Re: [PATCH V12 01/12] PCI: Add #defines for some of PCIe spec r4.0 features

Bjorn Helgaas
2019-07-09T14:14:36Z

On Mon, Jul 01, 2019 at 06:09:59PM +0530, Vidya Sagar wrote:
> Add #defines only for the Data Link Feature and Physical Layer 16.0 GT/s
> features.
>
> Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
> Reviewed-by: Thierry Reding <treding@nvidia.com>

Please include spec references in the commit log, e.g., PCIe r5.0, sec
7.7.4, for Data Link Feature and sec 7.7.5 for Physical Layer 16 GT/s.

> include/uapi/linux/pci_regs.h | 22 +++++++++++++++++++++-
> 1 file changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index f28e562d7ca8..1c79f6a097d2 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -713,7 +713,9 @@
> #define PCI_EXT_CAP_ID_DPC 0x1D /* Downstream Port Containment */
> #define PCI_EXT_CAP_ID_L1SS 0x1E /* L1 PM Substates */
> #define PCI_EXT_CAP_ID_PTM 0x1F /* Precision Time Measurement */
> -#define PCI_EXT_CAP_ID_MAX PCI_EXT_CAP_ID_PTM
> +#define PCI_EXT_CAP_ID_DLF 0x25 /* Data Link Feature */
> +#define PCI_EXT_CAP_ID_PL 0x26 /* Physical Layer 16.0 GT/s */

Maybe PCI_EXT_CAP_ID_PL_16GT so there's a little more hint of what
this is for?

> +#define PCI_EXT_CAP_ID_MAX PCI_EXT_CAP_ID_PL
>
> #define PCI_EXT_CAP_DSN_SIZEOF 12
> #define PCI_EXT_CAP_MCAST_ENDPOINT_SIZEOF 40
> @@ -1053,4 +1055,22 @@
> #define PCI_L1SS_CTL1_LTR_L12_TH_SCALE 0xe0000000 /* LTR_L1.2_THRESHOLD_Scale */
> #define PCI_L1SS_CTL2 0x0c /* Control 2 Register */
>
> +/* Data Link Feature */
> +#define PCI_DLF_CAP 0x04 /* Capabilities Register */
> +#define PCI_DLF_LOCAL_DLF_SUP_MASK 0x007fffff /* Local Data Link Feature Supported */
> +#define PCI_DLF_EXCHANGE_ENABLE 0x80000000 /* Data Link Feature Exchange Enable */
> +#define PCI_DLF_STS 0x08 /* Status Register */
> +#define PCI_DLF_REMOTE_DLF_SUP_MASK 0x007fffff /* Remote Data Link Feature Supported */
> +#define PCI_DLF_REMOTE_DLF_SUP_VALID 0x80000000 /* Remote Data Link Feature Support Valid */

I'm a little bit ambivalent about adding #defines that aren't used. I
personally would probably just add the things we use, so the header
file gives a clue about what's currently implemented. But I guess
either way is fine.

> +/* Physical Layer 16.0 GT/s */
> +#define PCI_PL_16GT_CAP 0x04 /* Capabilities Register */
> +#define PCI_PL_16GT_CTRL 0x08 /* Control Register */
> +#define PCI_PL_16GT_STS 0x0c /* Status Register */
> +#define PCI_PL_16GT_LDPM_STS 0x10 /* Local Data Parity Mismatch Status Register */
> +#define PCI_PL_16GT_FRDPM_STS 0x14 /* First Retimer Data Parity Mismatch Status Register */
> +#define PCI_PL_16GT_SRDPM_STS 0x18 /* Second Retimer Data Parity Mismatch Status Register */
> +#define PCI_PL_16GT_RSVD 0x1C /* Reserved */

Use lower-case hex consistently here. There's no global consistency
in this file, but we can at least be consistent in each section. But
I'm even more hesitant about included unused #defines for "reserved"
fields, so if you drop this it would take care of both :)

> +#define PCI_PL_16GT_LE_CTRL 0x20 /* Lane Equalization Control Register */

This is the only register you actually use. You defined a local
PL16G_CAP_OFF_DSP_16G_TX_PRESET_MASK for this register. Shouldn't
that be defined here instead of in
drivers/pci/controller/dwc/pcie-tegra194.c?

> #endif /* LINUX_PCI_REGS_H */
> --
> 2.17.1
>