6.12-stable review patch. If anyone has any objections, please let me know.
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From: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org
[ Upstream commit 40e2125381dc11379112485e3eefdd25c6df5375 ]
Currently, the endpoint cleanup function dw_pcie_ep_cleanup() and EPF deinit notify function pci_epc_deinit_notify() are called during the execution of pex_ep_event_pex_rst_assert() i.e., when the host has asserted PERST#. But quickly after this step, refclk will also be disabled by the host.
All of the tegra194 endpoint SoCs supported as of now depend on the refclk from the host for keeping the controller operational. Due to this limitation, any access to the hardware registers in the absence of refclk will result in a whole endpoint crash. Unfortunately, most of the controller cleanups require accessing the hardware registers (like eDMA cleanup performed in dw_pcie_ep_cleanup(), etc...). So these cleanup functions can cause the crash in the endpoint SoC once host asserts PERST#.
One way to address this issue is by generating the refclk in the endpoint itself and not depending on the host. But that is not always possible as some of the endpoint designs do require the endpoint to consume refclk from the host.
Thus, fix this crash by moving the controller cleanups to the start of the pex_ep_event_pex_rst_deassert() function. This function is called whenever the host has deasserted PERST# and it is guaranteed that the refclk would be active at this point. So at the start of this function (after enabling resources) the controller cleanup can be performed. Once finished, rest of the code execution for PERST# deassert can continue as usual.
Fixes: 473b2cf9c4d1 ("PCI: endpoint: Introduce 'epc_deinit' event and notify the EPF drivers") Fixes: 570d7715eed8 ("PCI: dwc: ep: Introduce dw_pcie_ep_cleanup() API for drivers supporting PERST#") Link: https://lore.kernel.org/r/20240817-pci-qcom-ep-cleanup-v1-2-d6b958226559@lin... Signed-off-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org Signed-off-by: Krzysztof Wilczyński kwilczynski@kernel.org Cc: Jonathan Hunter jonathanh@nvidia.com Cc: Thierry Reding thierry.reding@gmail.com Cc: Vidya Sagar vidyas@nvidia.com Cc: linux-tegra@vger.kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/controller/dwc/pcie-tegra194.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c index c1394f2ab63ff..ced3b7e7bdade 100644 --- a/drivers/pci/controller/dwc/pcie-tegra194.c +++ b/drivers/pci/controller/dwc/pcie-tegra194.c @@ -1704,9 +1704,6 @@ static void pex_ep_event_pex_rst_assert(struct tegra_pcie_dw *pcie) if (ret) dev_err(pcie->dev, "Failed to go Detect state: %d\n", ret);
- pci_epc_deinit_notify(pcie->pci.ep.epc); - dw_pcie_ep_cleanup(&pcie->pci.ep); - reset_control_assert(pcie->core_rst);
tegra_pcie_disable_phy(pcie); @@ -1785,6 +1782,10 @@ static void pex_ep_event_pex_rst_deassert(struct tegra_pcie_dw *pcie) goto fail_phy; }
+ /* Perform cleanup that requires refclk */ + pci_epc_deinit_notify(pcie->pci.ep.epc); + dw_pcie_ep_cleanup(&pcie->pci.ep); + /* Clear any stale interrupt statuses */ appl_writel(pcie, 0xFFFFFFFF, APPL_INTR_STATUS_L0); appl_writel(pcie, 0xFFFFFFFF, APPL_INTR_STATUS_L1_0_0);