linux-kernel - [PATCH v3] PCI: qcom: Allow L1 and its sub states

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Date:   Fri, 15 Jul 2022 17:29:25 +0530
From:   Krishna chaitanya chundru <quic_krichai@...cinc.com>
To:     helgaas@...nel.org
Cc:     linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, mka@...omium.org,
        quic_vbadigan@...cinc.com, quic_hemantk@...cinc.com,
        quic_nitegupt@...cinc.com, quic_skananth@...cinc.com,
        quic_ramkri@...cinc.com, manivannan.sadhasivam@...aro.org,
        swboyd@...omium.org, dmitry.baryshkov@...aro.org,
        Krishna chaitanya chundru <quic_krichai@...cinc.com>,
        Stanimir Varbanov <svarbanov@...sol.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH v3] PCI: qcom: Allow L1 and its sub states

Allow L1 and its sub-states in the qcom pcie driver.
By default this is disabled in the qcom specific hardware.
So enabling it explicitly only for controllers belonging to
2_7_0.

This patch will not affect any link capability registers, this
will allow the link transitions to L1 and its sub states only
if they are already supported.

Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
----

Changes since v1 & v2:
	- Update in the commit text only.
---
 drivers/pci/controller/dwc/pcie-qcom.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index a7202f0..5ef444f 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -41,6 +41,9 @@
 #define L23_CLK_RMV_DIS				BIT(2)
 #define L1_CLK_RMV_DIS				BIT(1)
 
+#define PCIE20_PARF_PM_CTRL			0x20
+#define REQ_NOT_ENTR_L1				BIT(5)
+
 #define PCIE20_PARF_PHY_CTRL			0x40
 #define PHY_CTRL_PHY_TX0_TERM_OFFSET_MASK	GENMASK(20, 16)
 #define PHY_CTRL_PHY_TX0_TERM_OFFSET(x)		((x) << 16)
@@ -1261,6 +1264,11 @@ static int qcom_pcie_init_2_7_0(struct qcom_pcie *pcie)
 	val |= BIT(4);
 	writel(val, pcie->parf + PCIE20_PARF_MHI_CLOCK_RESET_CTRL);
 
+	/* Enable L1 and L1ss */
+	val = readl(pcie->parf + PCIE20_PARF_PM_CTRL);
+	val &= ~REQ_NOT_ENTR_L1;
+	writel(val, pcie->parf + PCIE20_PARF_PM_CTRL);
+
 	if (IS_ENABLED(CONFIG_PCI_MSI)) {
 		val = readl(pcie->parf + PCIE20_PARF_AXI_MSTR_WR_ADDR_HALT);
 		val |= BIT(31);
-- 
2.7.4