Re: [PATCH v4 3/5] PCI: qcom: Disable ASPM L0s for sc8280xp, sa8540p and sa8295p

Manivannan Sadhasivam
2024-03-06T10:57:14Z

On Wed, Mar 06, 2024 at 10:56:49AM +0100, Johan Hovold wrote:
> Commit 9f4f3dfad8cf ("PCI: qcom: Enable ASPM for platforms supporting
> 1.9.0 ops") started enabling ASPM unconditionally when the hardware
> claims to support it. This triggers Correctable Errors for some PCIe
> devices on machines like the Lenovo ThinkPad X13s when L0s is enabled,
> which could indicate an incomplete driver ASPM implementation or that
> the hardware does in fact not support L0s.
>
> This has now been confirmed by Qualcomm to be the case for sc8280xp and
> its derivate platforms (e.g. sa8540p and sa8295p). Specifically, the PHY
> configuration used on these platforms is not correctly tuned for L0s and
> there is currently no updated configuration available.
>
> Add a new flag to the driver configuration data and use it to disable
> ASPM L0s on sc8280xp, sa8540p and sa8295p for now.
>
> Note that only the 1.9.0 ops enable ASPM currently.
>
> Fixes: 9f4f3dfad8cf ("PCI: qcom: Enable ASPM for platforms supporting 1.9.0 ops")
> Cc: stable@vger.kernel.org # 6.7
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

- Mani

> ---
> drivers/pci/controller/dwc/pcie-qcom.c | 31 ++++++++++++++++++++++++--
> 1 file changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 2ce2a3bd932b..9f83a1611a20 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -229,6 +229,7 @@ struct qcom_pcie_ops {
>
> struct qcom_pcie_cfg {
> const struct qcom_pcie_ops *ops;
> + bool no_l0s;
> };
>
> struct qcom_pcie {
> @@ -272,6 +273,26 @@ static int qcom_pcie_start_link(struct dw_pcie *pci)
> return 0;
> }
>
> +static void qcom_pcie_clear_aspm_l0s(struct dw_pcie *pci)
> +{
> + struct qcom_pcie *pcie = to_qcom_pcie(pci);
> + u16 offset;
> + u32 val;
> +
> + if (!pcie->cfg->no_l0s)
> + return;
> +
> + offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> +
> + dw_pcie_dbi_ro_wr_en(pci);
> +
> + val = readl(pci->dbi_base + offset + PCI_EXP_LNKCAP);
> + val &= ~PCI_EXP_LNKCAP_ASPM_L0S;
> + writel(val, pci->dbi_base + offset + PCI_EXP_LNKCAP);
> +
> + dw_pcie_dbi_ro_wr_dis(pci);
> +}
> +
> static void qcom_pcie_clear_hpc(struct dw_pcie *pci)
> {
> u16 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> @@ -961,6 +982,7 @@ static int qcom_pcie_init_2_7_0(struct qcom_pcie *pcie)
>
> static int qcom_pcie_post_init_2_7_0(struct qcom_pcie *pcie)
> {
> + qcom_pcie_clear_aspm_l0s(pcie->pci);
> qcom_pcie_clear_hpc(pcie->pci);
>
> return 0;
> @@ -1358,6 +1380,11 @@ static const struct qcom_pcie_cfg cfg_2_9_0 = {
> .ops = &ops_2_9_0,
> };
>
> +static const struct qcom_pcie_cfg cfg_sc8280xp = {
> + .ops = &ops_1_9_0,
> + .no_l0s = true,
> +};
> +
> static const struct dw_pcie_ops dw_pcie_ops = {
> .link_up = qcom_pcie_link_up,
> .start_link = qcom_pcie_start_link,
> @@ -1629,11 +1656,11 @@ static const struct of_device_id qcom_pcie_match[] = {
> { .compatible = "qcom,pcie-ipq8074-gen3", .data = &cfg_2_9_0 },
> { .compatible = "qcom,pcie-msm8996", .data = &cfg_2_3_2 },
> { .compatible = "qcom,pcie-qcs404", .data = &cfg_2_4_0 },
> - { .compatible = "qcom,pcie-sa8540p", .data = &cfg_1_9_0 },
> + { .compatible = "qcom,pcie-sa8540p", .data = &cfg_sc8280xp },
> { .compatible = "qcom,pcie-sa8775p", .data = &cfg_1_9_0},
> { .compatible = "qcom,pcie-sc7280", .data = &cfg_1_9_0 },
> { .compatible = "qcom,pcie-sc8180x", .data = &cfg_1_9_0 },
> - { .compatible = "qcom,pcie-sc8280xp", .data = &cfg_1_9_0 },
> + { .compatible = "qcom,pcie-sc8280xp", .data = &cfg_sc8280xp },
> { .compatible = "qcom,pcie-sdm845", .data = &cfg_2_7_0 },
> { .compatible = "qcom,pcie-sdx55", .data = &cfg_1_9_0 },
> { .compatible = "qcom,pcie-sm8150", .data = &cfg_1_9_0 },
> --
> 2.43.0
>

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