linux-kernel - [PATCH] PCI: qcom: Don't deassert reset GPIO during probe

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Message-Id: <20190125232616.25714-1-bjorn.andersson@linaro.org>
Date:   Fri, 25 Jan 2019 15:26:16 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Stanimir Varbanov <svarbanov@...sol.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Khasim Syed Mohammed <khasim.mohammed@...aro.org>,
        Niklas Cassel <niklas.cassel@...aro.org>,
        stable@...r.kernel.org
Subject: [PATCH] PCI: qcom: Don't deassert reset GPIO during probe

Acquiring the reset GPIO low means that reset is being deasserted, this
is followed almost immediately with qcom_pcie_host_init() asserting it,
initializing it and then finally deasserting it again, for the link to
come up.

Some PCIe devices requires a minimum time between the initial deassert
and subsequent reset cycles. In a platform that boots with the reset
GPIO asserted this requirement is being violated by this deassert/assert
pulse.

Acquiring the reset GPIO high will prevent this by matching the state to
the subsequent asserted state.

Cc: stable@...r.kernel.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index d185ea5fe996..a7f703556790 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1228,7 +1228,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 
 	pcie->ops = of_device_get_match_data(dev);
 
-	pcie->reset = devm_gpiod_get_optional(dev, "perst", GPIOD_OUT_LOW);
+	pcie->reset = devm_gpiod_get_optional(dev, "perst", GPIOD_OUT_HIGH);
 	if (IS_ERR(pcie->reset)) {
 		ret = PTR_ERR(pcie->reset);
 		goto err_pm_runtime_put;
-- 
2.18.0