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

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Date:   Mon, 18 Nov 2019 18:17:38 +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>
Subject: Re: [PATCH] NTB: Fix an error in get link status



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
> 
> 
>>          { 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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>> To view this discussion on the web visit https://groups.google.com/d/msgid/linux-ntb/1573119336-107732-1-git-send-email-linjiasen%40hygon.cn.

Thanks,

Jiasen Lin