Re: [PATCH v2 02/10] PCI: tegra194: Check core reset deassertion

[Frank Li]

On Wed, Oct 21, 2026 at 11:43:41AM +0530, Manikanta Maddireddy wrote:
> Several paths access DBI registers after deasserting the controller core
> reset. If reset_control_deassert() fails, those DBI accesses can trigger a
> CBB timeout, or setup can return success with the core still in reset.
>
> Check core reset deassertion in Root Port setup, the DLF retry path and the
> Endpoint PERST# deassert path. Unwind before DBI access when deassertion
> fails.
>
> Fixes: 56e15a238d92 ("PCI: tegra: Add Tegra194 PCIe support")
> Signed-off-by: Manikanta Maddireddy <mmaddireddy@xxxxxxxxxx>
> ---

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

> Changes V1 -> V2: None
>
>  drivers/pci/controller/dwc/pcie-tegra194.c | 23 +++++++++++++++++++---
>  1 file changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> index 6104a22d930e..89dbef83dd9e 100644
> --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> @@ -954,6 +954,7 @@ static int tegra_pcie_dw_start_link(struct dw_pcie *pci)
>  	struct tegra_pcie_dw *pcie = to_tegra_pcie(pci);
>  	struct dw_pcie_rp *pp = &pci->pp;
>  	u32 val, offset, tmp;
> +	int ret;
>  	bool retry = true;
>
>  	if (pcie->of_data->mode == DW_PCIE_EP_TYPE) {
> @@ -1009,7 +1010,12 @@ static int tegra_pcie_dw_start_link(struct dw_pcie *pci)
>  		appl_writel(pcie, val, APPL_CTRL);
>
>  		reset_control_assert(pcie->core_rst);
> -		reset_control_deassert(pcie->core_rst);
> +		ret = reset_control_deassert(pcie->core_rst);
> +		if (ret) {
> +			dev_err(pci->dev, "Failed to deassert core reset: %d\n",
> +				ret);
> +			return ret;
> +		}
>
>  		offset = dw_pcie_find_ext_capability(pci, PCI_EXT_CAP_ID_DLF);
>  		val = dw_pcie_readl_dbi(pci, offset + PCI_DLF_CAP);
> @@ -1455,10 +1461,16 @@ static int tegra_pcie_config_controller(struct tegra_pcie_dw *pcie,
>  		    pcie->atu_dma_res->start & APPL_CFG_IATU_DMA_BASE_ADDR_MASK,
>  		    APPL_CFG_IATU_DMA_BASE_ADDR);
>
> -	reset_control_deassert(pcie->core_rst);
> +	ret = reset_control_deassert(pcie->core_rst);
> +	if (ret) {
> +		dev_err(pcie->dev, "Failed to deassert core reset: %d\n", ret);
> +		goto fail_core_rst;
> +	}
>
>  	return ret;
>
> +fail_core_rst:
> +	tegra_pcie_disable_phy(pcie);
>  fail_phy:
>  	reset_control_assert(pcie->core_apb_rst);
>  fail_core_apb_rst:
> @@ -1853,7 +1865,11 @@ static void pex_ep_event_pex_rst_deassert(struct tegra_pcie_dw *pcie)
>  	      LTR_NOSNOOP_MSG_REQ;
>  	appl_writel(pcie, val, APPL_LTR_MSG_1);
>
> -	reset_control_deassert(pcie->core_rst);
> +	ret = reset_control_deassert(pcie->core_rst);
> +	if (ret) {
> +		dev_err(dev, "Failed to deassert core reset: %d\n", ret);
> +		goto fail_core_rst;
> +	}
>
>  	/* Perform cleanup that requires refclk and core reset deasserted */
>  	pci_epc_deinit_notify(pcie->pci.ep.epc);
> @@ -1927,6 +1943,7 @@ static void pex_ep_event_pex_rst_deassert(struct tegra_pcie_dw *pcie)
>
>  fail_init_complete:
>  	reset_control_assert(pcie->core_rst);
> +fail_core_rst:
>  	tegra_pcie_disable_phy(pcie);
>  fail_phy:
>  	reset_control_assert(pcie->core_apb_rst);
> --
> 2.34.1
>