linux-kernel - [PATCH v3 01/15] PCI: dwc: Add more verbose link-up message

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20220610084444.14549-2-Sergey.Semin@baikalelectronics.ru>
Date:   Fri, 10 Jun 2022 11:44:29 +0300
From:   Serge Semin <Sergey.Semin@...kalelectronics.ru>
To:     Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Krzysztof Wilczyński <kw@...ux.com>
CC:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Serge Semin <fancer.lancer@...il.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        Frank Li <Frank.Li@....com>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Rob Herring <robh+dt@...nel.org>, <linux-pci@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v3 01/15] PCI: dwc: Add more verbose link-up message

Printing just "link up" isn't that much informative especially when it
comes to working with the PCI Express bus. Even if the link is up, due to
multiple reasons the bus performance can degrade to slower speeds or to
narrower width than both Root Port and its partner is capable of. In that
case it would be handy to know the link specifications as early as
possible. So let's add a more verbose message to the busy-wait link-state
method, which will contain the link speed generation and the PCIe bus
width in case if the link up state is discovered. Otherwise an error will
be printed to the system log.

Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
Reviewed-by: Rob Herring <robh@...nel.org>

---

Changelog v2:
- Test the error condition first and return straight away if it comes true.
  The typical return is better to be unindented (@Joe).
---
 drivers/pci/controller/dwc/pcie-designware.c | 22 ++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index ce01187947c9..e66d16a86168 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -524,20 +524,30 @@ void dw_pcie_disable_atu(struct dw_pcie *pci, int index,
 
 int dw_pcie_wait_for_link(struct dw_pcie *pci)
 {
+	u32 offset, val;
 	int retries;
 
 	/* Check if the link is up or not */
 	for (retries = 0; retries < LINK_WAIT_MAX_RETRIES; retries++) {
-		if (dw_pcie_link_up(pci)) {
-			dev_info(pci->dev, "Link up\n");
-			return 0;
-		}
+		if (dw_pcie_link_up(pci))
+			break;
+
 		usleep_range(LINK_WAIT_USLEEP_MIN, LINK_WAIT_USLEEP_MAX);
 	}
 
-	dev_info(pci->dev, "Phy link never came up\n");
+	if (retries >= LINK_WAIT_MAX_RETRIES) {
+		dev_err(pci->dev, "Phy link never came up\n");
+		return -ETIMEDOUT;
+	}
+
+	offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+	val = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA);
 
-	return -ETIMEDOUT;
+	dev_info(pci->dev, "PCIe Gen.%u x%u link up\n",
+		 FIELD_GET(PCI_EXP_LNKSTA_CLS, val),
+		 FIELD_GET(PCI_EXP_LNKSTA_NLW, val));
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(dw_pcie_wait_for_link);
 
-- 
2.35.1