On Fri, Oct 25, 2019 at 10:00 PM Stuart Hayes <stuart.w.hayes@xxxxxxxxx> wrote:
>
> From: Alexandru Gagniuc <mr.nuke.me@xxxxxxxxx>
>
> The presence detect state (PDS) is normally a logical or of in-band and
> out-of-band presence. As of PCIe 4.0, there is the option to disable
> in-band presence so that the PDS bit always reflects the state of the
> out-of-band presence.
>
> The recommendation of the PCIe spec is to disable in-band presence
> whenever supported.
>
FWIW,
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@xxxxxxxxx>
> ---
> drivers/pci/hotplug/pciehp.h | 1 +
> drivers/pci/hotplug/pciehp_hpc.c | 9 ++++++++-
> include/uapi/linux/pci_regs.h | 2 ++
> 3 files changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
> index 654c972b8ea0..27e4cd6529b0 100644
> --- a/drivers/pci/hotplug/pciehp.h
> +++ b/drivers/pci/hotplug/pciehp.h
> @@ -83,6 +83,7 @@ struct controller {
> struct pcie_device *pcie;
>
> u32 slot_cap; /* capabilities and quirks */
> + unsigned int inband_presence_disabled:1;
>
> u16 slot_ctrl; /* control register access */
> struct mutex ctrl_lock;
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index 1a522c1c4177..dc109d521f30 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -811,7 +811,7 @@ static inline void dbg_ctrl(struct controller *ctrl)
> struct controller *pcie_init(struct pcie_device *dev)
> {
> struct controller *ctrl;
> - u32 slot_cap, link_cap;
> + u32 slot_cap, slot_cap2, link_cap;
> u8 poweron;
> struct pci_dev *pdev = dev->port;
> struct pci_bus *subordinate = pdev->subordinate;
> @@ -869,6 +869,13 @@ struct controller *pcie_init(struct pcie_device *dev)
> FLAG(link_cap, PCI_EXP_LNKCAP_DLLLARC),
> pdev->broken_cmd_compl ? " (with Cmd Compl erratum)" : "");
>
> + pcie_capability_read_dword(pdev, PCI_EXP_SLTCAP2, &slot_cap2);
> + if (slot_cap2 & PCI_EXP_SLTCAP2_IBPD) {
> + pcie_write_cmd_nowait(ctrl, PCI_EXP_SLTCTL_IBPD_DISABLE,
> + PCI_EXP_SLTCTL_IBPD_DISABLE);
> + ctrl->inband_presence_disabled = 1;
> + }
> +
> /*
> * If empty slot's power status is on, turn power off. The IRQ isn't
> * requested yet, so avoid triggering a notification with this command.
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index 29d6e93fd15e..ea1cf9546e4d 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -604,6 +604,7 @@
> #define PCI_EXP_SLTCTL_PWR_OFF 0x0400 /* Power Off */
> #define PCI_EXP_SLTCTL_EIC 0x0800 /* Electromechanical Interlock Control */
> #define PCI_EXP_SLTCTL_DLLSCE 0x1000 /* Data Link Layer State Changed Enable */
> +#define PCI_EXP_SLTCTL_IBPD_DISABLE 0x4000 /* In-band PD disable */
> #define PCI_EXP_SLTSTA 26 /* Slot Status */
> #define PCI_EXP_SLTSTA_ABP 0x0001 /* Attention Button Pressed */
> #define PCI_EXP_SLTSTA_PFD 0x0002 /* Power Fault Detected */
> @@ -676,6 +677,7 @@
> #define PCI_EXP_LNKSTA2 50 /* Link Status 2 */
> #define PCI_CAP_EXP_ENDPOINT_SIZEOF_V2 52 /* v2 endpoints with link end here */
> #define PCI_EXP_SLTCAP2 52 /* Slot Capabilities 2 */
> +#define PCI_EXP_SLTCAP2_IBPD 0x0001 /* In-band PD Disable Supported */
> #define PCI_EXP_SLTCTL2 56 /* Slot Control 2 */
> #define PCI_EXP_SLTSTA2 58 /* Slot Status 2 */
>
> --
> 2.18.1
>
--
With Best Regards,
Andy Shevchenko
