linux-kernel - [PATCH 11/11] PCI: mvebu: Fix reporting Data Link Layer Link Active on emulated bridge

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Message-Id: <20211221141455.30011-12-pali@kernel.org>
Date:   Tue, 21 Dec 2021 15:14:55 +0100
From:   Pali Rohár <pali@...nel.org>
To:     "Thomas Petazzoni" <thomas.petazzoni@...tlin.com>,
        "Lorenzo Pieralisi" <lorenzo.pieralisi@....com>,
        "Rob Herring" <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        "Bjorn Helgaas" <bhelgaas@...gle.com>,
        Marek Behún <kabel@...nel.org>
Cc:     linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 11/11] PCI: mvebu: Fix reporting Data Link Layer Link Active on emulated bridge

Add support for reporting PCI_EXP_LNKSTA_DLLLA bit in Link Control register
on emulated bridge via PCIE_STAT_OFF reg. Function mvebu_pcie_link_up()
already parses this register and returns if Data Link is Active or not.

Also correctly indicate DLLLA capability via PCI_EXP_LNKCAP_DLLLARC bit in
Link Control Capability register which is required for reporting DLLLA bit.

Signed-off-by: Pali Rohár <pali@...nel.org>
---
 drivers/pci/controller/pci-mvebu.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
index dffa330de174..a075ba26cff1 100644
--- a/drivers/pci/controller/pci-mvebu.c
+++ b/drivers/pci/controller/pci-mvebu.c
@@ -548,13 +548,18 @@ mvebu_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge,
 		/*
 		 * PCIe requires that the Clock Power Management capability bit
 		 * is hard-wired to zero for downstream ports but HW returns 1.
+		 * Additionally enable Data Link Layer Link Active Reporting
+		 * Capable bit as DL_Active indication is provided too.
 		 */
-		*value = mvebu_readl(port, PCIE_CAP_PCIEXP + PCI_EXP_LNKCAP) &
-			 ~PCI_EXP_LNKCAP_CLKPM;
+		*value = (mvebu_readl(port, PCIE_CAP_PCIEXP + PCI_EXP_LNKCAP) &
+			  ~PCI_EXP_LNKCAP_CLKPM) | PCI_EXP_LNKCAP_DLLLARC;
 		break;
 
 	case PCI_EXP_LNKCTL:
-		*value = mvebu_readl(port, PCIE_CAP_PCIEXP + PCI_EXP_LNKCTL);
+		/* DL_Active indication is provided via PCIE_STAT_OFF */
+		*value = mvebu_readl(port, PCIE_CAP_PCIEXP + PCI_EXP_LNKCTL) |
+			 (mvebu_pcie_link_up(port) ?
+			  (PCI_EXP_LNKSTA_DLLLA << 16) : 0);
 		break;
 
 	case PCI_EXP_SLTCTL:
-- 
2.20.1