Merge branch 'pci/aspm'

- Remove struct aspm_register_info (Saheed O. Bolarinwa)

- Remove struct pcie_link_state.l1ss (Saheed O. Bolarinwa)

* pci/aspm:
  PCI/ASPM: Remove struct pcie_link_state.l1ss
  PCI/ASPM: Remove struct aspm_register_info.l1ss_cap
  PCI/ASPM: Pass L1SS Capabilities value, not struct aspm_register_info
  PCI/ASPM: Remove struct aspm_register_info.l1ss_ctl1
  PCI/ASPM: Remove struct aspm_register_info.l1ss_ctl2 (unused)
  PCI/ASPM: Remove struct aspm_register_info.l1ss_cap_ptr
  PCI/ASPM: Remove struct aspm_register_info.latency_encoding
  PCI/ASPM: Remove struct aspm_register_info.enabled
  PCI/ASPM: Remove struct aspm_register_info.support
  PCI/ASPM: Use 'parent' and 'child' for readability
  PCI/ASPM: Move LTR path check to where it's used
  PCI/ASPM: Move pci_clear_and_set_dword() earlier

2 files changed, 146 insertions, 151 deletions

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 253c30cc1967..ac0557a305af 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -74,14 +74,6 @@ struct pcie_link_state {
 	 * has one slot under it, so at most there are 8 functions.
 	 */
 	struct aspm_latency acceptable[8];
-
-	/* L1 PM Substate info */
-	struct {
-		u32 up_cap_ptr;		/* L1SS cap ptr in upstream dev */
-		u32 dw_cap_ptr;		/* L1SS cap ptr in downstream dev */
-		u32 ctl1;		/* value to be programmed in ctl1 */
-		u32 ctl2;		/* value to be programmed in ctl2 */
-	} l1ss;
 };
 
 static int aspm_disabled, aspm_force;
@@ -308,8 +300,10 @@ static void pcie_aspm_configure_common_clock(struct pcie_link_state *link)
 }
 
 /* Convert L0s latency encoding to ns */
-static u32 calc_l0s_latency(u32 encoding)
+static u32 calc_l0s_latency(u32 lnkcap)
 {
+	u32 encoding = (lnkcap & PCI_EXP_LNKCAP_L0SEL) >> 12;
+
 	if (encoding == 0x7)
 		return (5 * 1000);	/* > 4us */
 	return (64 << encoding);
@@ -324,8 +318,10 @@ static u32 calc_l0s_acceptable(u32 encoding)
 }
 
 /* Convert L1 latency encoding to ns */
-static u32 calc_l1_latency(u32 encoding)
+static u32 calc_l1_latency(u32 lnkcap)
 {
+	u32 encoding = (lnkcap & PCI_EXP_LNKCAP_L1EL) >> 15;
+
 	if (encoding == 0x7)
 		return (65 * 1000);	/* > 64us */
 	return (1000 << encoding);
@@ -380,58 +376,6 @@ 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;
-
-	/* L1 substates */
-	u32 l1ss_cap_ptr;
-	u32 l1ss_cap;
-	u32 l1ss_ctl1;
-	u32 l1ss_ctl2;
-};
-
-static void pcie_get_aspm_reg(struct pci_dev *pdev,
-			      struct aspm_register_info *info)
-{
-	u16 reg16;
-	u32 reg32;
-
-	pcie_capability_read_dword(pdev, PCI_EXP_LNKCAP, &reg32);
-	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, &reg16);
-	info->enabled = reg16 & PCI_EXP_LNKCTL_ASPMC;
-
-	/* Read L1 PM substate capabilities */
-	info->l1ss_cap = info->l1ss_ctl1 = info->l1ss_ctl2 = 0;
-	info->l1ss_cap_ptr = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_L1SS);
-	if (!info->l1ss_cap_ptr)
-		return;
-	pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CAP,
-			      &info->l1ss_cap);
-	if (!(info->l1ss_cap & PCI_L1SS_CAP_L1_PM_SS)) {
-		info->l1ss_cap = 0;
-		return;
-	}
-
-	/*
-	 * If we don't have LTR for the entire path from the Root Complex
-	 * to this device, we can't use ASPM L1.2 because it relies on the
-	 * LTR_L1.2_THRESHOLD.  See PCIe r4.0, secs 5.5.4, 6.18.
-	 */
-	if (!pdev->ltr_path)
-		info->l1ss_cap &= ~PCI_L1SS_CAP_ASPM_L1_2;
-
-	pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CTL1,
-			      &info->l1ss_ctl1);
-	pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CTL2,
-			      &info->l1ss_ctl2);
-}
-
 static void pcie_aspm_check_latency(struct pci_dev *endpoint)
 {
 	u32 latency, l1_switch_latency = 0;
@@ -493,39 +437,49 @@ static struct pci_dev *pci_function_0(struct pci_bus *linkbus)
 	return NULL;
 }
 
+static void pci_clear_and_set_dword(struct pci_dev *pdev, int pos,
+				    u32 clear, u32 set)
+{
+	u32 val;
+
+	pci_read_config_dword(pdev, pos, &val);
+	val &= ~clear;
+	val |= set;
+	pci_write_config_dword(pdev, pos, val);
+}
+
 /* Calculate L1.2 PM substate timing parameters */
 static void aspm_calc_l1ss_info(struct pcie_link_state *link,
-				struct aspm_register_info *upreg,
-				struct aspm_register_info *dwreg)
+				u32 parent_l1ss_cap, u32 child_l1ss_cap)
 {
+	struct pci_dev *child = link->downstream, *parent = link->pdev;
 	u32 val1, val2, scale1, scale2;
 	u32 t_common_mode, t_power_on, l1_2_threshold, scale, value;
-
-	link->l1ss.up_cap_ptr = upreg->l1ss_cap_ptr;
-	link->l1ss.dw_cap_ptr = dwreg->l1ss_cap_ptr;
-	link->l1ss.ctl1 = link->l1ss.ctl2 = 0;
+	u32 ctl1 = 0, ctl2 = 0;
+	u32 pctl1, pctl2, cctl1, cctl2;
+	u32 pl1_2_enables, cl1_2_enables;
 
 	if (!(link->aspm_support & ASPM_STATE_L1_2_MASK))
 		return;
 
 	/* Choose the greater of the two Port Common_Mode_Restore_Times */
-	val1 = (upreg->l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
-	val2 = (dwreg->l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
+	val1 = (parent_l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
+	val2 = (child_l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
 	t_common_mode = max(val1, val2);
 
 	/* Choose the greater of the two Port T_POWER_ON times */
-	val1   = (upreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
-	scale1 = (upreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
-	val2   = (dwreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
-	scale2 = (dwreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
-
-	if (calc_l1ss_pwron(link->pdev, scale1, val1) >
-	    calc_l1ss_pwron(link->downstream, scale2, val2)) {
-		link->l1ss.ctl2 |= scale1 | (val1 << 3);
-		t_power_on = calc_l1ss_pwron(link->pdev, scale1, val1);
+	val1   = (parent_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
+	scale1 = (parent_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
+	val2   = (child_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
+	scale2 = (child_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
+
+	if (calc_l1ss_pwron(parent, scale1, val1) >
+	    calc_l1ss_pwron(child, scale2, val2)) {
+		ctl2 |= scale1 | (val1 << 3);
+		t_power_on = calc_l1ss_pwron(parent, scale1, val1);
 	} else {
-		link->l1ss.ctl2 |= scale2 | (val2 << 3);
-		t_power_on = calc_l1ss_pwron(link->downstream, scale2, val2);
+		ctl2 |= scale2 | (val2 << 3);
+		t_power_on = calc_l1ss_pwron(child, scale2, val2);
 	}
 
 	/*
@@ -540,14 +494,60 @@ static void aspm_calc_l1ss_info(struct pcie_link_state *link,
 	 */
 	l1_2_threshold = 2 + 4 + t_common_mode + t_power_on;
 	encode_l12_threshold(l1_2_threshold, &scale, &value);
-	link->l1ss.ctl1 |= t_common_mode << 8 | scale << 29 | value << 16;
+	ctl1 |= t_common_mode << 8 | scale << 29 | value << 16;
+
+	pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CTL1, &pctl1);
+	pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CTL2, &pctl2);
+	pci_read_config_dword(child, child->l1ss + PCI_L1SS_CTL1, &cctl1);
+	pci_read_config_dword(child, child->l1ss + PCI_L1SS_CTL2, &cctl2);
+
+	if (ctl1 == pctl1 && ctl1 == cctl1 &&
+	    ctl2 == pctl2 && ctl2 == cctl2)
+		return;
+
+	/* Disable L1.2 while updating.  See PCIe r5.0, sec 5.5.4, 7.8.3.3 */
+	pl1_2_enables = pctl1 & PCI_L1SS_CTL1_L1_2_MASK;
+	cl1_2_enables = cctl1 & PCI_L1SS_CTL1_L1_2_MASK;
+
+	if (pl1_2_enables || cl1_2_enables) {
+		pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1,
+					PCI_L1SS_CTL1_L1_2_MASK, 0);
+		pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
+					PCI_L1SS_CTL1_L1_2_MASK, 0);
+	}
+
+	/* Program T_POWER_ON times in both ports */
+	pci_write_config_dword(parent, parent->l1ss + PCI_L1SS_CTL2, ctl2);
+	pci_write_config_dword(child, child->l1ss + PCI_L1SS_CTL2, ctl2);
+
+	/* Program Common_Mode_Restore_Time in upstream device */
+	pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
+				PCI_L1SS_CTL1_CM_RESTORE_TIME, ctl1);
+
+	/* Program LTR_L1.2_THRESHOLD time in both ports */
+	pci_clear_and_set_dword(parent,	parent->l1ss + PCI_L1SS_CTL1,
+				PCI_L1SS_CTL1_LTR_L12_TH_VALUE |
+				PCI_L1SS_CTL1_LTR_L12_TH_SCALE, ctl1);
+	pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1,
+				PCI_L1SS_CTL1_LTR_L12_TH_VALUE |
+				PCI_L1SS_CTL1_LTR_L12_TH_SCALE, ctl1);
+
+	if (pl1_2_enables || cl1_2_enables) {
+		pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1, 0,
+					pl1_2_enables);
+		pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1, 0,
+					cl1_2_enables);
+	}
 }
 
 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;
+	u16 parent_lnkctl, child_lnkctl;
+	u32 parent_l1ss_cap, child_l1ss_cap;
+	u32 parent_l1ss_ctl1 = 0, child_l1ss_ctl1 = 0;
 	struct pci_bus *linkbus = parent->subordinate;
-	struct aspm_register_info upreg, dwreg;
 
 	if (blacklist) {
 		/* Set enabled/disable so that we will disable ASPM later */
@@ -556,26 +556,28 @@ 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_get_aspm_reg(parent, &upreg);
-	pcie_get_aspm_reg(child, &dwreg);
+	pcie_capability_read_dword(parent, PCI_EXP_LNKCAP, &parent_lnkcap);
+	pcie_capability_read_dword(child, PCI_EXP_LNKCAP, &child_lnkcap);
+	pcie_capability_read_word(parent, PCI_EXP_LNKCTL, &parent_lnkctl);
+	pcie_capability_read_word(child, PCI_EXP_LNKCTL, &child_lnkctl);
 
 	/*
 	 * Setup L0s state
@@ -584,44 +586,71 @@ 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)
+
+	if (child_lnkctl & PCI_EXP_LNKCTL_ASPM_L0S)
 		link->aspm_enabled |= ASPM_STATE_L0S_UP;
-	if (upreg.enabled & PCIE_LINK_STATE_L0S)
+	if (parent_lnkctl & PCI_EXP_LNKCTL_ASPM_L0S)
 		link->aspm_enabled |= ASPM_STATE_L0S_DW;
-	link->latency_up.l0s = calc_l0s_latency(upreg.latency_encoding_l0s);
-	link->latency_dw.l0s = calc_l0s_latency(dwreg.latency_encoding_l0s);
+	link->latency_up.l0s = calc_l0s_latency(parent_lnkcap);
+	link->latency_dw.l0s = calc_l0s_latency(child_lnkcap);
 
 	/* 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)
+
+	if (parent_lnkctl & child_lnkctl & PCI_EXP_LNKCTL_ASPM_L1)
 		link->aspm_enabled |= ASPM_STATE_L1;
-	link->latency_up.l1 = calc_l1_latency(upreg.latency_encoding_l1);
-	link->latency_dw.l1 = calc_l1_latency(dwreg.latency_encoding_l1);
+	link->latency_up.l1 = calc_l1_latency(parent_lnkcap);
+	link->latency_dw.l1 = calc_l1_latency(child_lnkcap);
 
 	/* Setup L1 substate */
-	if (upreg.l1ss_cap & dwreg.l1ss_cap & PCI_L1SS_CAP_ASPM_L1_1)
+	pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CAP,
+			      &parent_l1ss_cap);
+	pci_read_config_dword(child, child->l1ss + PCI_L1SS_CAP,
+			      &child_l1ss_cap);
+
+	if (!(parent_l1ss_cap & PCI_L1SS_CAP_L1_PM_SS))
+		parent_l1ss_cap = 0;
+	if (!(child_l1ss_cap & PCI_L1SS_CAP_L1_PM_SS))
+		child_l1ss_cap = 0;
+
+	/*
+	 * If we don't have LTR for the entire path from the Root Complex
+	 * to this device, we can't use ASPM L1.2 because it relies on the
+	 * LTR_L1.2_THRESHOLD.  See PCIe r4.0, secs 5.5.4, 6.18.
+	 */
+	if (!child->ltr_path)
+		child_l1ss_cap &= ~PCI_L1SS_CAP_ASPM_L1_2;
+
+	if (parent_l1ss_cap & child_l1ss_cap & PCI_L1SS_CAP_ASPM_L1_1)
 		link->aspm_support |= ASPM_STATE_L1_1;
-	if (upreg.l1ss_cap & dwreg.l1ss_cap & PCI_L1SS_CAP_ASPM_L1_2)
+	if (parent_l1ss_cap & child_l1ss_cap & PCI_L1SS_CAP_ASPM_L1_2)
 		link->aspm_support |= ASPM_STATE_L1_2;
-	if (upreg.l1ss_cap & dwreg.l1ss_cap & PCI_L1SS_CAP_PCIPM_L1_1)
+	if (parent_l1ss_cap & child_l1ss_cap & PCI_L1SS_CAP_PCIPM_L1_1)
 		link->aspm_support |= ASPM_STATE_L1_1_PCIPM;
-	if (upreg.l1ss_cap & dwreg.l1ss_cap & PCI_L1SS_CAP_PCIPM_L1_2)
+	if (parent_l1ss_cap & child_l1ss_cap & PCI_L1SS_CAP_PCIPM_L1_2)
 		link->aspm_support |= ASPM_STATE_L1_2_PCIPM;
 
-	if (upreg.l1ss_ctl1 & dwreg.l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_1)
+	if (parent_l1ss_cap)
+		pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
+				      &parent_l1ss_ctl1);
+	if (child_l1ss_cap)
+		pci_read_config_dword(child, child->l1ss + PCI_L1SS_CTL1,
+				      &child_l1ss_ctl1);
+
+	if (parent_l1ss_ctl1 & child_l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_1)
 		link->aspm_enabled |= ASPM_STATE_L1_1;
-	if (upreg.l1ss_ctl1 & dwreg.l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_2)
+	if (parent_l1ss_ctl1 & child_l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_2)
 		link->aspm_enabled |= ASPM_STATE_L1_2;
-	if (upreg.l1ss_ctl1 & dwreg.l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_1)
+	if (parent_l1ss_ctl1 & child_l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_1)
 		link->aspm_enabled |= ASPM_STATE_L1_1_PCIPM;
-	if (upreg.l1ss_ctl1 & dwreg.l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_2)
+	if (parent_l1ss_ctl1 & child_l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_2)
 		link->aspm_enabled |= ASPM_STATE_L1_2_PCIPM;
 
 	if (link->aspm_support & ASPM_STATE_L1SS)
-		aspm_calc_l1ss_info(link, &upreg, &dwreg);
+		aspm_calc_l1ss_info(link, parent_l1ss_cap, child_l1ss_cap);
 
 	/* Save default state */
 	link->aspm_default = link->aspm_enabled;
@@ -651,24 +680,11 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
 	}
 }
 
-static void pci_clear_and_set_dword(struct pci_dev *pdev, int pos,
-				    u32 clear, u32 set)
-{
-	u32 val;
-
-	pci_read_config_dword(pdev, pos, &val);
-	val &= ~clear;
-	val |= set;
-	pci_write_config_dword(pdev, pos, val);
-}
-
 /* Configure the ASPM L1 substates */
 static void pcie_config_aspm_l1ss(struct pcie_link_state *link, u32 state)
 {
 	u32 val, enable_req;
 	struct pci_dev *child = link->downstream, *parent = link->pdev;
-	u32 up_cap_ptr = link->l1ss.up_cap_ptr;
-	u32 dw_cap_ptr = link->l1ss.dw_cap_ptr;
 
 	enable_req = (link->aspm_enabled ^ state) & state;
 
@@ -686,9 +702,9 @@ static void pcie_config_aspm_l1ss(struct pcie_link_state *link, u32 state)
 	 */
 
 	/* Disable all L1 substates */
-	pci_clear_and_set_dword(child, dw_cap_ptr + PCI_L1SS_CTL1,
+	pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1,
 				PCI_L1SS_CTL1_L1SS_MASK, 0);
-	pci_clear_and_set_dword(parent, up_cap_ptr + PCI_L1SS_CTL1,
+	pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
 				PCI_L1SS_CTL1_L1SS_MASK, 0);
 	/*
 	 * If needed, disable L1, and it gets enabled later
@@ -701,30 +717,6 @@ static void pcie_config_aspm_l1ss(struct pcie_link_state *link, u32 state)
 						   PCI_EXP_LNKCTL_ASPM_L1, 0);
 	}
 
-	if (enable_req & ASPM_STATE_L1_2_MASK) {
-
-		/* Program T_POWER_ON times in both ports */
-		pci_write_config_dword(parent, up_cap_ptr + PCI_L1SS_CTL2,
-				       link->l1ss.ctl2);
-		pci_write_config_dword(child, dw_cap_ptr + PCI_L1SS_CTL2,
-				       link->l1ss.ctl2);
-
-		/* Program Common_Mode_Restore_Time in upstream device */
-		pci_clear_and_set_dword(parent, up_cap_ptr + PCI_L1SS_CTL1,
-					PCI_L1SS_CTL1_CM_RESTORE_TIME,
-					link->l1ss.ctl1);
-
-		/* Program LTR_L1.2_THRESHOLD time in both ports */
-		pci_clear_and_set_dword(parent,	up_cap_ptr + PCI_L1SS_CTL1,
-					PCI_L1SS_CTL1_LTR_L12_TH_VALUE |
-					PCI_L1SS_CTL1_LTR_L12_TH_SCALE,
-					link->l1ss.ctl1);
-		pci_clear_and_set_dword(child, dw_cap_ptr + PCI_L1SS_CTL1,
-					PCI_L1SS_CTL1_LTR_L12_TH_VALUE |
-					PCI_L1SS_CTL1_LTR_L12_TH_SCALE,
-					link->l1ss.ctl1);
-	}
-
 	val = 0;
 	if (state & ASPM_STATE_L1_1)
 		val |= PCI_L1SS_CTL1_ASPM_L1_1;
@@ -736,9 +728,9 @@ static void pcie_config_aspm_l1ss(struct pcie_link_state *link, u32 state)
 		val |= PCI_L1SS_CTL1_PCIPM_L1_2;
 
 	/* Enable what we need to enable */
-	pci_clear_and_set_dword(parent, up_cap_ptr + PCI_L1SS_CTL1,
+	pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
 				PCI_L1SS_CTL1_L1SS_MASK, val);
-	pci_clear_and_set_dword(child, dw_cap_ptr + PCI_L1SS_CTL1,
+	pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1,
 				PCI_L1SS_CTL1_L1SS_MASK, val);
 }
 
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 03d37128a24f..06f6bbcd8131 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2106,6 +2106,9 @@ static void pci_configure_ltr(struct pci_dev *dev)
 	if (!pci_is_pcie(dev))
 		return;
 
+	/* Read L1 PM substate capabilities */
+	dev->l1ss = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS);
+
 	pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
 	if (!(cap & PCI_EXP_DEVCAP2_LTR))
 		return;