From: Mrinmay Sarkar quic_msarkar@quicinc.com
[ Upstream commit 1d648bf79d4dca909f242b1a0cdc458e4f9d0253 ]
Due to some hardware changes, SA8775P has set the NO_SNOOP attribute in its TLP for all the PCIe controllers. NO_SNOOP attribute when set, the requester is indicating that no cache coherency issue exist for the addressed memory on the endpoint i.e., memory is not cached. But in reality, requester cannot assume this unless there is a complete control/visibility over the addressed memory on the endpoint.
And worst case, if the memory is cached on the endpoint, it may lead to memory corruption issues. It should be noted that the caching of memory on the endpoint is not solely dependent on the NO_SNOOP attribute in TLP.
So to avoid the corruption, this patch overrides the NO_SNOOP attribute by setting the PCIE_PARF_NO_SNOOP_OVERIDE register. This patch is not needed for other upstream supported platforms since they do not set NO_SNOOP attribute by default.
8775 has IP version 1.34.0 so introduce a new cfg(cfg_1_34_0) for this platform. Assign override_no_snoop flag into struct qcom_pcie_cfg and set it true in cfg_1_34_0 and enable cache snooping if this particular flag is true.
Link: https://lore.kernel.org/linux-pci/1710166298-27144-2-git-send-email-quic_msa... Signed-off-by: Mrinmay Sarkar quic_msarkar@quicinc.com Signed-off-by: Krzysztof Wilczyński kwilczynski@kernel.org [bhelgaas: wrap comments to fit in 80 columns] Signed-off-by: Bjorn Helgaas bhelgaas@google.com Reviewed-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/controller/dwc/pcie-qcom.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c index 14772edcf0d34..7fa1fe5a29e3d 100644 --- a/drivers/pci/controller/dwc/pcie-qcom.c +++ b/drivers/pci/controller/dwc/pcie-qcom.c @@ -51,6 +51,7 @@ #define PARF_SID_OFFSET 0x234 #define PARF_BDF_TRANSLATE_CFG 0x24c #define PARF_SLV_ADDR_SPACE_SIZE 0x358 +#define PARF_NO_SNOOP_OVERIDE 0x3d4 #define PARF_DEVICE_TYPE 0x1000 #define PARF_BDF_TO_SID_TABLE_N 0x2000 #define PARF_BDF_TO_SID_CFG 0x2c00 @@ -118,6 +119,10 @@ /* PARF_LTSSM register fields */ #define LTSSM_EN BIT(8)
+/* PARF_NO_SNOOP_OVERIDE register fields */ +#define WR_NO_SNOOP_OVERIDE_EN BIT(1) +#define RD_NO_SNOOP_OVERIDE_EN BIT(3) + /* PARF_DEVICE_TYPE register fields */ #define DEVICE_TYPE_RC 0x4
@@ -231,8 +236,15 @@ struct qcom_pcie_ops { int (*config_sid)(struct qcom_pcie *pcie); };
+ /** + * struct qcom_pcie_cfg - Per SoC config struct + * @ops: qcom PCIe ops structure + * @override_no_snoop: Override NO_SNOOP attribute in TLP to enable cache + * snooping + */ struct qcom_pcie_cfg { const struct qcom_pcie_ops *ops; + bool override_no_snoop; bool no_l0s; };
@@ -986,6 +998,12 @@ 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) { + const struct qcom_pcie_cfg *pcie_cfg = pcie->cfg; + + if (pcie_cfg->override_no_snoop) + writel(WR_NO_SNOOP_OVERIDE_EN | RD_NO_SNOOP_OVERIDE_EN, + pcie->parf + PARF_NO_SNOOP_OVERIDE); + qcom_pcie_clear_aspm_l0s(pcie->pci); qcom_pcie_clear_hpc(pcie->pci);
@@ -1366,6 +1384,11 @@ static const struct qcom_pcie_cfg cfg_1_9_0 = { .ops = &ops_1_9_0, };
+static const struct qcom_pcie_cfg cfg_1_34_0 = { + .ops = &ops_1_9_0, + .override_no_snoop = true, +}; + static const struct qcom_pcie_cfg cfg_2_1_0 = { .ops = &ops_2_1_0, }; @@ -1667,7 +1690,7 @@ static const struct of_device_id qcom_pcie_match[] = { { .compatible = "qcom,pcie-msm8996", .data = &cfg_2_3_2 }, { .compatible = "qcom,pcie-qcs404", .data = &cfg_2_4_0 }, { .compatible = "qcom,pcie-sa8540p", .data = &cfg_sc8280xp }, - { .compatible = "qcom,pcie-sa8775p", .data = &cfg_1_9_0}, + { .compatible = "qcom,pcie-sa8775p", .data = &cfg_1_34_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_sc8280xp },