diff options
| author | Manikanta Maddireddy <mmaddireddy@nvidia.com> | 2026-03-25 00:37:44 +0530 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2026-04-08 16:56:34 -0500 |
| commit | 9fa0c242f8d7acf1b124d4462d18f4023573ac1c (patch) | |
| tree | 4fa321e9550d85bf4898f751858fefcca255ec61 /drivers/pci/controller | |
| parent | 74dd8efe4d6cead433162147333af989a568aac7 (diff) | |
| download | lwn-9fa0c242f8d7acf1b124d4462d18f4023573ac1c.tar.gz lwn-9fa0c242f8d7acf1b124d4462d18f4023573ac1c.zip | |
PCI: tegra194: Disable LTSSM after transition to Detect on surprise link down
After the link reaches a Detect-related LTSSM state, disable LTSSM so it
does not keep toggling between Polling and Detect. Do this by polling for
the Detect state first, then clearing APPL_CTRL_LTSSM_EN in both
tegra_pcie_dw_pme_turnoff() and pex_ep_event_pex_rst_assert().
Fixes: 56e15a238d92 ("PCI: tegra: Add Tegra194 PCIe support")
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://patch.msgid.link/20260324190755.1094879-4-mmaddireddy@nvidia.com
Diffstat (limited to 'drivers/pci/controller')
| -rw-r--r-- | drivers/pci/controller/dwc/pcie-tegra194.c | 29 |
1 files changed, 16 insertions, 13 deletions
diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c index 94113b2e3308..b38dbd02214b 100644 --- a/drivers/pci/controller/dwc/pcie-tegra194.c +++ b/drivers/pci/controller/dwc/pcie-tegra194.c @@ -1594,14 +1594,6 @@ static void tegra_pcie_dw_pme_turnoff(struct tegra_pcie_dw *pcie) data &= ~APPL_PINMUX_PEX_RST; appl_writel(pcie, data, APPL_PINMUX); - /* - * Some cards do not go to detect state even after de-asserting - * PERST#. So, de-assert LTSSM to bring link to detect state. - */ - data = readl(pcie->appl_base + APPL_CTRL); - data &= ~APPL_CTRL_LTSSM_EN; - writel(data, pcie->appl_base + APPL_CTRL); - err = readl_poll_timeout(pcie->appl_base + APPL_DEBUG, data, ((data & APPL_DEBUG_LTSSM_STATE_MASK) == LTSSM_STATE_DETECT_QUIET) || ((data & APPL_DEBUG_LTSSM_STATE_MASK) == LTSSM_STATE_DETECT_ACT) || @@ -1610,6 +1602,14 @@ static void tegra_pcie_dw_pme_turnoff(struct tegra_pcie_dw *pcie) LTSSM_DELAY_US, LTSSM_TIMEOUT_US); if (err) dev_info(pcie->dev, "LTSSM state: 0x%x detect timeout: %d\n", data, err); + + /* + * Deassert LTSSM state to stop the state toggling between + * Polling and Detect. + */ + data = readl(pcie->appl_base + APPL_CTRL); + data &= ~APPL_CTRL_LTSSM_EN; + writel(data, pcie->appl_base + APPL_CTRL); } /* * DBI registers may not be accessible after this as PLL-E would be @@ -1683,11 +1683,6 @@ static void pex_ep_event_pex_rst_assert(struct tegra_pcie_dw *pcie) if (pcie->ep_state == EP_STATE_DISABLED) return; - /* Disable LTSSM */ - val = appl_readl(pcie, APPL_CTRL); - val &= ~APPL_CTRL_LTSSM_EN; - appl_writel(pcie, val, APPL_CTRL); - ret = readl_poll_timeout(pcie->appl_base + APPL_DEBUG, val, ((val & APPL_DEBUG_LTSSM_STATE_MASK) == LTSSM_STATE_DETECT_QUIET) || ((val & APPL_DEBUG_LTSSM_STATE_MASK) == LTSSM_STATE_DETECT_ACT) || @@ -1698,6 +1693,14 @@ static void pex_ep_event_pex_rst_assert(struct tegra_pcie_dw *pcie) if (ret) dev_info(pcie->dev, "LTSSM state: 0x%x detect timeout: %d\n", val, ret); + /* + * Deassert LTSSM state to stop the state toggling between + * Polling and Detect. + */ + val = appl_readl(pcie, APPL_CTRL); + val &= ~APPL_CTRL_LTSSM_EN; + appl_writel(pcie, val, APPL_CTRL); + reset_control_assert(pcie->core_rst); tegra_pcie_disable_phy(pcie); |