linux-kernel - [PATCH v6 4/5] PCI: brcmstb: Assert PERST# on BCM2711

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Message-Id: <20230623144100.34196-5-james.quinlan@broadcom.com>
Date:   Fri, 23 Jun 2023 10:40:57 -0400
From:   Jim Quinlan <james.quinlan@...adcom.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, james.quinlan@...adcom.com
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Jim Quinlan <jim2101024@...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 v6 4/5] PCI: brcmstb: Assert PERST# on BCM2711

The current PCIe driver assumes PERST# is asserted when probe() is invoked.
Some older versions of the 2711/RPi bootloader left PERST# unasserted, as
the Raspian OS does assert PERST# on probe().  For this reason, we assert
PERST# for BCM2711 SOCs (i.e. RPi).

Signed-off-by: Jim Quinlan <james.quinlan@...adcom.com>
---
 drivers/pci/controller/pcie-brcmstb.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index fe0415a98c63..7b698a9a851e 100644
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -884,6 +884,11 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
 
 	/* Reset the bridge */
 	pcie->bridge_sw_init_set(pcie, 1);
+
+	/* Ensure that PERST# is asserted; some bootloaders may deassert it. */
+	if (pcie->type == BCM2711)
+		pcie->perst_set(pcie, 1);
+
 	usleep_range(100, 200);
 
 	/* Take the bridge out of reset */
-- 
2.17.1


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