[PATCH v10 1/8] mfd: intel-lpss: add resource conflict quirk for Dell Latitude 5285

[Thierry Chatard <tchatard@gmail.com>]

The Dell Latitude 5285 2-in-1 has a BIOS bug where the ACPI GEXP device
and the I2C4 controller (INT3446) both claim the same MMIO region via the
shared SB04 variable. This causes intel_lpss_acpi to fail binding to I2C4
with -EBUSY, preventing the front camera (OV5670) sensor from being
registered.

Match the affected machine by DMI and the affected device by ACPI ID,
carrying QUIRK_IGNORE_RESOURCE_CONFLICTS in the ACPI match data and
applying it to the per-device info in probe. This follows the quirk
organisation used by the PCI counterpart.

Assisted-by: Claude Code:claude-opus-4-8
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Thierry Chatard <tchatard@gmail.com>
---
 drivers/mfd/intel-lpss-acpi.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/mfd/intel-lpss-acpi.c b/drivers/mfd/intel-lpss-acpi.c
index d4b24a717..9d7d0ad62 100644
--- a/drivers/mfd/intel-lpss-acpi.c
+++ b/drivers/mfd/intel-lpss-acpi.c
@@ -8,7 +8,9 @@
  *          Mika Westerberg <mika.westerberg@linux.intel.com>
  */
 
+#include <linux/acpi.h>
 #include <linux/device.h>
+#include <linux/dmi.h>
 #include <linux/gfp_types.h>
 #include <linux/ioport.h>
 #include <linux/module.h>
@@ -171,6 +173,27 @@ static const struct acpi_device_id intel_lpss_acpi_ids[] = {
 };
 MODULE_DEVICE_TABLE(acpi, intel_lpss_acpi_ids);
 
+/*
+ * Devices that need a quirk applied only on the machines matched by
+ * intel_lpss_quirk_dmi[] below. The quirk to apply is carried in the
+ * matching entry's driver_data.
+ */
+static const struct acpi_device_id intel_lpss_acpi_quirk_ids[] = {
+	/* Dell Latitude 5285: ACPI GEXP device conflicts with I2C4 (INT3446) */
+	{ "INT3446", QUIRK_IGNORE_RESOURCE_CONFLICTS },
+	{ }
+};
+
+static const struct dmi_system_id intel_lpss_quirk_dmi[] = {
+	{
+		.matches = {
+			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "Latitude 5285"),
+		},
+	},
+	{ }
+};
+
 static int intel_lpss_acpi_probe(struct platform_device *pdev)
 {
 	const struct intel_lpss_platform_info *data;
@@ -185,6 +208,15 @@ static int intel_lpss_acpi_probe(struct platform_device *pdev)
 	if (!info)
 		return -ENOMEM;
 
+	/* Apply per-device quirks that are only needed on certain machines */
+	if (dmi_check_system(intel_lpss_quirk_dmi)) {
+		const struct acpi_device_id *id;
+
+		id = acpi_match_device(intel_lpss_acpi_quirk_ids, &pdev->dev);
+		if (id)
+			info->quirks |= id->driver_data;
+	}
+
 	/* No need to check mem and irq here as intel_lpss_probe() does it for us */
 	info->mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	info->irq = platform_get_irq(pdev, 0);
-- 
2.53.0