From 74ce81de32feb468fa4477bee6516ed553a4d973 Mon Sep 17 00:00:00 2001 From: Vidya Sagar Date: Wed, 25 Mar 2026 00:37:48 +0530 Subject: [PATCH] PCI: tegra194: Disable direct speed change for Endpoint mode [ Upstream commit 976f6763f57970388bcd7118931f33f447916927 ] Pre-silicon simulation showed the controller operating in Endpoint mode initiating link speed change after completing Secondary Bus Reset. Ideally, the Root Port or the Switch Downstream Port should initiate the link speed change post SBR, not the Endpoint. So, as per the hardware team recommendation, disable direct speed change for the Endpoint mode to prevent it from initiating speed change after the physical layer link is up at Gen1, leaving speed change ownership with the host. Fixes: c57247f940e8 ("PCI: tegra: Add support for PCIe endpoint mode in Tegra194") Signed-off-by: Vidya Sagar Signed-off-by: Manikanta Maddireddy [mani: commit log] Signed-off-by: Manivannan Sadhasivam Signed-off-by: Bjorn Helgaas Tested-by: Jon Hunter Reviewed-by: Jon Hunter Reviewed-by: Vidya Sagar Link: https://patch.msgid.link/20260324190755.1094879-8-mmaddireddy@nvidia.com Signed-off-by: Sasha Levin --- drivers/pci/controller/dwc/pcie-tegra194.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c index d5f48aa6bf5a..3fd89a983f6d 100644 --- a/drivers/pci/controller/dwc/pcie-tegra194.c +++ b/drivers/pci/controller/dwc/pcie-tegra194.c @@ -1774,6 +1774,10 @@ static void pex_ep_event_pex_rst_deassert(struct tegra_pcie_dw *pcie) reset_control_deassert(pcie->core_rst); + val = dw_pcie_readl_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL); + val &= ~PORT_LOGIC_SPEED_CHANGE; + dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, val); + if (pcie->update_fc_fixup) { val = dw_pcie_readl_dbi(pci, CFG_TIMER_CTRL_MAX_FUNC_NUM_OFF); val |= 0x1 << CFG_TIMER_CTRL_ACK_NAK_SHIFT;