linux-kernel - [PATCH v3 06/11] PCI: brcmstb: Avoid turn off of bridge reset

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Message-ID: <20241014130710.413-7-svarbanov@suse.de>
Date: Mon, 14 Oct 2024 16:07:05 +0300
From: Stanimir Varbanov <svarbanov@...e.de>
To: linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-rpi-kernel@...ts.infradead.org,
	linux-pci@...r.kernel.org,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>
Cc: Thomas Gleixner <tglx@...utronix.de>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	Jim Quinlan <jim2101024@...il.com>,
	Nicolas Saenz Julienne <nsaenz@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	kw@...ux.com,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Andrea della Porta <andrea.porta@...e.com>,
	Phil Elwell <phil@...pberrypi.com>,
	Jonathan Bell <jonathan@...pberrypi.com>,
	Stanimir Varbanov <svarbanov@...e.de>
Subject: [PATCH v3 06/11] PCI: brcmstb: Avoid turn off of bridge reset

On PCIe turn off avoid shutdown of bridge reset,
by introducing a quirk flag.

Signed-off-by: Stanimir Varbanov <svarbanov@...e.de>
---
v2 -> v3:
 - Added more descriptive comment on CFG_QUIRK_AVOID_BRIDGE_SHUTDOWN quirk.

 drivers/pci/controller/pcie-brcmstb.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index b76c16287f37..757a1646d53c 100644
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -234,10 +234,20 @@ struct inbound_win {
 	u64 cpu_addr;
 };
 
+/*
+ * The RESCAL block is tied to PCIe controller #1, regardless of the number of
+ * controllers, and turning off PCIe controller #1 prevents access to the RESCAL
+ * register blocks, therefore not other controller can access this register
+ * space, and depending upon the bus fabric we may get a timeout (UBUS/GISB),
+ * or a hang (AXI).
+ */
+#define CFG_QUIRK_AVOID_BRIDGE_SHUTDOWN		BIT(0)
+
 struct pcie_cfg_data {
 	const int *offsets;
 	const enum pcie_soc_base soc_base;
 	const bool has_phy;
+	const u32 quirks;
 	u8 num_inbound_wins;
 	int (*perst_set)(struct brcm_pcie *pcie, u32 val);
 	int (*bridge_sw_init_set)(struct brcm_pcie *pcie, u32 val);
@@ -290,6 +300,7 @@ struct brcm_pcie {
 	struct subdev_regulators *sr;
 	bool			ep_wakeup_capable;
 	bool			has_phy;
+	u32			quirks;
 	u8			num_inbound_wins;
 };
 
@@ -1539,8 +1550,9 @@ static int brcm_pcie_turn_off(struct brcm_pcie *pcie)
 	u32p_replace_bits(&tmp, 1, PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK);
 	writel(tmp, base + HARD_DEBUG(pcie));
 
-	/* Shutdown PCIe bridge */
-	ret = pcie->bridge_sw_init_set(pcie, 1);
+	if (!(pcie->quirks & CFG_QUIRK_AVOID_BRIDGE_SHUTDOWN))
+		/* Shutdown PCIe bridge */
+		ret = pcie->bridge_sw_init_set(pcie, 1);
 
 	return ret;
 }
@@ -1854,6 +1866,7 @@ static int brcm_pcie_probe(struct platform_device *pdev)
 	pcie->perst_set = data->perst_set;
 	pcie->bridge_sw_init_set = data->bridge_sw_init_set;
 	pcie->has_phy = data->has_phy;
+	pcie->quirks = data->quirks;
 	pcie->num_inbound_wins = data->num_inbound_wins;
 
 	pcie->base = devm_platform_ioremap_resource(pdev, 0);
-- 
2.43.0