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From:   Krishna chaitanya chundru <quic_krichai@quicinc.com>
To:     helgaas@kernel.org
Cc:     linux-pci@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org, mka@chromium.org,
        quic_vbadigan@quicinc.com, quic_hemantk@quicinc.com,
        quic_nitegupt@quicinc.com, quic_skananth@quicinc.com,
        quic_ramkri@quicinc.com, manivannan.sadhasivam@linaro.org,
        swboyd@chromium.org, dmitry.baryshkov@linaro.org,
        Krishna chaitanya chundru <quic_krichai@quicinc.com>,
        Stanimir Varbanov <svarbanov@mm-sol.com>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Konrad Dybcio <konrad.dybcio@somainline.org>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        Rob Herring <robh@kernel.org>,
        =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= <kw@linux.com>,
        Bjorn Helgaas <bhelgaas@google.com>
Subject: [PATCH v6 2/5] PCI: qcom: Add retry logic for link to be stable in L1ss
Date:   Fri,  9 Sep 2022 14:14:41 +0530
Message-Id: <1662713084-8106-3-git-send-email-quic_krichai@quicinc.com>
In-Reply-To: <1662713084-8106-1-git-send-email-quic_krichai@quicinc.com>
References: <1662713084-8106-1-git-send-email-quic_krichai@quicinc.com>
Precedence: bulk

Some specific devices are taking time to settle the link in L1ss.
So added a retry logic before returning from the suspend op.

Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 36 +++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 6e04d0d..15c2067 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1809,26 +1809,40 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 static int __maybe_unused qcom_pcie_pm_suspend(struct qcom_pcie *pcie)
 {
 	u32 val;
+	ktime_t timeout, start;
 	struct dw_pcie *pci = pcie->pci;
 	struct device *dev = pci->dev;
 
 	if (!pcie->cfg->supports_system_suspend)
 		return 0;
 
-	/* if the link is not active turn off clocks */
-	if (!dw_pcie_link_up(pci)) {
-		dev_info(dev, "Link is not active\n");
-		goto suspend;
-	}
+	start = ktime_get();
+	/* Wait max 200 ms */
+	timeout = ktime_add_ms(start, 200);
 
-	/* if the link is not in l1ss don't turn off clocks */
-	val = readl(pcie->parf + PCIE20_PARF_PM_STTS);
-	if (!(val & PCIE20_PARF_PM_STTS_LINKST_IN_L1SUB)) {
-		dev_warn(dev, "Link is not in L1ss\n");
-		return 0;
+	while (1) {
+
+		if (!dw_pcie_link_up(pci)) {
+			dev_warn(dev, "Link is not active\n");
+			break;
+		}
+
+		/* if the link is not in l1ss don't turn off clocks */
+		val = readl(pcie->parf + PCIE20_PARF_PM_STTS);
+		if ((val & PCIE20_PARF_PM_STTS_LINKST_IN_L1SUB)) {
+			dev_dbg(dev, "Link enters L1ss after %d  ms\n",
+					ktime_to_ms(ktime_get() - start));
+			break;
+		}
+
+		if (ktime_after(ktime_get(), timeout)) {
+			dev_warn(dev, "Link is not in L1ss\n");
+			return 0;
+		}
+
+		udelay(1000);
 	}
 
-suspend:
 	if (pcie->cfg->ops->suspend)
 		pcie->cfg->ops->suspend(pcie);
 
-- 
2.7.4