On Wed, 12 Aug 2026, Andre Eikmeyer wrote: > From: Atharva Tiwari <[email protected]> > > The discrete GPU on the MacBookPro15,1 does not return after the legacy
"return" seems wrong term in this sentence. > GMUX power-on sequence. PCI configuration space remains inaccessible, so > runtime PM cannot provide usable hybrid graphics with the integrated GPU > as primary. > > Evaluate the firmware PWG1 and PWG3 link methods around the GMUX > transition and wait for PCI configuration space before completing power-on. > Keep the sequence limited to the MacBookPro15,1 and retain the existing > path for every other model. > This was tested on both the 2018 and 2019 MacBookPro15,1 revisions with the > integrated GPU as primary. The discrete GPU transitions between DynOff and > DynPwr, and external displays work across the transitions. > > Co-developed-by: Andre Eikmeyer <[email protected]> > Signed-off-by: Andre Eikmeyer <[email protected]> > Signed-off-by: Atharva Tiwari <[email protected]> > --- > drivers/platform/x86/apple-gmux.c | 86 ++++++++++++++++++++++++++++--- > 1 file changed, 80 insertions(+), 6 deletions(-) > > diff --git a/drivers/platform/x86/apple-gmux.c > b/drivers/platform/x86/apple-gmux.c > index 9c728ac..ccb059a 100644 > --- a/drivers/platform/x86/apple-gmux.c > +++ b/drivers/platform/x86/apple-gmux.c > @@ -22,6 +22,7 @@ > #include <linux/pci.h> > #include <linux/vga_switcheroo.h> > #include <linux/debugfs.h> > +#include <linux/dmi.h> > #include <acpi/video.h> > #include <asm/io.h> > > @@ -74,6 +75,8 @@ struct apple_gmux_data { > enum vga_switcheroo_client_id switch_state_external; > enum vga_switcheroo_state power_state; > struct completion powerchange_done; > + struct pci_dev *discrete_pdev; > + bool use_pwg_power_sequence; > > /* debugfs data */ > u8 selected_port; > @@ -82,6 +85,34 @@ struct apple_gmux_data { > > static struct apple_gmux_data *apple_gmux_data; > > +static int gmux_call_pwg(struct apple_gmux_data *gmux_data, > + const char *method) > +{ > + acpi_handle handle = ACPI_HANDLE(&gmux_data->discrete_pdev->dev); > + unsigned long long result; > + acpi_status status; > + > + if (!handle) > + return -ENODEV; > + > + status = acpi_evaluate_integer(handle, (acpi_string)method, NULL, > + &result); > + if (ACPI_FAILURE(status)) { > + dev_err(&gmux_data->discrete_pdev->dev, > + "failed to evaluate %s: %s\n", method, > + acpi_format_exception(status)); Add hinclude for dev_err(). > + return -EIO; > + } > + > + if (result) { > + dev_err(&gmux_data->discrete_pdev->dev, > + "%s failed: %llu\n", method, result); > + return -EIO; > + } > + > + return 0; > +} > + > struct apple_gmux_config { > u8 (*read8)(struct apple_gmux_data *gmux_data, int port); > void (*write8)(struct apple_gmux_data *gmux_data, int port, u8 val); > @@ -510,14 +541,49 @@ static int gmux_switch_ddc(enum > vga_switcheroo_client_id id) > static int gmux_set_discrete_state(struct apple_gmux_data *gmux_data, > enum vga_switcheroo_state state) > { > + int ret; > + > reinit_completion(&gmux_data->powerchange_done); > > if (state == VGA_SWITCHEROO_ON) { > - gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 1); > - gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 3); > + if (gmux_data->use_pwg_power_sequence && > + gmux_data->discrete_pdev) { > + u16 vendor; > + int i; > + > + gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 2); > + msleep(100); > + gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 3); > + > + ret = gmux_call_pwg(gmux_data, "PWG1"); > + if (ret) > + return ret; > + > + for (i = 0; i < 1000; i++) { > + pci_read_config_word(gmux_data->discrete_pdev, > + PCI_VENDOR_ID, &vendor); > + if (vendor != 0xffff) > + break; > + usleep_range(1000, 2000); > + } > + if (vendor == 0xffff) { Does this duplicate pci_bus_read_dev_vendor_id() ? > + dev_err(&gmux_data->discrete_pdev->dev, > + "timed out waiting for PCI config > space\n"); > + return -ETIMEDOUT; > + } > + > + ret = gmux_call_pwg(gmux_data, "PWG3"); > + if (ret) > + return ret; > + } else { > + gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 1); > + gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 3); > + } > pr_debug("Discrete card powered up\n"); > } else { > gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 1); > + if (gmux_data->use_pwg_power_sequence) > + usleep_range(10000, 11000); Where do these numbers come from? > gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 0); > pr_debug("Discrete card powered down\n"); > } > @@ -549,11 +615,16 @@ static enum vga_switcheroo_client_id > gmux_get_client_id(struct pci_dev *pdev) > */ > if (pdev->vendor == PCI_VENDOR_ID_INTEL) > return VGA_SWITCHEROO_IGD; > - else if (pdev->vendor == PCI_VENDOR_ID_NVIDIA && > - pdev->device == 0x0863) > + if (pdev->vendor == PCI_VENDOR_ID_NVIDIA && pdev->device == 0x0863) > return VGA_SWITCHEROO_IGD; > - else > - return VGA_SWITCHEROO_DIS; > + > + if (apple_gmux_data->use_pwg_power_sequence && > + apple_gmux_data->discrete_pdev != pdev) { > + pci_dev_put(apple_gmux_data->discrete_pdev); > + apple_gmux_data->discrete_pdev = pci_dev_get(pdev); > + } > + > + return VGA_SWITCHEROO_DIS; > } > > static const struct vga_switcheroo_handler gmux_handler_no_ddc = { > @@ -803,6 +874,8 @@ static int gmux_probe(struct pnp_dev *pnp, const struct > pnp_device_id *id) > if (!gmux_data) > return -ENOMEM; > pnp_set_drvdata(pnp, gmux_data); > + gmux_data->use_pwg_power_sequence = type == APPLE_GMUX_TYPE_MMIO && > + dmi_match(DMI_PRODUCT_NAME, "MacBookPro15,1"); This formatting is hard to read. > switch (type) { > case APPLE_GMUX_TYPE_MMIO: > @@ -1009,6 +1082,7 @@ static void gmux_remove(struct pnp_dev *pnp) > } else > release_region(gmux_data->iostart, gmux_data->iolen); > apple_gmux_data = NULL; > + pci_dev_put(gmux_data->discrete_pdev); > kfree(gmux_data); > } > > -- i.
