linux-kernel - [PATCH 12/12] pcie: qcom: Set PCIE MRRS and MPS to 256B

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Date:   Fri, 20 Mar 2020 19:34:54 +0100
From:   Ansuel Smith <ansuelsmth@...il.com>
To:     Stanimir Varbanov <svarbanov@...sol.com>
Cc:     Sriram Palanisamy <gpalan@...eaurora.org>,
        Ansuel Smith <ansuelsmth@...il.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Andrew Murray <amurray@...goodpenguin.co.uk>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        linux-arm-msm@...r.kernel.org, linux-pci@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 12/12] pcie: qcom: Set PCIE MRRS and MPS to 256B

From: Sriram Palanisamy <gpalan@...eaurora.org>

Set Max Read Request Size and Max Payload Size to 256 bytes,
per chip team recommendation.

Signed-off-by: Gokul Sriram Palanisamy <gpalan@...eaurora.org>
Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 37 ++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 03130a3206b4..ad437c6f49a0 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -125,6 +125,14 @@
 
 #define PCIE20_LNK_CONTROL2_LINK_STATUS2        0xA0
 
+#define __set(v, a, b)	(((v) << (b)) & GENMASK(a, b))
+#define __mask(a, b)	(((1 << ((a) + 1)) - 1) & ~((1 << (b)) - 1))
+#define PCIE20_DEV_CAS			0x78
+#define PCIE20_MRRS_MASK		__mask(14, 12)
+#define PCIE20_MRRS(x)			__set(x, 14, 12)
+#define PCIE20_MPS_MASK			__mask(7, 5)
+#define PCIE20_MPS(x)			__set(x, 7, 5)
+
 #define DEVICE_TYPE_RC				0x4
 
 #define QCOM_PCIE_2_1_0_MAX_SUPPLY	3
@@ -1595,6 +1603,35 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 	return ret;
 }
 
+static void qcom_pcie_fixup_final(struct pci_dev *pcidev)
+{
+	int cap, err;
+	u16 ctl, reg_val;
+
+	cap = pci_pcie_cap(pcidev);
+	if (!cap)
+		return;
+
+	err = pci_read_config_word(pcidev, cap + PCI_EXP_DEVCTL, &ctl);
+
+	if (err)
+		return;
+
+	reg_val = ctl;
+
+	if (((reg_val & PCIE20_MRRS_MASK) >> 12) > 1)
+		reg_val = (reg_val & ~(PCIE20_MRRS_MASK)) | PCIE20_MRRS(0x1);
+
+	if (((ctl & PCIE20_MPS_MASK) >> 5) > 1)
+		reg_val = (reg_val & ~(PCIE20_MPS_MASK)) | PCIE20_MPS(0x1);
+
+	err = pci_write_config_word(pcidev, cap + PCI_EXP_DEVCTL, reg_val);
+
+	if (err)
+		dev_err(&pcidev->dev, "pcie config write failed %d\n", err);
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_ANY_ID, PCI_ANY_ID, qcom_pcie_fixup_final);
+
 static const struct of_device_id qcom_pcie_match[] = {
 	{ .compatible = "qcom,pcie-apq8084", .data = &ops_1_0_0 },
 	{ .compatible = "qcom,pcie-ipq8064", .data = &ops_2_1_0 },
-- 
2.25.1