linux-kernel - [PATCH AUTOSEL 4.19 082/167] PCI: qcom: Don't deassert reset GPIO during probe

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Message-Id: <20190903162519.7136-82-sashal@kernel.org>
Date:   Tue,  3 Sep 2019 12:23:54 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Stanimir Varbanov <svarbanov@...sol.com>,
        Sasha Levin <sashal@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-pci@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 082/167] PCI: qcom: Don't deassert reset GPIO during probe

From: Bjorn Andersson <bjorn.andersson@...aro.org>

[ Upstream commit 02b485e31d98265189b91f3e69c43df2ed50610c ]

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.

Acquire the reset GPIO high to prevent this situation by matching the
state to the subsequent asserted state.

Fixes: 82a823833f4e ("PCI: qcom: Add Qualcomm PCIe controller driver")
Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
[lorenzo.pieralisi@....com: updated commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Acked-by: Stanimir Varbanov <svarbanov@...sol.com>
Cc: stable@...r.kernel.org
Signed-off-by: Sasha Levin <sashal@...nel.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 79f06c76ae071..e292801fff7fd 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1230,7 +1230,7 @@ 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;
-- 
2.20.1