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PCI: stm32: Fix LTSSM EP race with start link

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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: 151f3d29ba ("PCI: stm32-ep: Add PCIe Endpoint support for STM32MP25")
Signed-off-by: Christian Bruel <christian.bruel@foss.st.com>
[mani: added fixes tag]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
[bhelgaas: wrap line]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20251114-perst_ep-v1-1-e7976317a890@foss.st.com
This commit is contained in:
Christian Bruel 2025-11-14 08:45:52 +01:00 committed by Bjorn Helgaas
parent 3a86608788
commit fa81d60990
1 changed files with 8 additions and 31 deletions
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39
drivers/pci/controller/dwc/pcie-stm32-ep.c
View File

@ -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: