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authorSaheed O. Bolarinwa <refactormyself@gmail.com>2021-11-19 20:37:30 +0100
committerBjorn Helgaas <bhelgaas@google.com>2021-11-19 16:46:09 -0600
commit222578dad4731cb8932471f42a0a606116ec5398 (patch)
treecbe66da90fef8dbe77435dbfe4b6b7ab4c2f4298 /drivers/pci/pcie
parent43262f001b318a0c0531e252b47bc6b07794f356 (diff)
downloadlinux-222578dad4731cb8932471f42a0a606116ec5398.tar.bz2
PCI/ASPM: Stop caching link L0s, L1 exit latencies
Previously we calculated the upstream and downstream L0s and L1 exit latencies of the link in pcie_aspm_cap_init() and cached them in struct pcie_link_state.latency_*. These values are only used in pcie_aspm_check_latency() where they are compared with the acceptable latencies on the link. This path is used when removing or changing the D state of the device, so it's relatively low frequency. To reduce the amount of per-link data we store, remove the latency_* entries from struct pcie_link_state and calculate the latencies directly where they are needed. Link: https://lore.kernel.org/r/20211119193732.12343-3-refactormyself@gmail.com Signed-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Diffstat (limited to 'drivers/pci/pcie')
-rw-r--r--drivers/pci/pcie/aspm.c28
1 files changed, 17 insertions, 11 deletions
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 6f128b654730..a7a1d59c338f 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -66,9 +66,6 @@ struct pcie_link_state {
u32 clkpm_default:1; /* Default Clock PM state by BIOS */
u32 clkpm_disable:1; /* Clock PM disabled */
- /* Exit latencies */
- struct aspm_latency latency_up; /* Upstream direction exit latency */
- struct aspm_latency latency_dw; /* Downstream direction exit latency */
/*
* Endpoint acceptable latencies. A pcie downstream port only
* has one slot under it, so at most there are 8 functions.
@@ -392,7 +389,8 @@ static void encode_l12_threshold(u32 threshold_us, u32 *scale, u32 *value)
static void pcie_aspm_check_latency(struct pci_dev *endpoint)
{
- u32 latency, l1_switch_latency = 0;
+ u32 latency, lnkcap_up, lnkcap_dw, l1_switch_latency = 0;
+ struct aspm_latency latency_up, latency_dw;
struct aspm_latency *acceptable;
struct pcie_link_state *link;
@@ -405,14 +403,26 @@ static void pcie_aspm_check_latency(struct pci_dev *endpoint)
acceptable = &link->acceptable[PCI_FUNC(endpoint->devfn)];
while (link) {
+ struct pci_dev *dev = pci_function_0(link->pdev->subordinate);
+
+ /* Read direction exit latencies */
+ pcie_capability_read_dword(link->pdev, PCI_EXP_LNKCAP,
+ &lnkcap_up);
+ pcie_capability_read_dword(dev, PCI_EXP_LNKCAP,
+ &lnkcap_dw);
+ latency_up.l0s = calc_l0s_latency(lnkcap_up);
+ latency_up.l1 = calc_l1_latency(lnkcap_up);
+ latency_dw.l0s = calc_l0s_latency(lnkcap_dw);
+ latency_dw.l1 = calc_l1_latency(lnkcap_dw);
+
/* Check upstream direction L0s latency */
if ((link->aspm_capable & ASPM_STATE_L0S_UP) &&
- (link->latency_up.l0s > acceptable->l0s))
+ (latency_up.l0s > acceptable->l0s))
link->aspm_capable &= ~ASPM_STATE_L0S_UP;
/* Check downstream direction L0s latency */
if ((link->aspm_capable & ASPM_STATE_L0S_DW) &&
- (link->latency_dw.l0s > acceptable->l0s))
+ (latency_dw.l0s > acceptable->l0s))
link->aspm_capable &= ~ASPM_STATE_L0S_DW;
/*
* Check L1 latency.
@@ -427,7 +437,7 @@ static void pcie_aspm_check_latency(struct pci_dev *endpoint)
* L1 exit latencies advertised by a device include L1
* substate latencies (and hence do not do any check).
*/
- latency = max_t(u32, link->latency_up.l1, link->latency_dw.l1);
+ latency = max_t(u32, latency_up.l1, latency_dw.l1);
if ((link->aspm_capable & ASPM_STATE_L1) &&
(latency + l1_switch_latency > acceptable->l1))
link->aspm_capable &= ~ASPM_STATE_L1;
@@ -593,8 +603,6 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
link->aspm_enabled |= ASPM_STATE_L0S_UP;
if (parent_lnkctl & PCI_EXP_LNKCTL_ASPM_L0S)
link->aspm_enabled |= ASPM_STATE_L0S_DW;
- link->latency_up.l0s = calc_l0s_latency(parent_lnkcap);
- link->latency_dw.l0s = calc_l0s_latency(child_lnkcap);
/* Setup L1 state */
if (parent_lnkcap & child_lnkcap & PCI_EXP_LNKCAP_ASPM_L1)
@@ -602,8 +610,6 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
if (parent_lnkctl & child_lnkctl & PCI_EXP_LNKCTL_ASPM_L1)
link->aspm_enabled |= ASPM_STATE_L1;
- link->latency_up.l1 = calc_l1_latency(parent_lnkcap);
- link->latency_dw.l1 = calc_l1_latency(child_lnkcap);
/* Setup L1 substate */
pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CAP,