From e6b142060b24014bfcf86ae5b1facc5e99e84176 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Fri, 3 Dec 2021 12:51:08 +0100 Subject: [PATCH] mfd: intel-lpss: Fix I2C4 not being available on the Microsoft Surface Go & Go 2 Many DSDTs for Kaby Lake and Kaby Lake Refresh models contain a _SB.PCI0.GEXP ACPI Device node describing an I2C attached PCA953x GPIO expander. This seems to be something which is copy and pasted from the DSDT from some reference design since this ACPI Device is present even on models where no such GPIO expander is used at all, such as on the Microsoft Surface Go & Go 2. This ACPI Device is a problem because it contains a SystemMemory OperationRegion which covers the MMIO for the I2C4 I2C controller. This causes the MFD cell for the I2C4 controller to not be instantiated due to a resource conflict, requiring the use of acpi_enforce_resources=lax to work around this. I have done an extensive analysis of all the ACPI tables on the Microsoft Surface Go and the _SB.PCI0.GEXP ACPI Device's methods are not used by any code in the ACPI tables, neither are any of them directly called by any Linux kernel code. This is unsurprising since running i2cdetect on the I2C4 bus shows that there is no GPIO expander chip present on these devices at all. This commit adds a PCI subsystem vendor:device table listing PCI devices where it is known to be safe to ignore resource conflicts with ACPI declared SystemMemory regions. This makes the I2C4 bus work out of the box on the Microsoft Surface Go & Go 2, which is necessary for the cameras on these devices to work. Signed-off-by: Hans de Goede Reviewed-by: Laurent Pinchart Reviewed-by: Andy Shevchenko Acked-by: Mika Westerberg Signed-off-by: Lee Jones Link: https://lore.kernel.org/r/20211203115108.89661-1-hdegoede@redhat.com --- drivers/mfd/intel-lpss-pci.c | 12 ++++++++++++ drivers/mfd/intel-lpss.c | 1 + drivers/mfd/intel-lpss.h | 1 + 3 files changed, 14 insertions(+) diff --git a/drivers/mfd/intel-lpss-pci.c b/drivers/mfd/intel-lpss-pci.c index a59aa147959b..5513fae6be92 100644 --- a/drivers/mfd/intel-lpss-pci.c +++ b/drivers/mfd/intel-lpss-pci.c @@ -17,6 +17,15 @@ #include "intel-lpss.h" +/* Some DSDTs have an unused GEXP ACPI device conflicting with I2C4 resources */ +static const struct pci_device_id ignore_resource_conflicts_ids[] = { + /* Microsoft Surface Go (version 1) I2C4 */ + { PCI_DEVICE_SUB(PCI_VENDOR_ID_INTEL, 0x9d64, 0x152d, 0x1182), }, + /* Microsoft Surface Go 2 I2C4 */ + { PCI_DEVICE_SUB(PCI_VENDOR_ID_INTEL, 0x9d64, 0x152d, 0x1237), }, + { } +}; + static int intel_lpss_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) { @@ -35,6 +44,9 @@ static int intel_lpss_pci_probe(struct pci_dev *pdev, info->mem = &pdev->resource[0]; info->irq = pdev->irq; + if (pci_match_id(ignore_resource_conflicts_ids, pdev)) + info->ignore_resource_conflicts = true; + pdev->d3cold_delay = 0; /* Probably it is enough to set this for iDMA capable devices only */ diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c index 0e15afc39f54..cfbee2cfba6b 100644 --- a/drivers/mfd/intel-lpss.c +++ b/drivers/mfd/intel-lpss.c @@ -401,6 +401,7 @@ int intel_lpss_probe(struct device *dev, return ret; lpss->cell->swnode = info->swnode; + lpss->cell->ignore_resource_conflicts = info->ignore_resource_conflicts; intel_lpss_init_dev(lpss); diff --git a/drivers/mfd/intel-lpss.h b/drivers/mfd/intel-lpss.h index 22dbc4aed793..062ce95b68b9 100644 --- a/drivers/mfd/intel-lpss.h +++ b/drivers/mfd/intel-lpss.h @@ -19,6 +19,7 @@ struct software_node; struct intel_lpss_platform_info { struct resource *mem; + bool ignore_resource_conflicts; int irq; unsigned long clk_rate; const char *clk_con_id;