Patchwork PCI: add PCIe 8.0 GT/s supported link speed define

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Submitter Betty Dall
Date Nov. 20, 2012, 6:58 p.m.
Message ID <1353437939-29210-1-git-send-email-betty.dall@hp.com>
Download mbox | patch
Permalink /patch/200379/
State Changes Requested
Headers show

Comments

Betty Dall - Nov. 20, 2012, 6:58 p.m.
Add a new define for the 8.0 GT/s supported link speed added in the PCI
3.0 specification.  This is used to identify a device's current link speed
(PCI_EXP_CLS).

Here is the section of the PCI 3.0 specification:
"Supported Link Speeds Vector – This field indicates the
supported Link speed(s) of the associated Port. For each bit, a
value of 1b indicates that the corresponding Link speed is
supported; otherwise, the Link speed is not supported.
Bit definitions within this field are:
Bit 0 2.5 GT/s
Bit 1 5.0 GT/s
Bit 2 8.0 GT/s
Bits 6:3 RsvdP
Multi-Function devices associated with an Upstream Port must
report the same value in this field for all Functions."

Signed-off-by: Betty Dall <betty.dall@hp.com>
---
 include/uapi/linux/pci_regs.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
Yijing Wang - Nov. 22, 2012, 1:54 a.m.
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index 20ae747..0cf8abb 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -469,6 +469,7 @@
>  #define  PCI_EXP_LNKSTA_CLS	0x000f	/* Current Link Speed */
>  #define  PCI_EXP_LNKSTA_CLS_2_5GB 0x01	/* Current Link Speed 2.5GT/s */
>  #define  PCI_EXP_LNKSTA_CLS_5_0GB 0x02	/* Current Link Speed 5.0GT/s */
> +#define  PCI_EXP_LNKSTA_CLS_8_0GB 0x04	/* Current Link Speed 8.0GT/s */
>  #define  PCI_EXP_LNKSTA_NLW	0x03f0	/* Nogotiated Link Width */
>  #define  PCI_EXP_LNKSTA_NLW_SHIFT 4	/* start of NLW mask in link status */
>  #define  PCI_EXP_LNKSTA_LT	0x0800	/* Link Training */
> 

Hi Betty,
   There is another patch uses this PCI_EXP_LNKSTA_CLS_8_0GB ? I think maybe move this change to
the patch uses this symbol is better.
Bjorn Helgaas - Dec. 5, 2012, midnight
On Tue, Nov 20, 2012 at 11:58 AM, Betty Dall <betty.dall@hp.com> wrote:
> Add a new define for the 8.0 GT/s supported link speed added in the PCI
> 3.0 specification.  This is used to identify a device's current link speed
> (PCI_EXP_CLS).
>
> Here is the section of the PCI 3.0 specification:
> "Supported Link Speeds Vector – This field indicates the
> supported Link speed(s) of the associated Port. For each bit, a
> value of 1b indicates that the corresponding Link speed is
> supported; otherwise, the Link speed is not supported.
> Bit definitions within this field are:
> Bit 0 2.5 GT/s
> Bit 1 5.0 GT/s
> Bit 2 8.0 GT/s
> Bits 6:3 RsvdP
> Multi-Function devices associated with an Upstream Port must
> report the same value in this field for all Functions."
>
> Signed-off-by: Betty Dall <betty.dall@hp.com>
> ---
>  include/uapi/linux/pci_regs.h |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index 20ae747..0cf8abb 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -469,6 +469,7 @@
>  #define  PCI_EXP_LNKSTA_CLS    0x000f  /* Current Link Speed */
>  #define  PCI_EXP_LNKSTA_CLS_2_5GB 0x01 /* Current Link Speed 2.5GT/s */
>  #define  PCI_EXP_LNKSTA_CLS_5_0GB 0x02 /* Current Link Speed 5.0GT/s */
> +#define  PCI_EXP_LNKSTA_CLS_8_0GB 0x04 /* Current Link Speed 8.0GT/s */

This isn't right, is it?  The Link Status Current Link Speed field is
a four-bit field that's encoded.  The currently defined values are 1-7
(not 1, 2, 4, 8).  So I think you would want to add this instead:

#define  PCI_EXP_LNKSTA_CLS_8_0GB 0x03 /* Current Link Speed 8.0GT/s */

That corresponds to bit 2 in the Supported Link Speeds Vector in the
Link Capabilities 2 register:

#define  PCI_EXP_LNKCAP2_SLS_8_0GB 0x04 /* Supported Link Speed 8.0GT/s */

This whole mess looks like potential off-by-one errors everywhere, and
I could be mistaken about this :)

While you're here, can you fix the typo ("Nogotiated") in the line below?

>  #define  PCI_EXP_LNKSTA_NLW    0x03f0  /* Nogotiated Link Width */
>  #define  PCI_EXP_LNKSTA_NLW_SHIFT 4    /* start of NLW mask in link status */
>  #define  PCI_EXP_LNKSTA_LT     0x0800  /* Link Training */
> --
> 1.7.7.6
>
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Patch

diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index 20ae747..0cf8abb 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -469,6 +469,7 @@ 
 #define  PCI_EXP_LNKSTA_CLS	0x000f	/* Current Link Speed */
 #define  PCI_EXP_LNKSTA_CLS_2_5GB 0x01	/* Current Link Speed 2.5GT/s */
 #define  PCI_EXP_LNKSTA_CLS_5_0GB 0x02	/* Current Link Speed 5.0GT/s */
+#define  PCI_EXP_LNKSTA_CLS_8_0GB 0x04	/* Current Link Speed 8.0GT/s */
 #define  PCI_EXP_LNKSTA_NLW	0x03f0	/* Nogotiated Link Width */
 #define  PCI_EXP_LNKSTA_NLW_SHIFT 4	/* start of NLW mask in link status */
 #define  PCI_EXP_LNKSTA_LT	0x0800	/* Link Training */