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Tue, 28 Jan 2025 01:38:09 -0800 (PST) X-Google-Smtp-Source: AGHT+IELjHRrH1DA2cW0F8TVuPax9KYYfQkpneMo280DA/WRw8LZiZvNU1VaNAFZkLi0rVseiSnFJQ== X-Received: by 2002:a17:90b:3a05:b0:2ee:ed1c:e451 with SMTP id 98e67ed59e1d1-2f782cb083dmr66476710a91.15.1738057089391; Tue, 28 Jan 2025 01:38:09 -0800 (PST) Received: from hu-krichai-hyd.qualcomm.com ([202.46.23.25]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2f7ffa456absm9749501a91.2.2025.01.28.01.38.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jan 2025 01:38:09 -0800 (PST) From: Krishna Chaitanya Chundru Date: Tue, 28 Jan 2025 15:07:42 +0530 Subject: [PATCH v5 4/4] PCI: dwc: Add support for configuring lane equalization presets Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250128-preset_v2-v5-4-4d230d956f8c@oss.qualcomm.com> References: <20250128-preset_v2-v5-0-4d230d956f8c@oss.qualcomm.com> In-Reply-To: <20250128-preset_v2-v5-0-4d230d956f8c@oss.qualcomm.com> To: Rob Herring , Krzysztof Kozlowski , Conor Dooley , Bjorn Helgaas , Jingoo Han , Manivannan Sadhasivam , Lorenzo Pieralisi , =?utf-8?q?Krzysztof_Wilczy=C5=84?= =?utf-8?q?ski?= Cc: linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, konrad.dybcio@oss.qualcomm.com, quic_mrana@quicinc.com, quic_vbadigan@quicinc.com, Bjorn Andersson , Konrad Dybcio , Krishna Chaitanya Chundru X-Mailer: b4 0.14.1 X-Developer-Signature: v=1; a=ed25519-sha256; t=1738057065; l=4585; i=krishna.chundru@oss.qualcomm.com; s=20230907; h=from:subject:message-id; bh=3GLMUInncPOildJhljSbunLgceyGqCV+SYyFKStTklU=; b=qHlTKa0AShwpSvWJ0qQN32ORdr062CGGFRcChgoEZ8X80dOO2an4W+V5v0gBffldkbho0I3ft aM6ldVc1rWYCq+xQBO2VU3MUGj5Tp6915hOeu4LdWlKiHLAshFKZ3Ur X-Developer-Key: i=krishna.chundru@oss.qualcomm.com; a=ed25519; pk=10CL2pdAKFyzyOHbfSWHCD0X0my7CXxj8gJScmn1FAg= X-Proofpoint-GUID: 6gIR97_c3JcarmcLqa-kSEQyAbFeSHBF X-Proofpoint-ORIG-GUID: 6gIR97_c3JcarmcLqa-kSEQyAbFeSHBF X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-01-28_03,2025-01-27_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 mlxlogscore=999 impostorscore=0 clxscore=1015 spamscore=0 phishscore=0 priorityscore=1501 bulkscore=0 suspectscore=0 mlxscore=0 lowpriorityscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2411120000 definitions=main-2501280074 PCIe equalization presets are predefined settings used to optimize signal integrity by compensating for signal loss and distortion in high-speed data transmission. Based upon the number of lanes and the data rate supported, write the preset data read from the device tree in to the lane equalization control registers. Signed-off-by: Krishna Chaitanya Chundru --- drivers/pci/controller/dwc/pcie-designware-host.c | 41 +++++++++++++++++++++++ drivers/pci/controller/dwc/pcie-designware.h | 3 ++ include/uapi/linux/pci_regs.h | 3 ++ 3 files changed, 47 insertions(+) diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c index 2cd0acbf9e18..f458b4c70053 100644 --- a/drivers/pci/controller/dwc/pcie-designware-host.c +++ b/drivers/pci/controller/dwc/pcie-designware-host.c @@ -507,6 +507,10 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp) if (pci->num_lanes < 1) pci->num_lanes = dw_pcie_link_get_max_link_width(pci); + ret = of_pci_get_equalization_presets(dev, &pp->presets, pci->num_lanes); + if (ret) + goto err_free_msi; + /* * Allocate the resource for MSG TLP before programming the iATU * outbound window in dw_pcie_setup_rc(). Since the allocation depends @@ -802,6 +806,42 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp) return 0; } +static void dw_pcie_program_presets(struct dw_pcie *pci, u8 cap_id, u8 lane_eq_offset, + u8 lane_reg_size, u8 *presets, u8 num_lanes) +{ + u32 cap; + int i; + + cap = dw_pcie_find_ext_capability(pci, cap_id); + if (!cap) + return; + + /* + * Write preset values to the registers byte-by-byte for the given + * number of lanes and register size. + */ + for (i = 0; i < num_lanes * lane_reg_size; i++) + dw_pcie_writeb_dbi(pci, cap + lane_eq_offset + i, presets[i]); +} + +static void dw_pcie_config_presets(struct dw_pcie_rp *pp) +{ + struct dw_pcie *pci = to_dw_pcie_from_pp(pp); + enum pci_bus_speed speed = pcie_link_speed[pci->max_link_speed]; + + /* For data rate of 8 GT/S each lane equalization control is 16bits wide */ + if (speed >= PCIE_SPEED_8_0GT && pp->presets.eq_presets_8gts[0] != PCI_EQ_RESV) + dw_pcie_program_presets(pci, PCI_EXT_CAP_ID_SECPCI, PCI_SECPCI_LE_CTRL, + 0x2, (u8 *)pp->presets.eq_presets_8gts, pci->num_lanes); + + /* For data rate of 16 GT/S each lane equalization control is 8bits wide */ + if (speed >= PCIE_SPEED_16_0GT && + pp->presets.eq_presets_Ngts[EQ_PRESET_TYPE_16GTS][0] != PCI_EQ_RESV) + dw_pcie_program_presets(pci, PCI_EXT_CAP_ID_PL_16GT, PCI_PL_16GT_LE_CTRL, + 0x1, pp->presets.eq_presets_Ngts[EQ_PRESET_TYPE_16GTS], + pci->num_lanes); +} + int dw_pcie_setup_rc(struct dw_pcie_rp *pp) { struct dw_pcie *pci = to_dw_pcie_from_pp(pp); @@ -855,6 +895,7 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp) PCI_COMMAND_MASTER | PCI_COMMAND_SERR; dw_pcie_writel_dbi(pci, PCI_COMMAND, val); + dw_pcie_config_presets(pp); /* * If the platform provides its own child bus config accesses, it means * the platform uses its own address translation component rather than diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h index 500e793c9361..b12b33944df4 100644 --- a/drivers/pci/controller/dwc/pcie-designware.h +++ b/drivers/pci/controller/dwc/pcie-designware.h @@ -25,6 +25,8 @@ #include #include +#include "../../pci.h" + /* DWC PCIe IP-core versions (native support since v4.70a) */ #define DW_PCIE_VER_365A 0x3336352a #define DW_PCIE_VER_460A 0x3436302a @@ -379,6 +381,7 @@ struct dw_pcie_rp { bool use_atu_msg; int msg_atu_index; struct resource *msg_res; + struct pci_eq_presets presets; }; struct dw_pcie_ep_ops { diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h index 12323b3334a9..68fc8873bc60 100644 --- a/include/uapi/linux/pci_regs.h +++ b/include/uapi/linux/pci_regs.h @@ -1118,6 +1118,9 @@ #define PCI_DLF_CAP 0x04 /* Capabilities Register */ #define PCI_DLF_EXCHANGE_ENABLE 0x80000000 /* Data Link Feature Exchange Enable */ +/* Secondary PCIe Capability 8.0 GT/s */ +#define PCI_SECPCI_LE_CTRL 0x0c /* Lane Equalization Control Register */ + /* Physical Layer 16.0 GT/s */ #define PCI_PL_16GT_LE_CTRL 0x20 /* Lane Equalization Control Register */ #define PCI_PL_16GT_LE_CTRL_DSP_TX_PRESET_MASK 0x0000000F