Messages in this thread | | | Date | Thu, 2 Dec 2021 22:43:36 +0200 | From | Laurent Pinchart <> | Subject | Re: [PATCH] mfd: intel-lpss: Fix I2C4 not being available on the Microsoft Surface Go & Go 2 |
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Hi Hans,
Thank you for the patch.
On Thu, Dec 02, 2021 at 09:13:51PM +0100, Hans de Goede wrote: > Many DSDTs for Kaby Lake and Kaby Lake Refresh models contain a > _SB.PCI0.GEXP ACPI Device node describing an I2C attached 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
s/this/that/ (or ". 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 a 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.
This will make the life of the Go and Go2 users *much* easier.
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > Cc: Dan Scally <djrscally@gmail.com> > Cc: Kate Hsuan <hpa@redhat.com> > Cc: Maximilian Luz <luzmaximilian@gmail.com> > Signed-off-by: Hans de Goede <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 a872b4485eac..593290ff08a6 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(0x8086, 0x9d64, 0x152d, 0x1182), }, > + /* Microsoft Surface Go 2 I2C4 */ > + { PCI_DEVICE_SUB(0x8086, 0x9d64, 0x152d, 0x1237), }, > + { }
Reading the commit message, I was going to mention that the match should probably be machine-dependent, but that seems to be covered by the PCI subsystem ID.
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> +}; > + > 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;
-- Regards,
Laurent Pinchart
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