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

From: Jiasen Lin
Date: Wed Nov 20 2019 - 04:57:19 EST



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@xxxxxxxx> 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:

ÂÂÂÂÂÂÂÂ cat /sys/kernel/debug/ntb_hw_amd/0000:43:00.1/info
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ LNK STA -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ 0x8fa1
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ Link Status -ÂÂÂÂÂÂÂÂÂÂ Up
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ Link Speed -ÂÂÂÂÂÂÂÂÂÂÂ PCI-E Gen 0
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ Link Width -ÂÂÂÂÂÂÂÂÂÂÂ x0

This patch use pcie_capability_read_dword to get link status.
After fix this issue, we can get link status accurately:

ÂÂÂÂÂÂÂÂ cat /sys/kernel/debug/ntb_hw_amd/0000:43:00.1/info
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ LNK STA -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ 0x11030042
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ Link Status -ÂÂÂÂÂÂÂÂÂÂ Up
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ Link Speed -ÂÂÂÂÂÂÂÂÂÂÂ PCI-E Gen 3
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ Link Width -ÂÂÂÂÂÂÂÂÂÂÂ 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@xxxxxxxx>
---
 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)

ÂÂÂÂÂÂÂÂ ndev->cntl_sta = reg;

-ÂÂÂÂÂÂ rc = pci_read_config_dword(ndev->ntb.pdev,
-ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ AMD_LINK_STATUS_OFFSET, &stat);
+ÂÂÂÂÂÂ rc = pcie_capability_read_dword(ndev->ntb.pdev,
+ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ PCI_EXP_LNKCTL, &stat);
ÂÂÂÂÂÂÂÂ if (rc)
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ return 0;
ÂÂÂÂÂÂÂÂ 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[] = {
ÂÂÂÂÂÂÂÂ { PCI_VDEVICE(AMD, 0x145b), (kernel_ulong_t)&dev_data[0] },
ÂÂÂÂÂÂÂÂ { PCI_VDEVICE(AMD, 0x148b), (kernel_ulong_t)&dev_data[1] },
+ÂÂÂÂÂÂ { 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


ÂÂÂÂÂÂÂÂ { 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