch fix the commit id: 
> a1b3695 ("NTB: Add support for AMD PCI-Express Non-Transparent Bridge").
> 
>>> 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
>>
> Thank you for your comment. We appreciate the time and effort you have 
> spent to split it off, I will test it ASAP.
> 
>> 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
>>

I have tested these patches that are pushed to ntb-next branch, they 
work well on HYGON platforms.

Thanks,
Jiasen Lin

>>
>>>          { 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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>>>
> 
> Thanks,
> 
> Jiasen Lin