From fa81d6099007728cae39c6f937d83903bbddab5e Mon Sep 17 00:00:00 2001 From: Christian Bruel Date: Fri, 14 Nov 2025 08:45:52 +0100 Subject: [PATCH] PCI: stm32: Fix LTSSM EP race with start link If the host has deasserted PERST# and started link training before the link is started on EP side, enabling LTSSM before the endpoint registers are initialized in the perst_irq handler results in probing incorrect values. Thus, wait for the PERST# level-triggered interrupt to start link training at the end of initialization and cleanup the stm32_pcie_[start stop]_link functions. Fixes: 151f3d29baf4 ("PCI: stm32-ep: Add PCIe Endpoint support for STM32MP25") Signed-off-by: Christian Bruel [mani: added fixes tag] Signed-off-by: Manivannan Sadhasivam [bhelgaas: wrap line] Signed-off-by: Bjorn Helgaas Link: https://patch.msgid.link/20251114-perst_ep-v1-1-e7976317a890@foss.st.com --- drivers/pci/controller/dwc/pcie-stm32-ep.c | 39 +++++----------------- 1 file changed, 8 insertions(+), 31 deletions(-) diff --git a/drivers/pci/controller/dwc/pcie-stm32-ep.c b/drivers/pci/controller/dwc/pcie-stm32-ep.c index 3400c7cd2d88..faa6433a784f 100644 --- a/drivers/pci/controller/dwc/pcie-stm32-ep.c +++ b/drivers/pci/controller/dwc/pcie-stm32-ep.c @@ -37,36 +37,9 @@ static void stm32_pcie_ep_init(struct dw_pcie_ep *ep) dw_pcie_ep_reset_bar(pci, bar); } -static int stm32_pcie_enable_link(struct dw_pcie *pci) -{ - struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci); - - regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR, - STM32MP25_PCIECR_LTSSM_EN, - STM32MP25_PCIECR_LTSSM_EN); - - return dw_pcie_wait_for_link(pci); -} - -static void stm32_pcie_disable_link(struct dw_pcie *pci) -{ - struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci); - - regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR, STM32MP25_PCIECR_LTSSM_EN, 0); -} - static int stm32_pcie_start_link(struct dw_pcie *pci) { struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci); - int ret; - - dev_dbg(pci->dev, "Enable link\n"); - - ret = stm32_pcie_enable_link(pci); - if (ret) { - dev_err(pci->dev, "PCIe cannot establish link: %d\n", ret); - return ret; - } enable_irq(stm32_pcie->perst_irq); @@ -77,11 +50,7 @@ static void stm32_pcie_stop_link(struct dw_pcie *pci) { struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci); - dev_dbg(pci->dev, "Disable link\n"); - disable_irq(stm32_pcie->perst_irq); - - stm32_pcie_disable_link(pci); } static int stm32_pcie_raise_irq(struct dw_pcie_ep *ep, u8 func_no, @@ -152,6 +121,9 @@ static void stm32_pcie_perst_assert(struct dw_pcie *pci) dev_dbg(dev, "PERST asserted by host\n"); + regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR, + STM32MP25_PCIECR_LTSSM_EN, 0); + pci_epc_deinit_notify(ep->epc); stm32_pcie_disable_resources(stm32_pcie); @@ -192,6 +164,11 @@ static void stm32_pcie_perst_deassert(struct dw_pcie *pci) pci_epc_init_notify(ep->epc); + /* Enable link training */ + regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR, + STM32MP25_PCIECR_LTSSM_EN, + STM32MP25_PCIECR_LTSSM_EN); + return; err_disable_resources: -- 2.47.3