linux-kernel - [RFC PATCH v1] PCI: qcom: Use quirk to override incorrect device class

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Date:   Mon, 11 Mar 2019 15:56:36 +0100
From:   Marc Gonzalez <marc.w.gonzalez@...e.fr>
To:     Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Stanimir Varbanov <stanimir.varbanov@...aro.org>,
        PCI <linux-pci@...r.kernel.org>,
        MSM <linux-arm-msm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jeffrey Hugo <jhugo@...eaurora.org>
Subject: [RFC PATCH v1] PCI: qcom: Use quirk to override incorrect device
 class

Some chips report an incorrect device class. Override the incorrect
value using a quirk, instead of code in the read function.

Signed-off-by: Marc Gonzalez <marc.w.gonzalez@...e.fr>
---
FWIW, this quirk is no longer required on recent chips:
msm8996 (tested by Stanimir), msm8998 (tested by me), sdm845 (untested) are unaffected
apq/ipq8064 is affected => what is the device ID for these chips?
others?

Stanimir added: "this will become a real problem (now we use the driver as RC)
when someone decide to use it as an endpoint"
---
 drivers/pci/controller/dwc/pcie-qcom.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 3de5510fd3d5..94da2c9c2ad5 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1136,17 +1136,15 @@ static int qcom_pcie_rd_own_conf(struct pcie_port *pp, int where, int size,
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
 
-	/* the device class is not reported correctly from the register */
-	if (where == PCI_CLASS_REVISION && size == 4) {
-		*val = readl(pci->dbi_base + PCI_CLASS_REVISION);
-		*val &= 0xff;	/* keep revision id */
-		*val |= PCI_CLASS_BRIDGE_PCI << 16;
-		return PCIBIOS_SUCCESSFUL;
-	}
-
 	return dw_pcie_read(pci->dbi_base + where, size, val);
 }
 
+static void qcom_fixup_class(struct pci_dev *dev)
+{
+	dev->class = PCI_CLASS_BRIDGE_PCI << 8;
+}
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_QCOM, PCI_ANY_ID, qcom_fixup_class);
+
 static const struct dw_pcie_host_ops qcom_pcie_dw_ops = {
 	.host_init = qcom_pcie_host_init,
 	.rd_own_conf = qcom_pcie_rd_own_conf,
-- 
2.17.1