| Message ID | 20231011123451.34827-1-s-vadapalli@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | PCI: keystone: Don't enable BAR0 if link is not detected | expand |
Hi Siddharth, On Wed, Oct 11, 2023 at 06:04:51PM +0530, Siddharth Vadapalli wrote: > Since the function dw_pcie_host_init() ignores the absence of link under > the assumption that link can come up later, it is possible that the > pci_host_probe(bridge) function is invoked even when no endpoint device > is connected. In such a situation, the ks_pcie_v3_65_add_bus() function > configures BAR0 when the link is not up, resulting in Completion Timeouts > during the MSI configuration performed later by the PCI Express Port driver > to setup AER, PME and other services. Thus, leave BAR0 disabled if link is > not yet detected when the ks_pcie_v3_65_add_bus() function is invoked. I'm trying to make sense of this. In this path: pci_host_probe pci_scan_root_bus_bridge pci_register_host_bridge bus = pci_alloc_bus(NULL) # root bus bus->ops->add_bus(bus) ks_pcie_v3_65_add_bus The BAR0 in question must belong to a Root Port. And it sounds like the issue must be related to MSI-X, since the original MSI doesn't involve any BARs. I don't understand why the Root Port's BAR0 is related to the link being up. MSI-X configuration of the Root Port (presumably using BAR0) shouldn't involve any transactions to devices *below* the Root Port, and I would expect that BAR to be available (readable and writable) regardless of whether the link is up. If we skip the BAR0 configuration because the link is down at the time of pci_host_probe(), when *do* we do that configuration? I don't see another path to ks_pcie_v3_65_add_bus() for the root bus later. Do you know what exactly causes the Completion Timeout? Is this a read to BAR0, or some attempted access to a downstream device, or something else? Keystone is the only driver that uses .add_bus() for this, so it seems a little weird, but maybe this is related to some Keystone-specific hardware design. > Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com> > --- > > Hello, > > This patch is based on linux-next tagged next-20231011. > > Regards, > Siddharth. > > drivers/pci/controller/dwc/pci-keystone.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c > index 49aea6ce3e87..ac2ad112d616 100644 > --- a/drivers/pci/controller/dwc/pci-keystone.c > +++ b/drivers/pci/controller/dwc/pci-keystone.c > @@ -459,7 +459,8 @@ static int ks_pcie_v3_65_add_bus(struct pci_bus *bus) > struct dw_pcie *pci = to_dw_pcie_from_pp(pp); > struct keystone_pcie *ks_pcie = to_keystone_pcie(pci); > > - if (!pci_is_root_bus(bus)) > + /* Don't enable BAR0 if link is not yet up at this point */ > + if (!pci_is_root_bus(bus) || !dw_pcie_link_up(pci)) > return 0; > > /* Configure and set up BAR0 */ > -- > 2.34.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Hello Bjorn, Thank you for reviewing the patch. On 11/10/23 19:16, Bjorn Helgaas wrote: > Hi Siddharth, > > On Wed, Oct 11, 2023 at 06:04:51PM +0530, Siddharth Vadapalli wrote: >> Since the function dw_pcie_host_init() ignores the absence of link under >> the assumption that link can come up later, it is possible that the >> pci_host_probe(bridge) function is invoked even when no endpoint device >> is connected. In such a situation, the ks_pcie_v3_65_add_bus() function >> configures BAR0 when the link is not up, resulting in Completion Timeouts >> during the MSI configuration performed later by the PCI Express Port driver >> to setup AER, PME and other services. Thus, leave BAR0 disabled if link is >> not yet detected when the ks_pcie_v3_65_add_bus() function is invoked. > > I'm trying to make sense of this. In this path: > > pci_host_probe > pci_scan_root_bus_bridge > pci_register_host_bridge > bus = pci_alloc_bus(NULL) # root bus > bus->ops->add_bus(bus) > ks_pcie_v3_65_add_bus > > The BAR0 in question must belong to a Root Port. And it sounds like > the issue must be related to MSI-X, since the original MSI doesn't > involve any BARs. Yes, the issue is related to MSI-X. I will list down the exact set of function calls below as well as the place where the completion timeout first occurs: ks_pcie_probe dw_pcie_host_init pci_host_probe pci_bus_add_devices pci_bus_add_device device_attach __device_attach bus_for_each_drv __device_attach_driver (invoked using fn(drv, data)) driver_probe_device __driver_probe_device really_probe pci_device_probe pcie_portdrv_probe pcie_port_device_register pcie_init_service_irqs pcie_port_enable_irq_vec pci_alloc_irq_vectors pci_alloc_irq_vectors_affinity __pci_enable_msix_range msix_capability_init msix_setup_interrupts msix_setup_msi_descs msix_prepare_msi_desc In this function: msix_prepare_msi_desc, the following readl() causes completion timeout: desc->pci.msix_ctrl = readl(addr + PCI_MSIX_ENTRY_VECTOR_CTRL); The completion timeout with the readl is only observed when the link is down (No Endpoint device is actually connected to the PCIe connector slot). The symptoms of the above completion timeout show up as a 45 second delay during boot if no Endpoint device is connected. This 45 second delay is due to the fact that each readl() which normally takes 4 milliseconds (in presence of Endpoint device) now take around 40 milliseconds due to waiting for completion. Also, if I disable Completion Timeout in the PCIe controller, Linux hangs at the readl() mentioned above. That is the very first readl() causing the completion timeout. > > I don't understand why the Root Port's BAR0 is related to the link > being up. MSI-X configuration of the Root Port (presumably using > BAR0) shouldn't involve any transactions to devices *below* the Root > Port, and I would expect that BAR to be available (readable and > writable) regardless of whether the link is up. > > If we skip the BAR0 configuration because the link is down at the time > of pci_host_probe(), when *do* we do that configuration? I don't see > another path to ks_pcie_v3_65_add_bus() for the root bus later. > > Do you know what exactly causes the Completion Timeout? Is this a > read to BAR0, or some attempted access to a downstream device, or > something else? > > Keystone is the only driver that uses .add_bus() for this, so it seems > a little weird, but maybe this is related to some Keystone-specific > hardware design. Yes, I am not fully sure myself why BAR0 being enabled is causing the issue. I will debug further within the function ks_pcie_v3_65_add_bus() to see which section of it causes issues when the Link is down. What I am certain of however is that exiting the ks_pcie_v3_65_add_bus() function if Link is down fixes the completion timeouts observed above with the readl(), thereby making the 45 second delay vanish during boot when no endpoint device is connected. Please let me know in case of any suggestions to fix this issue. > >> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com> >> --- >> >> Hello, >> >> This patch is based on linux-next tagged next-20231011. >> >> Regards, >> Siddharth. >> >> drivers/pci/controller/dwc/pci-keystone.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c >> index 49aea6ce3e87..ac2ad112d616 100644 >> --- a/drivers/pci/controller/dwc/pci-keystone.c >> +++ b/drivers/pci/controller/dwc/pci-keystone.c >> @@ -459,7 +459,8 @@ static int ks_pcie_v3_65_add_bus(struct pci_bus *bus) >> struct dw_pcie *pci = to_dw_pcie_from_pp(pp); >> struct keystone_pcie *ks_pcie = to_keystone_pcie(pci); >> >> - if (!pci_is_root_bus(bus)) >> + /* Don't enable BAR0 if link is not yet up at this point */ >> + if (!pci_is_root_bus(bus) || !dw_pcie_link_up(pci)) >> return 0; >> >> /* Configure and set up BAR0 */ >> -- >> 2.34.1 >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
On Thu, Oct 12, 2023 at 10:15:09AM +0530, Siddharth Vadapalli wrote: > Hello Bjorn, > > Thank you for reviewing the patch. > > On 11/10/23 19:16, Bjorn Helgaas wrote: > > Hi Siddharth, > > > > On Wed, Oct 11, 2023 at 06:04:51PM +0530, Siddharth Vadapalli wrote: > >> Since the function dw_pcie_host_init() ignores the absence of link under > >> the assumption that link can come up later, it is possible that the > >> pci_host_probe(bridge) function is invoked even when no endpoint device > >> is connected. In such a situation, the ks_pcie_v3_65_add_bus() function > >> configures BAR0 when the link is not up, resulting in Completion Timeouts > >> during the MSI configuration performed later by the PCI Express Port driver > >> to setup AER, PME and other services. Thus, leave BAR0 disabled if link is > >> not yet detected when the ks_pcie_v3_65_add_bus() function is invoked. > > > > I'm trying to make sense of this. In this path: > > > > pci_host_probe > > pci_scan_root_bus_bridge > > pci_register_host_bridge > > bus = pci_alloc_bus(NULL) # root bus > > bus->ops->add_bus(bus) > > ks_pcie_v3_65_add_bus > > > > The BAR0 in question must belong to a Root Port. And it sounds like > > the issue must be related to MSI-X, since the original MSI doesn't > > involve any BARs. > > Yes, the issue is related to MSI-X. I will list down the exact set of function > calls below as well as the place where the completion timeout first occurs: > ks_pcie_probe > dw_pcie_host_init > pci_host_probe > pci_bus_add_devices > pci_bus_add_device > device_attach > __device_attach > bus_for_each_drv > __device_attach_driver (invoked using fn(drv, data)) > driver_probe_device > __driver_probe_device > really_probe > pci_device_probe > pcie_portdrv_probe > pcie_port_device_register > pcie_init_service_irqs > pcie_port_enable_irq_vec > pci_alloc_irq_vectors > pci_alloc_irq_vectors_affinity > __pci_enable_msix_range > msix_capability_init > msix_setup_interrupts > msix_setup_msi_descs > msix_prepare_msi_desc > In this function: msix_prepare_msi_desc, the following readl() > causes completion timeout: > desc->pci.msix_ctrl = readl(addr + PCI_MSIX_ENTRY_VECTOR_CTRL); > The completion timeout with the readl is only observed when the link > is down (No Endpoint device is actually connected to the PCIe > connector slot). Do you know the address ("addr")? From pci_msix_desc_addr(), it looks like it should be: desc->pci.mask_base + desc->msi_index * PCI_MSIX_ENTRY_SIZE and desc->pci.mask_base should be dev->msix_base, which we got from msix_map_region(), which ioremaps part of the BAR indicated by the MSI-X Table Offset/Table BIR register. I wonder if this readl() is being handled as an MMIO access to a downstream device instead of a Root Port BAR access because it's inside the Root Port's MMIO window. Could you dump out these values just before the readl()? phys_addr inside msix_map_region() dev->msix_base desc->pci.mask_base desc->msi_index addr call early_dump_pci_device() on the Root Port Bjorn
On 12/10/23 22:13, Bjorn Helgaas wrote: > On Thu, Oct 12, 2023 at 10:15:09AM +0530, Siddharth Vadapalli wrote: >> Hello Bjorn, >> >> Thank you for reviewing the patch. >> >> On 11/10/23 19:16, Bjorn Helgaas wrote: >>> Hi Siddharth, >>> ... >> msix_prepare_msi_desc >> In this function: msix_prepare_msi_desc, the following readl() >> causes completion timeout: >> desc->pci.msix_ctrl = readl(addr + PCI_MSIX_ENTRY_VECTOR_CTRL); >> The completion timeout with the readl is only observed when the link >> is down (No Endpoint device is actually connected to the PCIe >> connector slot). > > Do you know the address ("addr")? From pci_msix_desc_addr(), it looks > like it should be: > > desc->pci.mask_base + desc->msi_index * PCI_MSIX_ENTRY_SIZE > > and desc->pci.mask_base should be dev->msix_base, which we got from > msix_map_region(), which ioremaps part of the BAR indicated by the > MSI-X Table Offset/Table BIR register. > > I wonder if this readl() is being handled as an MMIO access to a > downstream device instead of a Root Port BAR access because it's > inside the Root Port's MMIO window. > > Could you dump out these values just before the readl()? > > phys_addr inside msix_map_region() > dev->msix_base > desc->pci.mask_base > desc->msi_index > addr phys_addr: 0x10102000 msix_base: 0xffff80000997a000 mask_base: 0xffff80000997a000 msi_index: 0 addr: 0xffff80000997a000 Also, the details of BAR allocation from the logs are: keystone-pcie 5500000.pcie: host bridge /bus@100000/pcie@5500000 ranges: keystone-pcie 5500000.pcie: IO 0x0010020000..0x001002ffff -> 0x0000000000 keystone-pcie 5500000.pcie: MEM 0x0010030000..0x0017ffffff -> 0x0010030000 keystone-pcie 5500000.pcie: iATU unroll: enabled keystone-pcie 5500000.pcie: iATU regions: 8 ob, 8 ib, align 64K, limit 4G keystone-pcie 5500000.pcie: Phy link never came up keystone-pcie 5500000.pcie: PCI host bridge to bus 0000:00 pci_bus 0000:00: root bus resource [bus 00-ff] pci_bus 0000:00: root bus resource [io 0x0000-0xffff] pci_bus 0000:00: root bus resource [mem 0x10030000-0x17ffffff] pci 0000:00:00.0: [104c:b00c] type 01 class 0x060400 pci 0000:00:00.0: reg 0x10: [mem 0x05500000-0x055fffff] pci 0000:00:00.0: reg 0x38: [mem 0x00000000-0x0000ffff pref] pci 0000:00:00.0: supports D1 pci 0000:00:00.0: PME# supported from D0 D1 D3hot pci 0000:00:00.0: BAR 0: assigned [mem 0x10100000-0x101fffff] pci 0000:00:00.0: BAR 6: assigned [mem 0x10030000-0x1003ffff pref] pci 0000:00:00.0: PCI bridge to [bus 01-ff] The value of phys_addr lies within the range allocated to BAR0. > call early_dump_pci_device() on the Root Port I invoked early_dump_pci_device() within the pci_setup_device() function in drivers/pci/probe.c and the output is: pci 0000:00:00.0: config space: 00000000: 4c 10 0c b0 07 01 10 00 01 00 04 06 00 00 01 00 00000010: 00 00 50 05 00 00 00 00 00 01 ff 00 00 00 00 00 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00000030: 00 00 00 00 40 00 00 00 00 00 00 00 ff 01 00 00 00000040: 01 50 c3 5b 08 00 00 00 00 00 00 00 00 00 00 00 00000050: 05 70 80 01 00 00 00 00 00 00 00 00 00 00 00 00 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00000070: 10 b0 42 00 01 80 00 00 10 20 00 00 22 3c 73 00 00000080: 00 00 11 10 00 00 00 00 c0 03 40 00 00 00 01 00 00000090: 00 00 00 00 1f 04 00 00 00 00 00 00 06 00 00 00 000000a0: 02 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 000000b0: 11 00 00 01 00 20 00 00 00 40 00 00 00 00 00 00 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > Bjorn
On 13/10/23 10:33, Siddharth Vadapalli wrote: > > > On 12/10/23 22:13, Bjorn Helgaas wrote: >> On Thu, Oct 12, 2023 at 10:15:09AM +0530, Siddharth Vadapalli wrote: >>> Hello Bjorn, >>> >>> Thank you for reviewing the patch. >>> >>> On 11/10/23 19:16, Bjorn Helgaas wrote: >>>> Hi Siddharth, >>>> > > ... > >>> msix_prepare_msi_desc >>> In this function: msix_prepare_msi_desc, the following readl() >>> causes completion timeout: >>> desc->pci.msix_ctrl = readl(addr + PCI_MSIX_ENTRY_VECTOR_CTRL); >>> The completion timeout with the readl is only observed when the link >>> is down (No Endpoint device is actually connected to the PCIe >>> connector slot). >> >> Do you know the address ("addr")? From pci_msix_desc_addr(), it looks >> like it should be: >> >> desc->pci.mask_base + desc->msi_index * PCI_MSIX_ENTRY_SIZE >> >> and desc->pci.mask_base should be dev->msix_base, which we got from >> msix_map_region(), which ioremaps part of the BAR indicated by the >> MSI-X Table Offset/Table BIR register. >> >> I wonder if this readl() is being handled as an MMIO access to a >> downstream device instead of a Root Port BAR access because it's >> inside the Root Port's MMIO window. >> >> Could you dump out these values just before the readl()? >> >> phys_addr inside msix_map_region() >> dev->msix_base >> desc->pci.mask_base >> desc->msi_index >> addr > > phys_addr: 0x10102000 > msix_base: 0xffff80000997a000 > mask_base: 0xffff80000997a000 > msi_index: 0 > addr: 0xffff80000997a000 > > Also, the details of BAR allocation from the logs are: > keystone-pcie 5500000.pcie: host bridge /bus@100000/pcie@5500000 ranges: > keystone-pcie 5500000.pcie: IO 0x0010020000..0x001002ffff -> 0x0000000000 > keystone-pcie 5500000.pcie: MEM 0x0010030000..0x0017ffffff -> 0x0010030000 > keystone-pcie 5500000.pcie: iATU unroll: enabled > keystone-pcie 5500000.pcie: iATU regions: 8 ob, 8 ib, align 64K, limit 4G > keystone-pcie 5500000.pcie: Phy link never came up > keystone-pcie 5500000.pcie: PCI host bridge to bus 0000:00 > pci_bus 0000:00: root bus resource [bus 00-ff] > pci_bus 0000:00: root bus resource [io 0x0000-0xffff] > pci_bus 0000:00: root bus resource [mem 0x10030000-0x17ffffff] > pci 0000:00:00.0: [104c:b00c] type 01 class 0x060400 > pci 0000:00:00.0: reg 0x10: [mem 0x05500000-0x055fffff] > pci 0000:00:00.0: reg 0x38: [mem 0x00000000-0x0000ffff pref] > pci 0000:00:00.0: supports D1 > pci 0000:00:00.0: PME# supported from D0 D1 D3hot > pci 0000:00:00.0: BAR 0: assigned [mem 0x10100000-0x101fffff] > pci 0000:00:00.0: BAR 6: assigned [mem 0x10030000-0x1003ffff pref] > pci 0000:00:00.0: PCI bridge to [bus 01-ff] > > The value of phys_addr lies within the range allocated to BAR0. > >> call early_dump_pci_device() on the Root Port > > I invoked early_dump_pci_device() within the pci_setup_device() function in > drivers/pci/probe.c and the output is: > > pci 0000:00:00.0: config space: > 00000000: 4c 10 0c b0 07 01 10 00 01 00 04 06 00 00 01 00 > 00000010: 00 00 50 05 00 00 00 00 00 01 ff 00 00 00 00 00 > 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > 00000030: 00 00 00 00 40 00 00 00 00 00 00 00 ff 01 00 00 > 00000040: 01 50 c3 5b 08 00 00 00 00 00 00 00 00 00 00 00 > 00000050: 05 70 80 01 00 00 00 00 00 00 00 00 00 00 00 00 > 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > 00000070: 10 b0 42 00 01 80 00 00 10 20 00 00 22 3c 73 00 > 00000080: 00 00 11 10 00 00 00 00 c0 03 40 00 00 00 01 00 > 00000090: 00 00 00 00 1f 04 00 00 00 00 00 00 06 00 00 00 > 000000a0: 02 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 > 000000b0: 11 00 00 01 00 20 00 00 00 40 00 00 00 00 00 00 > 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 I also noticed that the value of desc->pci.msix_ctrl obtained from the readl is always 0xffffffff irrespective of whether or not an endpoint device is connected. This isn't expected right? The only difference between the cases where endpoint device is connected and isn't connected is the completion timeout.
On Fri, Oct 13, 2023 at 10:36:01AM +0530, Siddharth Vadapalli wrote: > On 13/10/23 10:33, Siddharth Vadapalli wrote: > > On 12/10/23 22:13, Bjorn Helgaas wrote: > >> On Thu, Oct 12, 2023 at 10:15:09AM +0530, Siddharth Vadapalli wrote: > >>> On 11/10/23 19:16, Bjorn Helgaas wrote: > > ... > >>> msix_prepare_msi_desc > >>> In this function: msix_prepare_msi_desc, the following readl() > >>> causes completion timeout: > >>> desc->pci.msix_ctrl = readl(addr + PCI_MSIX_ENTRY_VECTOR_CTRL); > >>> The completion timeout with the readl is only observed when the link > >>> is down (No Endpoint device is actually connected to the PCIe > >>> connector slot). > >> > >> Do you know the address ("addr")? From pci_msix_desc_addr(), it looks > >> like it should be: > >> > >> desc->pci.mask_base + desc->msi_index * PCI_MSIX_ENTRY_SIZE > >> > >> and desc->pci.mask_base should be dev->msix_base, which we got from > >> msix_map_region(), which ioremaps part of the BAR indicated by the > >> MSI-X Table Offset/Table BIR register. > >> > >> I wonder if this readl() is being handled as an MMIO access to a > >> downstream device instead of a Root Port BAR access because it's > >> inside the Root Port's MMIO window. > >> > >> Could you dump out these values just before the readl()? > >> > >> phys_addr inside msix_map_region() > >> dev->msix_base > >> desc->pci.mask_base > >> desc->msi_index > >> addr > > > > phys_addr: 0x10102000 > > msix_base: 0xffff80000997a000 > > mask_base: 0xffff80000997a000 > > msi_index: 0 > > addr: 0xffff80000997a000 > > > > Also, the details of BAR allocation from the logs are: > > keystone-pcie 5500000.pcie: host bridge /bus@100000/pcie@5500000 ranges: > > keystone-pcie 5500000.pcie: IO 0x0010020000..0x001002ffff -> 0x0000000000 > > keystone-pcie 5500000.pcie: MEM 0x0010030000..0x0017ffffff -> 0x0010030000 > > keystone-pcie 5500000.pcie: iATU unroll: enabled > > keystone-pcie 5500000.pcie: iATU regions: 8 ob, 8 ib, align 64K, limit 4G > > keystone-pcie 5500000.pcie: Phy link never came up > > keystone-pcie 5500000.pcie: PCI host bridge to bus 0000:00 > > pci_bus 0000:00: root bus resource [bus 00-ff] > > pci_bus 0000:00: root bus resource [io 0x0000-0xffff] > > pci_bus 0000:00: root bus resource [mem 0x10030000-0x17ffffff] > > pci 0000:00:00.0: [104c:b00c] type 01 class 0x060400 > > pci 0000:00:00.0: reg 0x10: [mem 0x05500000-0x055fffff] > > pci 0000:00:00.0: reg 0x38: [mem 0x00000000-0x0000ffff pref] > > pci 0000:00:00.0: supports D1 > > pci 0000:00:00.0: PME# supported from D0 D1 D3hot > > pci 0000:00:00.0: BAR 0: assigned [mem 0x10100000-0x101fffff] > > pci 0000:00:00.0: BAR 6: assigned [mem 0x10030000-0x1003ffff pref] > > pci 0000:00:00.0: PCI bridge to [bus 01-ff] > > > > The value of phys_addr lies within the range allocated to BAR0. > > > >> call early_dump_pci_device() on the Root Port > > > > I invoked early_dump_pci_device() within the pci_setup_device() function in > > drivers/pci/probe.c and the output is: It'd be better to dump the config space immediately before the readl() since the PCI core did change some things in the interim. > > pci 0000:00:00.0: config space: > > 00000000: 4c 10 0c b0 07 01 10 00 01 00 04 06 00 00 01 00 PCI_COMMAND = 0x0107 PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER | PCI_COMMAND_SERR > > 00000010: 00 00 50 05 00 00 00 00 00 01 ff 00 00 00 00 00 > > 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 PCI_IO_BASE = 0x00 low 4 bits indicate 16-bit addressing PCI_IO_LIMIT = 0x00 PCI_MEMORY_BASE = 0x0000 PCI_MEMORY_LIMIT = 0x0000 PCI_PREF_MEMORY_BASE = 0x0000 low 4 bits indicate 32-bit pref PCI_PREF_MEMORY_LIMIT = 0x0000 PCI_PREF_BASE_UPPER32 = 0x00000000 PCI_PREF_LIMIT_UPPER32 = 0x00000000 We can't tell from this whether the prefetchable window is implemented (but I'm sure keystone *does* implement it). If PCI_PREF_MEMORY_BASE and PCI_PREF_MEMORY_LIMIT are read-only zeros, it is not implemented. If they are writable, it is enabled at the same range as the non-prefetchable window. Similarly for the I/O window; we can't tell whether the base/limit are read-only zero or writable. So we have these windows that look like they're probably enabled: io window at [io 0x0000-0x0fff] mem window at [mem 0x00000000-0x000fffff] pref window at [mem 0x00000000-0x000fffff pref] No idea whether it makes a difference, but these windows seem misconfigured. The default should probably be to make them all disabled (as in f73eedc90bf7 ("PCI: vmd: Disable bridge window for domain reset")): PCI_IO_BASE = 0xf0 PCI_IO_LIMIT = 0x00 PCI_MEMORY_BASE = 0xfff0 PCI_MEMORY_LIMIT = 0x0000 PCI_PREF_MEMORY_BASE = 0xfff0 PCI_PREF_MEMORY_LIMIT = 0x0000 PCI_PREF_BASE_UPPER32 = 0xffffffff PCI_PREF_LIMIT_UPPER32 = 0x00000000 The PCI core should reconfigure and enable them as needed by downstream devices. > I also noticed that the value of desc->pci.msix_ctrl obtained from > the readl is always 0xffffffff irrespective of whether or not an > endpoint device is connected. This isn't expected right? The only > difference between the cases where endpoint device is connected and > isn't connected is the completion timeout. Right, I wouldn't expect that. PCI_MSIX_ENTRY_VECTOR_CTRL has a bunch of reserved bits that should be zero. I assume MSI-X actually does work for downstream endpoints? I wouldn't think anybody would have bothered with ks_pcie_v3_65_add_bus() unless MSI-X works. Bjorn
On 14/10/23 00:19, Bjorn Helgaas wrote: > On Fri, Oct 13, 2023 at 10:36:01AM +0530, Siddharth Vadapalli wrote: >> On 13/10/23 10:33, Siddharth Vadapalli wrote: >>> On 12/10/23 22:13, Bjorn Helgaas wrote: >>>> On Thu, Oct 12, 2023 at 10:15:09AM +0530, Siddharth Vadapalli wrote: >>>>> On 11/10/23 19:16, Bjorn Helgaas wrote: >>> ... >>>>> msix_prepare_msi_desc >>>>> In this function: msix_prepare_msi_desc, the following readl() >>>>> causes completion timeout: >>>>> desc->pci.msix_ctrl = readl(addr + PCI_MSIX_ENTRY_VECTOR_CTRL); >>>>> The completion timeout with the readl is only observed when the link >>>>> is down (No Endpoint device is actually connected to the PCIe >>>>> connector slot). >>>> >>>> Do you know the address ("addr")? From pci_msix_desc_addr(), it looks >>>> like it should be: >>>> >>>> desc->pci.mask_base + desc->msi_index * PCI_MSIX_ENTRY_SIZE >>>> >>>> and desc->pci.mask_base should be dev->msix_base, which we got from >>>> msix_map_region(), which ioremaps part of the BAR indicated by the >>>> MSI-X Table Offset/Table BIR register. >>>> >>>> I wonder if this readl() is being handled as an MMIO access to a >>>> downstream device instead of a Root Port BAR access because it's >>>> inside the Root Port's MMIO window. >>>> >>>> Could you dump out these values just before the readl()? >>>> >>>> phys_addr inside msix_map_region() >>>> dev->msix_base >>>> desc->pci.mask_base >>>> desc->msi_index >>>> addr >>> >>> phys_addr: 0x10102000 >>> msix_base: 0xffff80000997a000 >>> mask_base: 0xffff80000997a000 >>> msi_index: 0 >>> addr: 0xffff80000997a000 >>> >>> Also, the details of BAR allocation from the logs are: >>> keystone-pcie 5500000.pcie: host bridge /bus@100000/pcie@5500000 ranges: >>> keystone-pcie 5500000.pcie: IO 0x0010020000..0x001002ffff -> 0x0000000000 >>> keystone-pcie 5500000.pcie: MEM 0x0010030000..0x0017ffffff -> 0x0010030000 >>> keystone-pcie 5500000.pcie: iATU unroll: enabled >>> keystone-pcie 5500000.pcie: iATU regions: 8 ob, 8 ib, align 64K, limit 4G >>> keystone-pcie 5500000.pcie: Phy link never came up >>> keystone-pcie 5500000.pcie: PCI host bridge to bus 0000:00 >>> pci_bus 0000:00: root bus resource [bus 00-ff] >>> pci_bus 0000:00: root bus resource [io 0x0000-0xffff] >>> pci_bus 0000:00: root bus resource [mem 0x10030000-0x17ffffff] >>> pci 0000:00:00.0: [104c:b00c] type 01 class 0x060400 >>> pci 0000:00:00.0: reg 0x10: [mem 0x05500000-0x055fffff] >>> pci 0000:00:00.0: reg 0x38: [mem 0x00000000-0x0000ffff pref] >>> pci 0000:00:00.0: supports D1 >>> pci 0000:00:00.0: PME# supported from D0 D1 D3hot >>> pci 0000:00:00.0: BAR 0: assigned [mem 0x10100000-0x101fffff] >>> pci 0000:00:00.0: BAR 6: assigned [mem 0x10030000-0x1003ffff pref] >>> pci 0000:00:00.0: PCI bridge to [bus 01-ff] >>> >>> The value of phys_addr lies within the range allocated to BAR0. >>> >>>> call early_dump_pci_device() on the Root Port >>> >>> I invoked early_dump_pci_device() within the pci_setup_device() function in >>> drivers/pci/probe.c and the output is: > > It'd be better to dump the config space immediately before the readl() > since the PCI core did change some things in the interim. I dumped the config space just before the readl() and it is: pcieport 0000:00:00.0: config space: 00000000: 4c 10 0c b0 07 01 10 00 01 00 04 06 00 00 01 00 00000010: 00 00 10 10 00 00 00 00 00 01 ff 00 f0 00 00 00 00000020: f0 ff 00 00 f0 ff 00 00 00 00 00 00 00 00 00 00 00000030: 00 00 00 00 40 00 00 00 00 00 00 00 17 01 02 00 00000040: 01 50 c3 5b 08 00 00 00 00 00 00 00 00 00 00 00 00000050: 05 70 80 01 00 00 00 00 00 00 00 00 00 00 00 00 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00000070: 10 b0 42 00 01 80 00 00 1f 20 00 00 22 3c 73 00 00000080: 00 00 11 10 00 00 00 00 c0 03 40 00 10 00 01 00 00000090: 00 00 00 00 1f 04 00 00 00 00 00 00 06 00 00 00 000000a0: 02 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 000000b0: 11 00 00 c1 00 20 00 00 00 40 00 00 00 00 00 00 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 BAR0 was configured with the value: 0x05500000 within ks_pcie_v3_65_add_bus() at: dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, ks_pcie->app.start); and can be verified based on the previous config space dump I had shared within the pci_setup_device() function. But, looking at the dump above which is just before the readl(), its value seems to have changed to 0x10100000. I am listing down the regions of config space which have changed, based on the comparison of dumps taken within pci_setup_device() and just before the readl(): Within pci_setup_device(): 00000010: 00 00 50 05 00 00 00 00 00 01 ff 00 00 00 00 00 Before readl(): 00000010: 00 00 10 10 00 00 00 00 00 01 ff 00 f0 00 00 00 Within pci_setup_device(): 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Before readl(): 00000020: f0 ff 00 00 f0 ff 00 00 00 00 00 00 00 00 00 00 Within pci_setup_device(): 00000030: 00 00 00 00 40 00 00 00 00 00 00 00 ff 01 00 00 Before readl(): 00000030: 00 00 00 00 40 00 00 00 00 00 00 00 17 01 02 00 Within pci_setup_device(): 00000070: 10 b0 42 00 01 80 00 00 10 20 00 00 22 3c 73 00 Before readl(): 00000070: 10 b0 42 00 01 80 00 00 1f 20 00 00 22 3c 73 00 Within pci_setup_device(): 00000080: 00 00 11 10 00 00 00 00 c0 03 40 00 00 00 01 00 Before readl(): 00000080: 00 00 11 10 00 00 00 00 c0 03 40 00 10 00 01 00 Within pci_setup_device(): 000000b0: 11 00 00 01 00 20 00 00 00 40 00 00 00 00 00 00 Before readl(): 000000b0: 11 00 00 c1 00 20 00 00 00 40 00 00 00 00 00 00 > >>> pci 0000:00:00.0: config space: >>> 00000000: 4c 10 0c b0 07 01 10 00 01 00 04 06 00 00 01 00 > > PCI_COMMAND = 0x0107 > PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER | PCI_COMMAND_SERR > >>> 00000010: 00 00 50 05 00 00 00 00 00 01 ff 00 00 00 00 00 >>> 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > PCI_IO_BASE = 0x00 low 4 bits indicate 16-bit addressing > PCI_IO_LIMIT = 0x00 > PCI_MEMORY_BASE = 0x0000 > PCI_MEMORY_LIMIT = 0x0000 > PCI_PREF_MEMORY_BASE = 0x0000 low 4 bits indicate 32-bit pref > PCI_PREF_MEMORY_LIMIT = 0x0000 > PCI_PREF_BASE_UPPER32 = 0x00000000 > PCI_PREF_LIMIT_UPPER32 = 0x00000000 > > We can't tell from this whether the prefetchable window is implemented > (but I'm sure keystone *does* implement it). If PCI_PREF_MEMORY_BASE > and PCI_PREF_MEMORY_LIMIT are read-only zeros, it is not implemented. > If they are writable, it is enabled at the same range as the > non-prefetchable window. Yes, PCI_PREF_MEMORY_BASE and PCI_PREF_MEMORY_LIMIT are writable. > > Similarly for the I/O window; we can't tell whether the base/limit are > read-only zero or writable. PCI_IO_BASE and PCI_IO_LIMIT are also writable. > > So we have these windows that look like they're probably enabled: > > io window at [io 0x0000-0x0fff] > mem window at [mem 0x00000000-0x000fffff] > pref window at [mem 0x00000000-0x000fffff pref] > > No idea whether it makes a difference, but these windows seem > misconfigured. The default should probably be to make them all > disabled (as in f73eedc90bf7 ("PCI: vmd: Disable bridge window for > domain reset")): > > PCI_IO_BASE = 0xf0 > PCI_IO_LIMIT = 0x00 > PCI_MEMORY_BASE = 0xfff0 > PCI_MEMORY_LIMIT = 0x0000 > PCI_PREF_MEMORY_BASE = 0xfff0 > PCI_PREF_MEMORY_LIMIT = 0x0000 > PCI_PREF_BASE_UPPER32 = 0xffffffff > PCI_PREF_LIMIT_UPPER32 = 0x00000000 > > The PCI core should reconfigure and enable them as needed by > downstream devices. > >> I also noticed that the value of desc->pci.msix_ctrl obtained from >> the readl is always 0xffffffff irrespective of whether or not an >> endpoint device is connected. This isn't expected right? The only >> difference between the cases where endpoint device is connected and >> isn't connected is the completion timeout. > > Right, I wouldn't expect that. PCI_MSIX_ENTRY_VECTOR_CTRL has a bunch > of reserved bits that should be zero. > > I assume MSI-X actually does work for downstream endpoints? I > wouldn't think anybody would have bothered with > ks_pcie_v3_65_add_bus() unless MSI-X works. Yes, I think it is supposed to work, but it doesn't seem to be working right now considering that even with Endpoint device connected, the readl() returns all Fs.
Hi Siddharth On Sat, Oct 14, 2023 at 11:22:48AM +0530, Siddharth Vadapalli wrote: > > > On 14/10/23 00:19, Bjorn Helgaas wrote: > > On Fri, Oct 13, 2023 at 10:36:01AM +0530, Siddharth Vadapalli wrote: > >> On 13/10/23 10:33, Siddharth Vadapalli wrote: > >>> On 12/10/23 22:13, Bjorn Helgaas wrote: > >>>> On Thu, Oct 12, 2023 at 10:15:09AM +0530, Siddharth Vadapalli wrote: > >>>>> On 11/10/23 19:16, Bjorn Helgaas wrote: > >>> ... > >>>>> msix_prepare_msi_desc > >>>>> In this function: msix_prepare_msi_desc, the following readl() > >>>>> causes completion timeout: > >>>>> desc->pci.msix_ctrl = readl(addr + PCI_MSIX_ENTRY_VECTOR_CTRL); > >>>>> The completion timeout with the readl is only observed when the link > >>>>> is down (No Endpoint device is actually connected to the PCIe > >>>>> connector slot). > >>>> > >>>> Do you know the address ("addr")? From pci_msix_desc_addr(), it looks > >>>> like it should be: > >>>> > >>>> desc->pci.mask_base + desc->msi_index * PCI_MSIX_ENTRY_SIZE > >>>> > >>>> and desc->pci.mask_base should be dev->msix_base, which we got from > >>>> msix_map_region(), which ioremaps part of the BAR indicated by the > >>>> MSI-X Table Offset/Table BIR register. > >>>> > >>>> I wonder if this readl() is being handled as an MMIO access to a > >>>> downstream device instead of a Root Port BAR access because it's > >>>> inside the Root Port's MMIO window. > >>>> > >>>> Could you dump out these values just before the readl()? > >>>> > >>>> phys_addr inside msix_map_region() > >>>> dev->msix_base > >>>> desc->pci.mask_base > >>>> desc->msi_index > >>>> addr > >>> > >>> phys_addr: 0x10102000 > >>> msix_base: 0xffff80000997a000 > >>> mask_base: 0xffff80000997a000 > >>> msi_index: 0 > >>> addr: 0xffff80000997a000 > >>> > >>> Also, the details of BAR allocation from the logs are: > >>> keystone-pcie 5500000.pcie: host bridge /bus@100000/pcie@5500000 ranges: > >>> keystone-pcie 5500000.pcie: IO 0x0010020000..0x001002ffff -> 0x0000000000 > >>> keystone-pcie 5500000.pcie: MEM 0x0010030000..0x0017ffffff -> 0x0010030000 > >>> keystone-pcie 5500000.pcie: iATU unroll: enabled > >>> keystone-pcie 5500000.pcie: iATU regions: 8 ob, 8 ib, align 64K, limit 4G > >>> keystone-pcie 5500000.pcie: Phy link never came up > >>> keystone-pcie 5500000.pcie: PCI host bridge to bus 0000:00 > >>> pci_bus 0000:00: root bus resource [bus 00-ff] > >>> pci_bus 0000:00: root bus resource [io 0x0000-0xffff] > >>> pci_bus 0000:00: root bus resource [mem 0x10030000-0x17ffffff] > >>> pci 0000:00:00.0: [104c:b00c] type 01 class 0x060400 > >>> pci 0000:00:00.0: reg 0x10: [mem 0x05500000-0x055fffff] > >>> pci 0000:00:00.0: reg 0x38: [mem 0x00000000-0x0000ffff pref] > >>> pci 0000:00:00.0: supports D1 > >>> pci 0000:00:00.0: PME# supported from D0 D1 D3hot > >>> pci 0000:00:00.0: BAR 0: assigned [mem 0x10100000-0x101fffff] > >>> pci 0000:00:00.0: BAR 6: assigned [mem 0x10030000-0x1003ffff pref] > >>> pci 0000:00:00.0: PCI bridge to [bus 01-ff] > >>> > >>> The value of phys_addr lies within the range allocated to BAR0. > >>> > >>>> call early_dump_pci_device() on the Root Port > >>> > >>> I invoked early_dump_pci_device() within the pci_setup_device() function in > >>> drivers/pci/probe.c and the output is: > > > > It'd be better to dump the config space immediately before the readl() > > since the PCI core did change some things in the interim. > > I dumped the config space just before the readl() and it is: > > pcieport 0000:00:00.0: config space: > 00000000: 4c 10 0c b0 07 01 10 00 01 00 04 06 00 00 01 00 > 00000010: 00 00 10 10 00 00 00 00 00 01 ff 00 f0 00 00 00 > 00000020: f0 ff 00 00 f0 ff 00 00 00 00 00 00 00 00 00 00 > 00000030: 00 00 00 00 40 00 00 00 00 00 00 00 17 01 02 00 > 00000040: 01 50 c3 5b 08 00 00 00 00 00 00 00 00 00 00 00 > 00000050: 05 70 80 01 00 00 00 00 00 00 00 00 00 00 00 00 > 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > 00000070: 10 b0 42 00 01 80 00 00 1f 20 00 00 22 3c 73 00 > 00000080: 00 00 11 10 00 00 00 00 c0 03 40 00 10 00 01 00 > 00000090: 00 00 00 00 1f 04 00 00 00 00 00 00 06 00 00 00 > 000000a0: 02 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 > 000000b0: 11 00 00 c1 00 20 00 00 00 40 00 00 00 00 00 00 > 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > BAR0 was configured with the value: 0x05500000 within ks_pcie_v3_65_add_bus() at: > dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, ks_pcie->app.start); > and can be verified based on the previous config space dump I had shared within > the pci_setup_device() function. But, looking at the dump above which is just > before the readl(), its value seems to have changed to 0x10100000. > > I am listing down the regions of config space which have changed, based on the > comparison of dumps taken within pci_setup_device() and just before the readl(): > > Within pci_setup_device(): > 00000010: 00 00 50 05 00 00 00 00 00 01 ff 00 00 00 00 00 > Before readl(): > 00000010: 00 00 10 10 00 00 00 00 00 01 ff 00 f0 00 00 00 > > Within pci_setup_device(): > 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > Before readl(): > 00000020: f0 ff 00 00 f0 ff 00 00 00 00 00 00 00 00 00 00 > > Within pci_setup_device(): > 00000030: 00 00 00 00 40 00 00 00 00 00 00 00 ff 01 00 00 > Before readl(): > 00000030: 00 00 00 00 40 00 00 00 00 00 00 00 17 01 02 00 > > Within pci_setup_device(): > 00000070: 10 b0 42 00 01 80 00 00 10 20 00 00 22 3c 73 00 > Before readl(): > 00000070: 10 b0 42 00 01 80 00 00 1f 20 00 00 22 3c 73 00 > > Within pci_setup_device(): > 00000080: 00 00 11 10 00 00 00 00 c0 03 40 00 00 00 01 00 > Before readl(): > 00000080: 00 00 11 10 00 00 00 00 c0 03 40 00 10 00 01 00 > > Within pci_setup_device(): > 000000b0: 11 00 00 01 00 20 00 00 00 40 00 00 00 00 00 00 > Before readl(): > 000000b0: 11 00 00 c1 00 20 00 00 00 40 00 00 00 00 00 00 > > > > >>> pci 0000:00:00.0: config space: > >>> 00000000: 4c 10 0c b0 07 01 10 00 01 00 04 06 00 00 01 00 > > > > PCI_COMMAND = 0x0107 > > PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER | PCI_COMMAND_SERR > > > >>> 00000010: 00 00 50 05 00 00 00 00 00 01 ff 00 00 00 00 00 > >>> 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > PCI_IO_BASE = 0x00 low 4 bits indicate 16-bit addressing > > PCI_IO_LIMIT = 0x00 > > PCI_MEMORY_BASE = 0x0000 > > PCI_MEMORY_LIMIT = 0x0000 > > PCI_PREF_MEMORY_BASE = 0x0000 low 4 bits indicate 32-bit pref > > PCI_PREF_MEMORY_LIMIT = 0x0000 > > PCI_PREF_BASE_UPPER32 = 0x00000000 > > PCI_PREF_LIMIT_UPPER32 = 0x00000000 > > > > We can't tell from this whether the prefetchable window is implemented > > (but I'm sure keystone *does* implement it). If PCI_PREF_MEMORY_BASE > > and PCI_PREF_MEMORY_LIMIT are read-only zeros, it is not implemented. > > If they are writable, it is enabled at the same range as the > > non-prefetchable window. > > Yes, PCI_PREF_MEMORY_BASE and PCI_PREF_MEMORY_LIMIT are writable. > > > > > Similarly for the I/O window; we can't tell whether the base/limit are > > read-only zero or writable. > > PCI_IO_BASE and PCI_IO_LIMIT are also writable. > > > > > So we have these windows that look like they're probably enabled: > > > > io window at [io 0x0000-0x0fff] > > mem window at [mem 0x00000000-0x000fffff] > > pref window at [mem 0x00000000-0x000fffff pref] > > > > No idea whether it makes a difference, but these windows seem > > misconfigured. The default should probably be to make them all > > disabled (as in f73eedc90bf7 ("PCI: vmd: Disable bridge window for > > domain reset")): > > > > PCI_IO_BASE = 0xf0 > > PCI_IO_LIMIT = 0x00 > > PCI_MEMORY_BASE = 0xfff0 > > PCI_MEMORY_LIMIT = 0x0000 > > PCI_PREF_MEMORY_BASE = 0xfff0 > > PCI_PREF_MEMORY_LIMIT = 0x0000 > > PCI_PREF_BASE_UPPER32 = 0xffffffff > > PCI_PREF_LIMIT_UPPER32 = 0x00000000 > > > > The PCI core should reconfigure and enable them as needed by > > downstream devices. > > > >> I also noticed that the value of desc->pci.msix_ctrl obtained from > >> the readl is always 0xffffffff irrespective of whether or not an > >> endpoint device is connected. This isn't expected right? The only > >> difference between the cases where endpoint device is connected and > >> isn't connected is the completion timeout. > > > > Right, I wouldn't expect that. PCI_MSIX_ENTRY_VECTOR_CTRL has a bunch > > of reserved bits that should be zero. > > > > I assume MSI-X actually does work for downstream endpoints? I > > wouldn't think anybody would have bothered with > > ks_pcie_v3_65_add_bus() unless MSI-X works. > > Yes, I think it is supposed to work, but it doesn't seem to be working right now > considering that even with Endpoint device connected, the readl() returns all Fs. Could you please have look at what DW PCIe IP-core version is utilized in the Keystone PCIe host controller? If it's of v5.x then here is what HW databook says about the BARs initialization: "If you do use a BAR, then you should program it to capture TLPs that are targeted to your local non-application memory space residing on TRGT1, and not for the application on TRGT0 (dbi). The BAR range must be outside of the three Base/Limit regions." I have no idea whether the BAR being set with an address within the Base/Limit regions could have caused the lags you see, but I would have at least checked that. -Serge(y) > > -- > Regards, > Siddharth.
Hello, On 17/10/23 02:59, Serge Semin wrote: > Hi Siddharth > ... >>> >>> I assume MSI-X actually does work for downstream endpoints? I >>> wouldn't think anybody would have bothered with >>> ks_pcie_v3_65_add_bus() unless MSI-X works. >> >> Yes, I think it is supposed to work, but it doesn't seem to be working right now >> considering that even with Endpoint device connected, the readl() returns all Fs. > > Could you please have look at what DW PCIe IP-core version is utilized > in the Keystone PCIe host controller? If it's of v5.x then here is The DW PCIe IP-core version is 4.90a. > what HW databook says about the BARs initialization: "If you do use a > BAR, then you should program it to capture TLPs that are targeted to > your local non-application memory space residing on TRGT1, and not for > the application on TRGT0 (dbi). The BAR range must be outside of the > three Base/Limit regions." Yes, it's the same even in the DW PCIe IP-core version 4.90a Databook: 3.5.7.2 RC Mode Two BARs are present but are not expected to be used. You should disable them or else they will be unnecessarily assigned memory during device enumeration. If you do use a BAR, then you should program it to capture TLPs that are targeted to your local non-application memory space residing on TRGT1, and not for the application on TRGT1. The BAR range must be outside of the three Base/Limit regions. > > I have no idea whether the BAR being set with an address within the > Base/Limit regions could have caused the lags you see, but I would > have at least checked that. I will check that. Thank you for sharing your feedback. > > -Serge(y) > >> >> -- >> Regards, >> Siddharth.
On Tue, Oct 17, 2023 at 09:44:51AM +0530, Siddharth Vadapalli wrote: > Hello, > > On 17/10/23 02:59, Serge Semin wrote: > > Hi Siddharth > > > > ... > > >>> > >>> I assume MSI-X actually does work for downstream endpoints? I > >>> wouldn't think anybody would have bothered with > >>> ks_pcie_v3_65_add_bus() unless MSI-X works. > >> > >> Yes, I think it is supposed to work, but it doesn't seem to be working right now > >> considering that even with Endpoint device connected, the readl() returns all Fs. > > > > Could you please have look at what DW PCIe IP-core version is utilized > > in the Keystone PCIe host controller? If it's of v5.x then here is > > The DW PCIe IP-core version is 4.90a. > > > what HW databook says about the BARs initialization: "If you do use a > > BAR, then you should program it to capture TLPs that are targeted to > > your local non-application memory space residing on TRGT1, and not for > > the application on TRGT0 (dbi). The BAR range must be outside of the > > three Base/Limit regions." > > Yes, it's the same even in the DW PCIe IP-core version 4.90a Databook: > > 3.5.7.2 RC Mode > > Two BARs are present but are not expected to be used. You should disable them or > else they will be unnecessarily assigned memory during device enumeration. If > you do use a BAR, then you should program it to capture TLPs that are targeted > to your local non-application memory space residing on TRGT1, and not for the > application on TRGT1. The BAR range must be outside of the three Base/Limit regions. Are you really sure that it's 4.90a? Here is what my DW PCIe RC _v4.90_ HW databook says about the BARs: "Base Address Registers (Offset: 0x10-x14) The Synopsys core does not implement the optional BARs for the RC product. This is based on the assumption that the RC host probably has registers on some other internal bus and has knowledge and setup access to these registers already." What you cited resides in the _v5.x_ databooks. It makes my thinking that in your case the IP-core isn't of 4.90a version. -Serge(y) > > > > > I have no idea whether the BAR being set with an address within the > > Base/Limit regions could have caused the lags you see, but I would > > have at least checked that. > > I will check that. Thank you for sharing your feedback. > > > > > -Serge(y) > > > >> > >> -- > >> Regards, > >> Siddharth. > > -- > Regards, > Siddharth.
On 18/10/23 16:12, Serge Semin wrote: > On Tue, Oct 17, 2023 at 09:44:51AM +0530, Siddharth Vadapalli wrote: >> Hello, >> >> On 17/10/23 02:59, Serge Semin wrote: >>> Hi Siddharth >>> >> >> ... >> ... > > Are you really sure that it's 4.90a? Here is what my DW PCIe RC > _v4.90_ HW databook says about the BARs: > > "Base Address Registers (Offset: 0x10-x14) The Synopsys core does not > implement the optional BARs for the RC product. This is based on the > assumption that the RC host probably has registers on some other > internal bus and has knowledge and setup access to these registers > already." > > What you cited resides in the _v5.x_ databooks. It makes my thinking > that in your case the IP-core isn't of 4.90a version. I reviewed the function ks_pcie_v3_65_add_bus() and it appears clear to me now that it is applicable only to 3.65a versions. The IP-core however is 4.90a. I have posted the v2 patch at: https://lore.kernel.org/r/20231018075038.2740534-1-s-vadapalli@ti.com/ Also, as pointed out by Ravi on the v2 patch's thread at: https://lore.kernel.org/r/c546f8e9-f6ba-41b8-7dff-4a7921b6705f@ti.com/ the culprit turned out to be: 6ab15b5e7057 (PCI: dwc: keystone: Convert .scan_bus() callback to use add_bus) which in the process of converting the .scan_bus() callback to .add_bus(), namely: ks_pcie_v3_65_scan_bus() -> ks_pcie_v3_65_add_bus() It added the .add_bus() method within "struct pci_ops ks_pcie_ops" which is actually shared with the 4.90a controller as well. So an "is_am6" check should have also been added to make it no-op for NON-3.65a controllers. I will be posting the v3 patch implementing the above fix if there is no further feedback on the v2 patch from others.
diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c index 49aea6ce3e87..ac2ad112d616 100644 --- a/drivers/pci/controller/dwc/pci-keystone.c +++ b/drivers/pci/controller/dwc/pci-keystone.c @@ -459,7 +459,8 @@ static int ks_pcie_v3_65_add_bus(struct pci_bus *bus) struct dw_pcie *pci = to_dw_pcie_from_pp(pp); struct keystone_pcie *ks_pcie = to_keystone_pcie(pci); - if (!pci_is_root_bus(bus)) + /* Don't enable BAR0 if link is not yet up at this point */ + if (!pci_is_root_bus(bus) || !dw_pcie_link_up(pci)) return 0; /* Configure and set up BAR0 */
Since the function dw_pcie_host_init() ignores the absence of link under the assumption that link can come up later, it is possible that the pci_host_probe(bridge) function is invoked even when no endpoint device is connected. In such a situation, the ks_pcie_v3_65_add_bus() function configures BAR0 when the link is not up, resulting in Completion Timeouts during the MSI configuration performed later by the PCI Express Port driver to setup AER, PME and other services. Thus, leave BAR0 disabled if link is not yet detected when the ks_pcie_v3_65_add_bus() function is invoked. Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com> --- Hello, This patch is based on linux-next tagged next-20231011. Regards, Siddharth. drivers/pci/controller/dwc/pci-keystone.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)