From: "Saheed O. Bolarinwa" <refactormyself@xxxxxxxxx>
Previously we stored the "ASPM Support" field from the Link Capabilities
register in the struct aspm_register_info.
Read the Link Capabilities directly when needed and remove it from the
struct aspm_register_info. No functional change intended.
[bhelgaas: remove pci_dev cached copy since LNKCAP isn't truly read-only,
add PCI_EXP_LNKCAP_ASPM_L0S & PCI_EXP_LNKCAP_ASPM_L1, check them directly
instead of adding aspm_support()]
Signed-off-by: Saheed O. Bolarinwa <refactormyself@xxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
---
drivers/pci/pcie/aspm.c | 25 ++++++++++++++-----------
include/uapi/linux/pci_regs.h | 2 ++
2 files changed, 16 insertions(+), 11 deletions(-)
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 0725511cbeb5..82ce34e2ef53 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -381,7 +381,6 @@ static void encode_l12_threshold(u32 threshold_us, u32 *scale, u32 *value)
}
struct aspm_register_info {
- u32 support:2;
u32 enabled:2;
u32 latency_encoding_l0s;
u32 latency_encoding_l1;
@@ -400,7 +399,6 @@ static void pcie_get_aspm_reg(struct pci_dev *pdev,
u32 reg32;
pcie_capability_read_dword(pdev, PCI_EXP_LNKCAP, ®32);
- info->support = (reg32 & PCI_EXP_LNKCAP_ASPMS) >> 10;
info->latency_encoding_l0s = (reg32 & PCI_EXP_LNKCAP_L0SEL) >> 12;
info->latency_encoding_l1 = (reg32 & PCI_EXP_LNKCAP_L1EL) >> 15;
pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, ®16);
@@ -550,6 +548,7 @@ static void aspm_calc_l1ss_info(struct pcie_link_state *link,
static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
{
struct pci_dev *child = link->downstream, *parent = link->pdev;
+ u32 parent_lnkcap, child_lnkcap;
struct pci_bus *linkbus = parent->subordinate;
struct aspm_register_info upreg, dwreg;
@@ -560,24 +559,26 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
return;
}
- /* Get upstream/downstream components' register state */
- pcie_get_aspm_reg(parent, &upreg);
- pcie_get_aspm_reg(child, &dwreg);
-
/*
* If ASPM not supported, don't mess with the clocks and link,
* bail out now.
*/
- if (!(upreg.support & dwreg.support))
+ pcie_capability_read_dword(parent, PCI_EXP_LNKCAP, &parent_lnkcap);
+ pcie_capability_read_dword(child, PCI_EXP_LNKCAP, &child_lnkcap);
+ if (!(parent_lnkcap & child_lnkcap & PCI_EXP_LNKCAP_ASPMS))
return;
/* Configure common clock before checking latencies */
pcie_aspm_configure_common_clock(link);
/*
- * Re-read upstream/downstream components' register state
- * after clock configuration
+ * Re-read upstream/downstream components' register state after
+ * clock configuration. L0s & L1 exit latencies in the otherwise
+ * read-only Link Capabilities may change depending on common clock
+ * configuration (PCIe r5.0, sec 7.5.3.6).
*/
+ pcie_capability_read_dword(parent, PCI_EXP_LNKCAP, &parent_lnkcap);
+ pcie_capability_read_dword(child, PCI_EXP_LNKCAP, &child_lnkcap);
pcie_get_aspm_reg(parent, &upreg);
pcie_get_aspm_reg(child, &dwreg);
@@ -588,8 +589,9 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
* given link unless components on both sides of the link each
* support L0s.
*/
- if (dwreg.support & upreg.support & PCIE_LINK_STATE_L0S)
+ if (parent_lnkcap & child_lnkcap & PCI_EXP_LNKCAP_ASPM_L0S)
link->aspm_support |= ASPM_STATE_L0S;
+
if (dwreg.enabled & PCIE_LINK_STATE_L0S)
link->aspm_enabled |= ASPM_STATE_L0S_UP;
if (upreg.enabled & PCIE_LINK_STATE_L0S)
@@ -598,8 +600,9 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
link->latency_dw.l0s = calc_l0s_latency(dwreg.latency_encoding_l0s);
/* Setup L1 state */
- if (upreg.support & dwreg.support & PCIE_LINK_STATE_L1)
+ if (parent_lnkcap & child_lnkcap & PCI_EXP_LNKCAP_ASPM_L1)
link->aspm_support |= ASPM_STATE_L1;
+
if (upreg.enabled & dwreg.enabled & PCIE_LINK_STATE_L1)
link->aspm_enabled |= ASPM_STATE_L1;
link->latency_up.l1 = calc_l1_latency(upreg.latency_encoding_l1);
diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index f9701410d3b5..06846ec2e071 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -532,6 +532,8 @@
#define PCI_EXP_LNKCAP_SLS_32_0GB 0x00000005 /* LNKCAP2 SLS Vector bit 4 */
#define PCI_EXP_LNKCAP_MLW 0x000003f0 /* Maximum Link Width */
#define PCI_EXP_LNKCAP_ASPMS 0x00000c00 /* ASPM Support */
+#define PCI_EXP_LNKCAP_ASPM_L0S 0x00000400 /* ASPM L0s Support */
+#define PCI_EXP_LNKCAP_ASPM_L1 0x00000800 /* ASPM L1 Support */
#define PCI_EXP_LNKCAP_L0SEL 0x00007000 /* L0s Exit Latency */
#define PCI_EXP_LNKCAP_L1EL 0x00038000 /* L1 Exit Latency */
#define PCI_EXP_LNKCAP_CLKPM 0x00040000 /* Clock Power Management */
--
2.25.1
