linux-kernel - [PATCH v3 3/3] PCI: brcmstb: Set PCIe transaction completion timeout

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Date:   Wed, 19 Apr 2023 12:57:20 -0400
From:   Jim Quinlan <jim2101024@...il.com>
To:     linux-pci@...r.kernel.org,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Cyril Brulebois <kibi@...ian.org>,
        Phil Elwell <phil@...pberrypi.com>,
        bcm-kernel-feedback-list@...adcom.com, jim2101024@...il.com,
        james.quinlan@...adcom.com
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Rob Herring <robh@...nel.org>,
        linux-rpi-kernel@...ts.infradead.org (moderated list:BROADCOM
        BCM2711/BCM2835 ARM ARCHITECTURE),
        linux-arm-kernel@...ts.infradead.org (moderated list:BROADCOM
        BCM2711/BCM2835 ARM ARCHITECTURE),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v3 3/3] PCI: brcmstb: Set PCIe transaction completion timeout

Since the STB PCIe HW will cause a CPU abort on a PCIe transaction
completion timeout abort, we might as well extend the default timeout
limit.  Further, different devices and systems may requires a larger or
smaller amount commensurate with their L1SS exit time, so the property
"brcm,completion-timeout-us" may be used to set a custom timeout value.

Tested-by: Florian Fainelli <f.fainelli@...il.com>
Signed-off-by: Jim Quinlan <jim2101024@...il.com>
---
 drivers/pci/controller/pcie-brcmstb.c | 30 +++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index c4b076ea5180..c2cb683447ac 100644
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -1080,6 +1080,35 @@ static void brcm_config_clkreq(struct brcm_pcie *pcie)
 	writel(clkreq_set, pcie->base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
 }
 
+static void brcm_config_completion_timeout(struct brcm_pcie *pcie)
+{
+	/* TIMEOUT register is two registers before RGR1_SW_INIT_1 */
+	const char *fmt = "brcm,completion-timeout-us clamped to region [%u..%u]\n";
+	const unsigned int REG_OFFSET = PCIE_RGR1_SW_INIT_1(pcie) - 8;
+	const u32 timeout_us_min = 16;
+	const u32 timeout_us_max = 19884107;
+	u32 timeout_us = 1000000; /* Our default, 1 second */
+	int rval, ret;
+
+	ret = of_property_read_u32(pcie->np, "brcm,completion-timeout-us",
+				   &timeout_us);
+	if (ret && ret != -EINVAL)
+		dev_err(pcie->dev, "malformed/invalid 'brcm,completion-timeout-us'\n");
+
+	/* If needed, clamp the requested timeout value and issue a warning */
+	if (timeout_us < timeout_us_min) {
+		timeout_us = timeout_us_min;
+		dev_warn(pcie->dev, fmt, timeout_us_min, timeout_us_max);
+	} else if (timeout_us > timeout_us_max) {
+		timeout_us = timeout_us_max;
+		dev_warn(pcie->dev, fmt, timeout_us_min, timeout_us_max);
+	}
+
+	/* Each unit in timeout register is 1/216,000,000 seconds */
+	rval = 216 * timeout_us;
+	writel(rval, pcie->base + REG_OFFSET);
+}
+
 static int brcm_pcie_start_link(struct brcm_pcie *pcie)
 {
 	struct device *dev = pcie->dev;
@@ -1110,6 +1139,7 @@ static int brcm_pcie_start_link(struct brcm_pcie *pcie)
 		return -ENODEV;
 	}
 
+	brcm_config_completion_timeout(pcie);
 	brcm_config_clkreq(pcie);
 
 	if (pcie->gen)
-- 
2.17.1