linux-kernel - [PATCH v2 2/2] PCI: dwc: Add support to handle ZRX-DC Compliant PHYs

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Date:   Mon, 28 Oct 2019 17:46:28 +0530
From:   Anvesh Salveru <anvesh.s@...sung.com>
To:     linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     bhelgaas@...gle.com, gustavo.pimentel@...opsys.com,
        jingoohan1@...il.com, pankaj.dubey@...sung.com,
        Anvesh Salveru <anvesh.s@...sung.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Andrew Murray <andrew.murray@....com>
Subject: [PATCH v2 2/2] PCI: dwc: Add support to handle ZRX-DC Compliant
 PHYs

Many platforms use DesignWare controller but the PHY can be different in
different platforms. If the PHY is compliant to the ZRX-DC specification
it helps lower power consumption during power states.

If current data rate is 8.0 GT/s or higher and PHY is not compliant to
ZRX-DC specification, then after every 100ms link should transition to
recovery state during the low power states.

DesignWare controller provides GEN3_ZRXDC_NONCOMPL field in
GEN3_RELATED_OFF to specify about ZRX-DC compliant PHY.

Platforms with ZRX-DC compliant PHY can set "snps,phy-zrxdc-compliant"
property in controller DT node to specify this property to the controller.

CC: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
CC: Andrew Murray <andrew.murray@....com>
Signed-off-by: Anvesh Salveru <anvesh.s@...sung.com>
Signed-off-by: Pankaj Dubey <pankaj.dubey@...sung.com>
Acked-by: Gustavo Pimentel <gustavo.pimentel@...opsys.com>
---
Change in v2:
 - trivial change in patch description

 drivers/pci/controller/dwc/pcie-designware.c | 7 +++++++
 drivers/pci/controller/dwc/pcie-designware.h | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 820488dfeaed..6560d9f765d7 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -556,4 +556,11 @@ void dw_pcie_setup(struct dw_pcie *pci)
 		       PCIE_PL_CHK_REG_CHK_REG_START;
 		dw_pcie_writel_dbi(pci, PCIE_PL_CHK_REG_CONTROL_STATUS, val);
 	}
+
+	if (of_property_read_bool(np, "snps,phy-zrxdc-compliant")) {
+		val = dw_pcie_readl_dbi(pci, PCIE_PORT_GEN3_RELATED);
+		val &= ~PORT_LOGIC_GEN3_ZRXDC_NONCOMPL;
+		dw_pcie_writel_dbi(pci, PCIE_PORT_GEN3_RELATED, val);
+	}
+
 }
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 5a18e94e52c8..427a55ec43c6 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -60,6 +60,9 @@
 #define PCIE_MSI_INTR0_MASK		0x82C
 #define PCIE_MSI_INTR0_STATUS		0x830
 
+#define PCIE_PORT_GEN3_RELATED		0x890
+#define PORT_LOGIC_GEN3_ZRXDC_NONCOMPL		BIT(0)
+
 #define PCIE_ATU_VIEWPORT		0x900
 #define PCIE_ATU_REGION_INBOUND		BIT(31)
 #define PCIE_ATU_REGION_OUTBOUND	0
-- 
2.17.1