[PATCH v2 2/3] PCI: qcom: Read back PARF_LTSSM register

From: Konrad Dybcio <konrad.dybcio@linaro.org>
To: "Bjorn Andersson" <andersson@kernel.org>,
	"Manivannan Sadhasivam" <manivannan.sadhasivam@linaro.org>,
	"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Rob Herring" <robh@kernel.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Philipp Zabel" <p.zabel@pengutronix.de>
Cc: linux-arm-msm@vger.kernel.org, linux-pci@vger.kernel.org,
	 linux-kernel@vger.kernel.org,
	Johan Hovold <johan+linaro@kernel.org>,
	 Konrad Dybcio <konrad.dybcio@linaro.org>
Subject: [PATCH v2 2/3] PCI: qcom: Read back PARF_LTSSM register
Date: Sat, 10 Feb 2024 18:10:06 +0100	[thread overview]
Message-ID: <20240210-topic-8280_pcie-v2-2-1cef4b606883@linaro.org> (raw)
In-Reply-To: <20240210-topic-8280_pcie-v2-0-1cef4b606883@linaro.org>

To ensure write completion, read the PARF_LTSSM register after setting
the LTSSM enable bit before polling for "link up".

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index cbde9effa352..6a469ed213ce 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -539,6 +539,7 @@ static void qcom_pcie_2_3_2_ltssm_enable(struct qcom_pcie *pcie)
 	val = readl(pcie->parf + PARF_LTSSM);
 	val |= LTSSM_EN;
 	writel(val, pcie->parf + PARF_LTSSM);
+	readl(pcie->parf + PARF_LTSSM);
 }
 
 static int qcom_pcie_get_resources_2_3_2(struct qcom_pcie *pcie)

-- 
2.40.1

