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Message-Id: <20250715-pci-port-reset-v6-4-6f9cce94e7bb@oss.qualcomm.com>
Date: Tue, 15 Jul 2025 19:51:07 +0530
From: Manivannan Sadhasivam via B4 Relay <devnull+manivannan.sadhasivam.oss.qualcomm.com@...nel.org>
To: Bjorn Helgaas <bhelgaas@...gle.com>,
Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
Oliver O'Halloran <oohall@...il.com>, Will Deacon <will@...nel.org>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Krzysztof Wilczyński <kwilczynski@...nel.org>,
Manivannan Sadhasivam <mani@...nel.org>, Rob Herring <robh@...nel.org>,
Heiko Stuebner <heiko@...ech.de>, Philipp Zabel <p.zabel@...gutronix.de>
Cc: linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org, linux-arm-kernel@...ts.infradead.org,
linux-arm-msm@...r.kernel.org, linux-rockchip@...ts.infradead.org,
Niklas Cassel <cassel@...nel.org>,
Wilfred Mallawa <wilfred.mallawa@....com>,
Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>,
mani@...nel.org, Lukas Wunner <lukas@...ner.de>,
Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
Subject: [PATCH v6 4/4] PCI: dw-rockchip: Add support to reset Root Port
upon link down event
From: Wilfred Mallawa <wilfred.mallawa@....com>
The PCIe link may go down in cases like firmware crashes or unstable
connections. When this occurs, the PCIe Root Port must be reset to restore
the functionality. However, the current driver lacks link down handling,
forcing users to reboot the system to recover.
This patch implements the `reset_root_port` callback for link down handling
for Rockchip DWC PCIe host controller. In which, the RC is reset,
reconfigured and link training initiated to recover from the link down
event.
This also by extension fixes issues with sysfs initiated bus resets. In
that, currently, when a sysfs initiated bus reset is issued, the endpoint
device is non-functional after (may link up with downgraded link status).
With the link down handling support, a sysfs initiated bus reset works as
intended. Testing conducted on a ROCK5B board with an M.2 NVMe drive.
Signed-off-by: Wilfred Mallawa <wilfred.mallawa@....com>
[mani: rebased on top of the new version of reset_root_port series]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
---
drivers/pci/controller/dwc/Kconfig | 1 +
drivers/pci/controller/dwc/pcie-dw-rockchip.c | 91 ++++++++++++++++++++++++++-
2 files changed, 90 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
index ce04ee6fbd99cbcce5d2f3a75ebd72a17070b7b7..01e2650242ccc345bdd0568d08219527f00ed395 100644
--- a/drivers/pci/controller/dwc/Kconfig
+++ b/drivers/pci/controller/dwc/Kconfig
@@ -348,6 +348,7 @@ config PCIE_ROCKCHIP_DW_HOST
depends on OF
select PCIE_DW_HOST
select PCIE_ROCKCHIP_DW
+ select PCI_HOST_COMMON
help
Enables support for the DesignWare PCIe controller in the
Rockchip SoC (except RK3399) to work in host mode.
diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
index 93171a3928794915ad1e8c03c017ce0afc1f9169..8f1a34c5fbabaacbd9624048ca4c4f8dc29f2171 100644
--- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
+++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
@@ -23,6 +23,7 @@
#include <linux/reset.h>
#include "../../pci.h"
+#include "../pci-host-common.h"
#include "pcie-designware.h"
/*
@@ -84,6 +85,9 @@ struct rockchip_pcie_of_data {
const struct pci_epc_features *epc_features;
};
+static int rockchip_pcie_rc_reset_root_port(struct pci_host_bridge *bridge,
+ struct pci_dev *pdev);
+
static int rockchip_pcie_readl_apb(struct rockchip_pcie *rockchip, u32 reg)
{
return readl_relaxed(rockchip->apb_base + reg);
@@ -257,6 +261,7 @@ static int rockchip_pcie_host_init(struct dw_pcie_rp *pp)
rockchip);
rockchip_pcie_enable_l0s(pci);
+ pp->bridge->reset_root_port = rockchip_pcie_rc_reset_root_port;
return 0;
}
@@ -448,6 +453,7 @@ static irqreturn_t rockchip_pcie_rc_sys_irq_thread(int irq, void *arg)
struct dw_pcie *pci = &rockchip->pci;
struct dw_pcie_rp *pp = &pci->pp;
struct device *dev = pci->dev;
+ struct pci_dev *port;
u32 reg;
reg = rockchip_pcie_readl_apb(rockchip, PCIE_CLIENT_INTR_STATUS_MISC);
@@ -456,6 +462,14 @@ static irqreturn_t rockchip_pcie_rc_sys_irq_thread(int irq, void *arg)
dev_dbg(dev, "PCIE_CLIENT_INTR_STATUS_MISC: %#x\n", reg);
dev_dbg(dev, "LTSSM_STATUS: %#x\n", rockchip_pcie_get_ltssm(rockchip));
+ if (reg & PCIE_LINK_REQ_RST_NOT_INT) {
+ dev_dbg(dev, "hot reset or link-down reset\n");
+ for_each_pci_bridge(port, pp->bridge->bus) {
+ if (pci_pcie_type(port) == PCI_EXP_TYPE_ROOT_PORT)
+ pci_host_handle_link_down(port);
+ }
+ }
+
if (reg & PCIE_RDLH_LINK_UP_CHGED) {
if (rockchip_pcie_link_up(pci)) {
dev_dbg(dev, "Received Link up event. Starting enumeration!\n");
@@ -537,8 +551,8 @@ static int rockchip_pcie_configure_rc(struct platform_device *pdev,
return ret;
}
- /* unmask DLL up/down indicator */
- val = HIWORD_UPDATE(PCIE_RDLH_LINK_UP_CHGED, 0);
+ /* unmask DLL up/down indicator and hot reset/link-down reset irq */
+ val = HIWORD_UPDATE(PCIE_RDLH_LINK_UP_CHGED | PCIE_LINK_REQ_RST_NOT_INT, 0);
rockchip_pcie_writel_apb(rockchip, val, PCIE_CLIENT_INTR_MASK_MISC);
return ret;
@@ -689,6 +703,79 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
return ret;
}
+static int rockchip_pcie_rc_reset_root_port(struct pci_host_bridge *bridge,
+ struct pci_dev *pdev)
+{
+ struct pci_bus *bus = bridge->bus;
+ struct dw_pcie_rp *pp = bus->sysdata;
+ struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+ struct rockchip_pcie *rockchip = to_rockchip_pcie(pci);
+ struct device *dev = rockchip->pci.dev;
+ u32 val;
+ int ret;
+
+ dw_pcie_stop_link(pci);
+ clk_bulk_disable_unprepare(rockchip->clk_cnt, rockchip->clks);
+ rockchip_pcie_phy_deinit(rockchip);
+
+ ret = reset_control_assert(rockchip->rst);
+ if (ret)
+ return ret;
+
+ ret = rockchip_pcie_phy_init(rockchip);
+ if (ret)
+ goto disable_regulator;
+
+ ret = reset_control_deassert(rockchip->rst);
+ if (ret)
+ goto deinit_phy;
+
+ ret = rockchip_pcie_clk_init(rockchip);
+ if (ret)
+ goto deinit_phy;
+
+ ret = pp->ops->init(pp);
+ if (ret) {
+ dev_err(dev, "Host init failed: %d\n", ret);
+ goto deinit_clk;
+ }
+
+ /* LTSSM enable control mode */
+ val = HIWORD_UPDATE_BIT(PCIE_LTSSM_ENABLE_ENHANCE);
+ rockchip_pcie_writel_apb(rockchip, val, PCIE_CLIENT_HOT_RESET_CTRL);
+
+ rockchip_pcie_writel_apb(rockchip, PCIE_CLIENT_RC_MODE, PCIE_CLIENT_GENERAL_CON);
+
+ ret = dw_pcie_setup_rc(pp);
+ if (ret) {
+ dev_err(dev, "Failed to setup RC: %d\n", ret);
+ goto deinit_clk;
+ }
+
+ /* unmask DLL up/down indicator and hot reset/link-down reset irq */
+ val = HIWORD_UPDATE(PCIE_RDLH_LINK_UP_CHGED | PCIE_LINK_REQ_RST_NOT_INT, 0);
+ rockchip_pcie_writel_apb(rockchip, val, PCIE_CLIENT_INTR_MASK_MISC);
+
+ ret = dw_pcie_start_link(pci);
+ if (ret)
+ goto deinit_clk;
+
+ /* Ignore errors, the link may come up later */
+ dw_pcie_wait_for_link(pci);
+ dev_dbg(dev, "Root Port reset completed\n");
+ return ret;
+
+deinit_clk:
+ clk_bulk_disable_unprepare(rockchip->clk_cnt, rockchip->clks);
+deinit_phy:
+ rockchip_pcie_phy_deinit(rockchip);
+disable_regulator:
+ if (rockchip->vpcie3v3)
+ regulator_disable(rockchip->vpcie3v3);
+
+ return ret;
+}
+
static const struct rockchip_pcie_of_data rockchip_pcie_rc_of_data_rk3568 = {
.mode = DW_PCIE_RC_TYPE,
};
--
2.45.2
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