[PATCH 1/2] i2c: i801: Force no IRQ for Dell Latitude E7450

[Marius Hoch]

The Dell Latitude E7450 uses IRQ 18 for the accelerometer,
but also claims that the SMBus uses IRQ 18. This will
result in:

i801_smbus 0000:00:1f.3: PCI INT C: failed to register GSI
i801_smbus 0000:00:1f.3: Failed to enable SMBus PCI device (-16)
i801_smbus: probe of 0000:00:1f.3 failed with error -16

Force the SMBus IRQ to IRQ_NOTCONNECTED in this case, so that
we fall back to polling, which also seems to be what the (very
dated) Windows 7 drivers on the Dell Latitude E7450 do.

This was tested on Dell Latitude E7450.

Signed-off-by: Marius Hoch <mail@xxxxxxxxxxxxx>
---
 drivers/i2c/busses/i2c-i801.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index ac5326747c51..5fd2ac585160 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -1624,6 +1624,20 @@ static void i801_setup_hstcfg(struct i801_priv *priv)
 	pci_write_config_byte(priv->pci_dev, SMBHSTCFG, hstcfg);
 }
 
+/**
+ * These DELL devices claim an IRQ for the SMBus (usually 18), but we can't use
+ * it, as its actually for the I2C accelerometer.
+ */
+static const struct dmi_system_id dmi_force_no_irq[] = {
+	{
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E7450"),
+		},
+	},
+	{} /* Terminating entry */
+};
+
 static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
 {
 	int err, i;
@@ -1657,6 +1671,12 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	if (!(priv->features & FEATURE_BLOCK_BUFFER))
 		priv->features &= ~FEATURE_BLOCK_PROC;
 
+	if (dmi_check_system(dmi_force_no_irq)) {
+		/* Force no IRQ for these devices, otherwise pcim_enable_device will fail */
+		dev->irq = IRQ_NOTCONNECTED;
+		dev->irq_managed = 1;
+	}
+
 	err = pcim_enable_device(dev);
 	if (err) {
 		dev_err(&dev->dev, "Failed to enable SMBus PCI device (%d)\n",
-- 
2.40.1