| Message ID | 20160613190550.12503.18319.stgit@bhelgaas-glaptop2.roam.corp.google.com |
|---|---|
| State | Accepted |
| Headers | show |
Hi,
[auto build test WARNING on pci/next]
[also build test WARNING on v4.7-rc3 next-20160609]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Bjorn-Helgaas/PCI-Precision-Time-Measurement-support/20160614-031902
base: https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git next
config: i386-defconfig (attached as .config)
compiler: gcc-6 (Debian 6.1.1-1) 6.1.1 20160430
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings
All warnings (new ones prefixed by >>):
drivers/pci/pcie/ptm.c: In function 'pci_enable_ptm':
>> drivers/pci/pcie/ptm.c:129:28: warning: 'ups' may be used uninitialized in this function [-Wmaybe-uninitialized]
dev->ptm_granularity = ups->ptm_granularity;
~~~^~~~~~~~~~~~~~~~~
vim +/ups +129 drivers/pci/pcie/ptm.c
113 * For Root Complex Integrated Endpoints, there is no upstream
114 * device, so there must be some implementation-specific way to
115 * associate the endpoint with a time source.
116 */
117 if (pci_pcie_type(dev) == PCI_EXP_TYPE_ENDPOINT) {
118 /* PTM is only useful if an upstream device has it enabled */
119 ups = pci_upstream_bridge(dev);
120 if (!ups || !ups->ptm_enabled)
121 return -EINVAL;
122 } else if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_END)
123 return -EINVAL;
124
125 pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap);
126 if (!(cap & PCI_PTM_CAP_REQ))
127 return -EINVAL;
128
> 129 dev->ptm_granularity = ups->ptm_granularity;
130
131 ctrl = PCI_PTM_CTRL_ENABLE;
132 pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl);
133 dev->ptm_enabled = 1;
134
135 pci_ptm_info(dev);
136
137 if (granularity)
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c index 9cfa64a..a6ec4ae 100644 --- a/drivers/pci/pcie/ptm.c +++ b/drivers/pci/pcie/ptm.c @@ -19,7 +19,22 @@ static void pci_ptm_info(struct pci_dev *dev) { - dev_info(&dev->dev, "PTM enabled%s\n", dev->ptm_root ? " (root)" : ""); + char clock_desc[8]; + + switch (dev->ptm_granularity) { + case 0: + snprintf(clock_desc, sizeof(clock_desc), "unknown"); + break; + case 255: + snprintf(clock_desc, sizeof(clock_desc), ">254ns"); + break; + default: + snprintf(clock_desc, sizeof(clock_desc), "%udns", + dev->ptm_granularity); + break; + } + dev_info(&dev->dev, "PTM enabled%s, %s granularity\n", + dev->ptm_root ? " (root)" : "", clock_desc); } void pci_ptm_init(struct pci_dev *dev) @@ -27,6 +42,7 @@ void pci_ptm_init(struct pci_dev *dev) int pos; struct pci_dev *ups; u32 cap, ctrl; + u8 local_clock; if (!pci_is_pcie(dev)) return; @@ -45,6 +61,7 @@ void pci_ptm_init(struct pci_dev *dev) return; pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap); + local_clock = (cap & PCI_PTM_GRANULARITY_MASK) >> 8; /* * There's no point in enabling PTM unless it's enabled in the @@ -55,14 +72,20 @@ void pci_ptm_init(struct pci_dev *dev) ups = pci_upstream_bridge(dev); if (ups && ups->ptm_enabled) { ctrl = PCI_PTM_CTRL_ENABLE; + if (ups->ptm_granularity == 0) + dev->ptm_granularity = 0; + else if (ups->ptm_granularity > local_clock) + dev->ptm_granularity = ups->ptm_granularity; } else { if (cap & PCI_PTM_CAP_ROOT) { ctrl = PCI_PTM_CTRL_ENABLE | PCI_PTM_CTRL_ROOT; dev->ptm_root = 1; + dev->ptm_granularity = local_clock; } else return; } + ctrl |= dev->ptm_granularity << 8; pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl); dev->ptm_enabled = 1; @@ -103,6 +126,8 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity) if (!(cap & PCI_PTM_CAP_REQ)) return -EINVAL; + dev->ptm_granularity = ups->ptm_granularity; + ctrl = PCI_PTM_CTRL_ENABLE; pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl); dev->ptm_enabled = 1; @@ -110,6 +135,6 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity) pci_ptm_info(dev); if (granularity) - *granularity = 0; + *granularity = dev->ptm_granularity; return 0; } diff --git a/include/linux/pci.h b/include/linux/pci.h index 593b2c1..73b70d3 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -365,6 +365,7 @@ struct pci_dev { #ifdef CONFIG_PCIE_PTM unsigned int ptm_root:1; unsigned int ptm_enabled:1; + u8 ptm_granularity; #endif #ifdef CONFIG_PCI_MSI const struct attribute_group **msi_irq_groups; diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h index 72bbe14..d812172 100644 --- a/include/uapi/linux/pci_regs.h +++ b/include/uapi/linux/pci_regs.h @@ -969,6 +969,7 @@ #define PCI_PTM_CAP 0x04 /* PTM Capability */ #define PCI_PTM_CAP_REQ 0x00000001 /* Requester capable */ #define PCI_PTM_CAP_ROOT 0x00000004 /* Root capable */ +#define PCI_PTM_GRANULARITY_MASK 0x0000FF00 /* Clock granularity */ #define PCI_PTM_CTRL 0x08 /* PTM Control */ #define PCI_PTM_CTRL_ENABLE 0x00000001 /* PTM enable */ #define PCI_PTM_CTRL_ROOT 0x00000002 /* Root select */
I don't know how to figure out clock granularity for Root Complex Integrated Endpoints. The spec (PCIe r3.1, sec 7.32.3) says: system software must set [Effective Granularity] to the value reported in the Local Clock Granularity field by the associated PTM Time Source but I don't know how to identify the associated PTM Time Source. An integrated endpoint has no upstream bridge. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> --- drivers/pci/pcie/ptm.c | 29 +++++++++++++++++++++++++++-- include/linux/pci.h | 1 + include/uapi/linux/pci_regs.h | 1 + 3 files changed, 29 insertions(+), 2 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html