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

From: Jim Quinlan <james.quinlan@broadcom.com>
To: linux-pci@vger.kernel.org,
	Nicolas Saenz Julienne <nsaenz@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Cyril Brulebois <kibi@debian.org>,
	Phil Elwell <phil@raspberrypi.com>,
	bcm-kernel-feedback-list@broadcom.com,
	james.quinlan@broadcom.com
Cc: "Florian Fainelli" <f.fainelli@gmail.com>,
	"Jim Quinlan" <jim2101024@gmail.com>,
	"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Rob Herring" <robh@kernel.org>,
	linux-rpi-kernel@lists.infradead.org (moderated list:BROADCOM
	BCM2711/BCM2835 ARM ARCHITECTURE),
	linux-arm-kernel@lists.infradead.org (moderated list:BROADCOM
	BCM2711/BCM2835 ARM ARCHITECTURE),
	linux-kernel@vger.kernel.org (open list)
Subject: [PATCH v6 4/5] PCI: brcmstb: Assert PERST# on BCM2711
Date: Fri, 23 Jun 2023 10:40:57 -0400	[thread overview]
Message-ID: <20230623144100.34196-5-james.quinlan@broadcom.com> (raw)
In-Reply-To: <20230623144100.34196-1-james.quinlan@broadcom.com>

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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@broadcom.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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