[+cc Libor (thanks for the ping!)] On Fri, Oct 25, 2019 at 03:00:44PM -0400, Stuart Hayes wrote: > In older PCIe specs, PDS (presence detect) would come up when the > "in-band" presence detect pin connected, and would be up before DLLLA > (link active). > > In PCIe 4.0 (as an ECN) and in PCIe 5.0, there is a new bit to show if > in-band presence detection can be disabled for the slot, and another bit > that disables it--and a recommendation that it should be disabled if it > can be. In addition, certain OEMs disable in-band presence detection > without implementing these bits. > > This means it is possible to get a "card present" interrupt after the > link is up and the driver is loaded. This causes an erroneous removal > of the device driver, followed by an immediate re-probing. > > This patch set defines these new bits, uses them to disable in-band > presence detection if it can be, waits for PDS to go up if in-band > presence detection is disabled, and adds a DMI table that will let us > know if we should assume in-band presence is disabled on a system. > > The first two patches in this set come from a patch set that was > submitted but not accepted many months ago by Alexandru Gagniuc [1]. > The first is unmodified, the second has the commit message and timeout > modified. > > [1] https://patchwork.kernel.org/cover/10909167/ > [v3,0/4] PCI: pciehp: Do not turn off slot if presence comes up after link > > v2: > - modify loop in pcie_wait_for_presence to do..while > > v3: > - remove unused variable declaration > - modify text of warning message > > v4: > - remove "!!" boolean conversion in an "if" condition for readability > - add explanation comment in dmi table > > Alexandru Gagniuc (2): > PCI: pciehp: Add support for disabling in-band presence > PCI: pciehp: Wait for PDS if in-band presence is disabled > > Stuart Hayes (1): > PCI: pciehp: Add dmi table for in-band presence disabled > > drivers/pci/hotplug/pciehp.h | 1 + > drivers/pci/hotplug/pciehp_hpc.c | 50 +++++++++++++++++++++++++++++++- > include/uapi/linux/pci_regs.h | 2 ++ > 3 files changed, 52 insertions(+), 1 deletion(-) I added the spec reference to the 1/3 commit log, tried to make the tweaks Lukas suggested (interdiff below), used ctrl_info() instead of pci_info() (I would actually like to change the whole driver to use pci_info(), but better to be consistent for now), and applied to pci/hotplug for v5.7. Somebody should also update lspci to: - Do something with DevCap AttnBtn, AttnInd, PwrInd to indicate that they were only defined for PCIe r1.0 and have been explicitly undefined since then. If there's a way to identify those 1.0 devices and only decode those fields for 1.0, that would be nice. - Add SltCap2 and SltCtrl2 decoding. Speak up if you plan to do this so we don't duplicate effort. Bjorn diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c index ae0108b92084..469873b44a8e 100644 --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -284,7 +284,7 @@ static void pcie_wait_for_presence(struct pci_dev *pdev) timeout -= 10; } while (timeout > 0); - pci_info(pdev, "Timeout waiting for Presence Detect state to be set\n"); + ctrl_info(ctrl, "Timeout waiting for Presence Detect\n"); } int pciehp_check_link_status(struct controller *ctrl) @@ -921,6 +921,16 @@ struct controller *pcie_init(struct pcie_device *dev) ctrl->state = list_empty(&subordinate->devices) ? OFF_STATE : ON_STATE; up_read(&pci_bus_sem); + 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 (dmi_first_match(inband_presence_disabled_dmi_table)) + ctrl->inband_presence_disabled = 1; + /* Check if Data Link Layer Link Active Reporting is implemented */ pcie_capability_read_dword(pdev, PCI_EXP_LNKCAP, &link_cap); @@ -930,7 +940,7 @@ struct controller *pcie_init(struct pcie_device *dev) PCI_EXP_SLTSTA_MRLSC | PCI_EXP_SLTSTA_CC | PCI_EXP_SLTSTA_DLLSC | PCI_EXP_SLTSTA_PDC); - ctrl_info(ctrl, "Slot #%d AttnBtn%c PwrCtrl%c MRL%c AttnInd%c PwrInd%c HotPlug%c Surprise%c Interlock%c NoCompl%c LLActRep%c%s\n", + ctrl_info(ctrl, "Slot #%d AttnBtn%c PwrCtrl%c MRL%c AttnInd%c PwrInd%c HotPlug%c Surprise%c Interlock%c NoCompl%c IbPresDis%c LLActRep%c%s\n", (slot_cap & PCI_EXP_SLTCAP_PSN) >> 19, FLAG(slot_cap, PCI_EXP_SLTCAP_ABP), FLAG(slot_cap, PCI_EXP_SLTCAP_PCP), @@ -941,19 +951,10 @@ struct controller *pcie_init(struct pcie_device *dev) FLAG(slot_cap, PCI_EXP_SLTCAP_HPS), FLAG(slot_cap, PCI_EXP_SLTCAP_EIP), FLAG(slot_cap, PCI_EXP_SLTCAP_NCCS), + ctrl->inband_presence_disabled, 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 (dmi_first_match(inband_presence_disabled_dmi_table)) - 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 b464d2f76513..f9701410d3b5 100644 --- a/include/uapi/linux/pci_regs.h +++ b/include/uapi/linux/pci_regs.h @@ -681,7 +681,7 @@ #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_SLTCAP2_IBPD 0x00000001 /* In-band PD Disable Supported */ #define PCI_EXP_SLTCTL2 56 /* Slot Control 2 */ #define PCI_EXP_SLTSTA2 58 /* Slot Status 2 */
