linux-kernel - [PATCH V8 4/5] PCI/ASPM: save power on values during bridge init

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Date:   Sat,  8 Apr 2017 00:55:50 -0400
From:   Sinan Kaya <okaya@...eaurora.org>
To:     linux-pci@...r.kernel.org, timur@...eaurora.org
Cc:     mayurkumar.patel@...el.com, linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Sinan Kaya <okaya@...eaurora.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Rajat Jain <rajatja@...gle.com>,
        Yinghai Lu <yinghai@...nel.org>,
        David Daney <david.daney@...ium.com>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Julia Lawall <Julia.Lawall@...6.fr>,
        linux-kernel@...r.kernel.org
Subject: [PATCH V8 4/5] PCI/ASPM: save power on values during bridge init

Now that we added a hook to be called from device_add, save the
default values from the HW registers early in the boot for further
reuse during hot device add/remove operations.

If the link is down during boot, assume that we want to enable L0s
and L1 following hotplug insertion as well as L1SS if supported.

Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=194895
Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
---
 drivers/pci/pcie/aspm.c | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index e33f84b..c7da087 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -505,8 +505,10 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
 	 */
 	if (dwreg.support & upreg.support & PCIE_LINK_STATE_L0S)
 		link->aspm_support |= ASPM_STATE_L0S;
-	if (dwreg.enabled & PCIE_LINK_STATE_L0S)
+	if (dwreg.enabled & PCIE_LINK_STATE_L0S) {
 		link->aspm_enabled |= ASPM_STATE_L0S_UP;
+		link->aspm_default |= ASPM_STATE_L0S_UP;
+	}
 	if (upreg.enabled & PCIE_LINK_STATE_L0S)
 		link->aspm_enabled |= ASPM_STATE_L0S_DW;
 	link->latency_up.l0s = calc_l0s_latency(upreg.latency_encoding_l0s);
@@ -542,9 +544,6 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
 	if (link->aspm_support & ASPM_STATE_L1SS)
 		aspm_calc_l1ss_info(link, &upreg, &dwreg);
 
-	/* Save default state */
-	link->aspm_default = link->aspm_enabled;
-
 	/* Setup initial capable state. Will be updated later */
 	link->aspm_capable = link->aspm_support;
 	/*
@@ -835,11 +834,38 @@ static int pci_aspm_init_downstream(struct pci_dev *pdev)
 static int pci_aspm_init_upstream(struct pci_dev *pdev)
 {
 	struct pcie_link_state *link;
+	struct aspm_register_info upreg;
+	u16 lnk_status;
+	bool ret;
 
 	link = alloc_pcie_link_state(pdev);
 	if (!link)
 		return -ENOMEM;
 
+	pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
+	ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
+
+	if (ret) {
+		pcie_get_aspm_reg(pdev, &upreg);
+		if (upreg.enabled & PCIE_LINK_STATE_L0S)
+			link->aspm_default |= ASPM_STATE_L0S_DW;
+		if (upreg.enabled & PCIE_LINK_STATE_L1)
+			link->aspm_default |= ASPM_STATE_L1;
+		if (upreg.l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_1)
+			link->aspm_default |= ASPM_STATE_L1_1;
+		if (upreg.l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_2)
+			link->aspm_default |= ASPM_STATE_L1_2;
+		if (upreg.l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_1)
+			link->aspm_default |= ASPM_STATE_L1_1_PCIPM;
+		if (upreg.l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_2)
+			link->aspm_default |= ASPM_STATE_L1_2_PCIPM;
+	} else {
+		if (!pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_L1SS))
+			link->aspm_default = ASPM_STATE_L0S | ASPM_STATE_L1;
+		else
+			link->aspm_default = ASPM_STATE_ALL;
+	}
+
 	return 0;
 }
 
-- 
1.9.1