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From: Bjorn Helgaas <helgaas@kernel.org>
To: "Saheed O . Bolarinwa" <refactormyself@gmail.com>
Cc: Puranjay Mohan <puranjay12@gmail.com>,
	Rajat Jain <rajatja@google.com>,
	Kai-Heng Feng <kai.heng.feng@canonical.com>,
	Yicong Yang <yangyicong@hisilicon.com>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	linux-pci@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>
Subject: [PATCH v3 02/12] PCI/ASPM: Move LTR path check to where it's used
Date: Thu, 15 Oct 2020 14:30:29 -0500	[thread overview]
Message-ID: <20201015193039.12585-3-helgaas@kernel.org> (raw)
In-Reply-To: <20201015193039.12585-1-helgaas@kernel.org>

From: Bjorn Helgaas <bhelgaas@google.com>

pcie_get_aspm_reg() mostly reads ASPM-related registers, but in some cases
it also updates the value read from PCI_L1SS_CAP based on LTR properties.

Move this update to the point where the value is used to make the code more
readable.

No functional change intended, although previously we could clear
PCI_L1SS_CAP_ASPM_L1_2 for both ends of the link, and now we'll only do it
for the downstream end of a link.  This shouldn't matter because we always
test that bit by ANDing l1ss_cap for the upstream and downstream ends.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/pcie/aspm.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 237a423e53ae..386b45eb79ba 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -418,14 +418,6 @@ static void pcie_get_aspm_reg(struct pci_dev *pdev,
 		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,
@@ -612,7 +604,14 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
 	link->latency_up.l1 = calc_l1_latency(upreg.latency_encoding_l1);
 	link->latency_dw.l1 = calc_l1_latency(dwreg.latency_encoding_l1);
 
-	/* Setup L1 substate */
+	/* Setup L1 substate
+	 * 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)
+		dwreg.l1ss_cap &= ~PCI_L1SS_CAP_ASPM_L1_2;
+
 	if (upreg.l1ss_cap & dwreg.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)
-- 
2.25.1


  parent reply	other threads:[~2020-10-15 19:30 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-15 19:30 [PATCH v3 00/12] PCI/ASPM: Cleanup Bjorn Helgaas
2020-10-15 19:30 ` [PATCH v3 01/12] PCI/ASPM: Move pci_clear_and_set_dword() earlier Bjorn Helgaas
2020-10-15 19:30 ` Bjorn Helgaas [this message]
2020-10-15 19:30 ` [PATCH v3 03/12] PCI/ASPM: Use 'parent' and 'child' for readability Bjorn Helgaas
2020-10-15 19:30 ` [PATCH v3 04/12] PCI/ASPM: Remove struct aspm_register_info.support Bjorn Helgaas
2020-10-15 19:30 ` [PATCH v3 05/12] PCI/ASPM: Remove struct aspm_register_info.enabled Bjorn Helgaas
2020-10-15 19:30 ` [PATCH v3 06/12] PCI/ASPM: Remove struct aspm_register_info.latency_encoding Bjorn Helgaas
2020-10-15 19:30 ` [PATCH v3 07/12] PCI/ASPM: Remove struct aspm_register_info.l1ss_cap_ptr Bjorn Helgaas
2020-10-15 19:30 ` [PATCH v3 08/12] PCI/ASPM: Remove struct aspm_register_info.l1ss_ctl2 (unused) Bjorn Helgaas
2020-10-15 19:30 ` [PATCH v3 09/12] PCI/ASPM: Remove struct aspm_register_info.l1ss_ctl1 Bjorn Helgaas
2020-10-15 19:30 ` [PATCH v3 10/12] PCI/ASPM: Pass L1SS Capabilities value, not struct aspm_register_info Bjorn Helgaas
2020-10-15 19:30 ` [PATCH v3 11/12] PCI/ASPM: Remove struct aspm_register_info.l1ss_cap Bjorn Helgaas
2020-10-15 19:30 ` [PATCH v3 12/12] PCI/ASPM: Remove struct pcie_link_state.l1ss Bjorn Helgaas
2020-10-16 20:59   ` Bjorn Helgaas

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