[PATCH 04/13] platform/apple-gmux: Fix Interrupts for MMIO systems
From: Atharva Tiwari
Date: Sun Oct 25 2026 - 00:03:11 EST
on MMIO systems, we need check to for failure in interrupts,
and we have implimented display hotplug to wake up the gpu.
Co-developed-by: Andre Eikmeyer <dev@deq.rocks>
Signed-off-by: Andre Eikmeyer <dev@deq.rocks>
Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@xxxxxxxxx>
---
drivers/platform/x86/apple-gmux.c | 96 +++++++++++++++++++++++++++----
1 file changed, 84 insertions(+), 12 deletions(-)
diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index 076ed7ba6..bef87a57a 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -6,6 +6,8 @@
* Copyright (C) 2010-2012 Andreas Heider <andreas@xxxxxxxx>
* Copyright (C) 2015 Lukas Wunner <lukas@xxxxxxxxx>
* Copyright (C) 2023 Orlando Chamberlain <orlandoch.dev@xxxxxxxxx>
+ * Copyright (C) 2026 Atharva Tiwari <atharvatiwarilinuxdev@xxxxxxxxx>
+ * Copyright (C) 2026 Andre Eikmeyer <dev@deq.rocks>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -23,6 +25,8 @@
#include <linux/vga_switcheroo.h>
#include <linux/debugfs.h>
#include <linux/dmi.h>
+#include <linux/workqueue.h>
+#include <linux/pm_runtime.h>
#include <acpi/video.h>
#include <asm/io.h>
@@ -66,6 +70,10 @@ struct apple_gmux_data {
struct backlight_device *bdev;
+ /* interrupt handling data */
+ bool external_state;
+ struct work_struct interrupt_work;
+
/* power handling data */
struct pci_dev *discrete_pdev;
bool uses_pwrd;
@@ -105,6 +113,7 @@ struct apple_gmux_config {
#define GMUX_INTERRUPT_STATUS_ACTIVE 0
#define GMUX_INTERRUPT_STATUS_DISPLAY (1 << 0)
+#define GMUX_INTERRUPT_STATUS_FAILED (1 << 1)
#define GMUX_INTERRUPT_STATUS_POWER (1 << 2)
#define GMUX_INTERRUPT_STATUS_HOTPLUG (1 << 3)
@@ -417,8 +426,8 @@ static const struct backlight_ops gmux_bl_ops = {
* the discrete GPU can then be woken to drive the newly connected display.
* The ability to switch AUX on these generations could be used to improve
* reliability of hotplug detection by having the integrated GPU poll the
- * ports while the discrete GPU is asleep, but currently we do not make use
- * of this feature.
+ * ports while the discrete GPU is asleep, but currently we only make use of
+ * this feature on MMIO/T2 Macs.
*
* Our switching policy for the external port is that on those generations
* which are able to switch it fully, the port is switched together with the
@@ -796,9 +805,10 @@ static const struct apple_gmux_config apple_gmux_mmio = {
* value is read and then inverted.
*
* Because Linux masquerades as Darwin, it ends up in the notification-only code
- * path. On MMIO gmux's, this seems to lead to us being unable to clear interrupts,
- * unless we call GMSP(0). Without this, there is a flood of status=0 interrupts
- * that can't be cleared. This issue seems to be unique to MMIO gmux's.
+ * path. On MMIO gmux's, The Polarity is initally left in a undefined state leading
+ * to lots of interrupts, that we can't clear, to fix this we set the polarity to 0
+ * everytime we enable interrupts, On MMIO gmux's, GMLV reads the same GPIO pin as
+ * GMSP, and setting the polarity to 1, stops the Interrupts completely.
*/
static inline void gmux_disable_interrupts(struct apple_gmux_data *gmux_data)
@@ -807,8 +817,11 @@ static inline void gmux_disable_interrupts(struct apple_gmux_data *gmux_data)
GMUX_INTERRUPT_DISABLE);
}
-static inline void gmux_enable_interrupts(struct apple_gmux_data *gmux_data)
+static inline void gmux_enable_interrupts(struct apple_gmux_data *gmux_data, bool do_gmsp)
{
+ if (gmux_data->type == APPLE_GMUX_TYPE_MMIO && do_gmsp)
+ acpi_execute_simple_method(gmux_data->dhandle, "GMSP", 0);
+
gmux_write8(gmux_data, GMUX_PORT_INTERRUPT_ENABLE,
GMUX_INTERRUPT_ENABLE);
}
@@ -825,23 +838,78 @@ static void gmux_clear_interrupts(struct apple_gmux_data *gmux_data)
/* to clear interrupts write back current status */
status = gmux_interrupt_get_status(gmux_data);
gmux_write8(gmux_data, GMUX_PORT_INTERRUPT_STATUS, status);
- /* Prevent flood of status=0 interrupts */
- if (gmux_data->config == &apple_gmux_mmio)
- acpi_execute_simple_method(gmux_data->dhandle, "GMSP", 0);
}
+static void gmux_notify_work(struct work_struct *work)
+{
+ struct apple_gmux_data *gmux_data =
+ container_of(work, struct apple_gmux_data, interrupt_work);
+ u8 status;
+ bool turn_on_gpu = false;
+
+ status = gmux_interrupt_get_status(gmux_data);
+ if (!status)
+ return;
+
+ gmux_disable_interrupts(gmux_data);
+ pr_debug("Notify handler called: status %d\n", status);
+ acpi_execute_simple_method(gmux_data->dhandle, "GMSP", 0);
+
+ status = gmux_interrupt_get_status(gmux_data);
+ while (status) {
+ gmux_write8(gmux_data, GMUX_PORT_INTERRUPT_STATUS, status);
+ if (status & GMUX_INTERRUPT_STATUS_FAILED) {
+ pr_warn_ratelimited("interrupt failed: status: 0x%x\n", status);
+ status = gmux_interrupt_get_status(gmux_data);
+ continue;
+ }
+ if (status & GMUX_INTERRUPT_STATUS_POWER)
+ complete(&gmux_data->powerchange_done);
+
+ if (status & GMUX_INTERRUPT_STATUS_HOTPLUG) {
+ /*
+ * We get an interrupt every time a display connects or disconnects, but
+ * the GET_DISPLAY port only tells us if a display is connected or not,
+ * so we resume every time a display is connected or disconnected.
+ */
+ bool external_state = !!gmux_read8(gmux_data,
+ GMUX_PORT_SWITCH_GET_DISPLAY);
+ if (external_state != gmux_data->external_state) {
+ gmux_data->external_state = external_state;
+ if (external_state)
+ pr_debug("A display has been connected\n");
+ else
+ pr_debug("All displays has been disconnected\n");
+ }
+ if (!gmux_data->external_switchable && gmux_data->discrete_pdev)
+ turn_on_gpu = true;
+ }
+ status = gmux_interrupt_get_status(gmux_data);
+ }
+
+ gmux_enable_interrupts(gmux_data, 0);
+
+ if (turn_on_gpu)
+ pm_runtime_resume(&gmux_data->discrete_pdev->dev);
+
+}
static void gmux_notify_handler(acpi_handle device, u32 value, void *context)
{
u8 status;
struct pnp_dev *pnp = (struct pnp_dev *)context;
struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
+ if (gmux_data->type == APPLE_GMUX_TYPE_MMIO) {
+ schedule_work(&gmux_data->interrupt_work);
+ return;
+ }
+
status = gmux_interrupt_get_status(gmux_data);
gmux_disable_interrupts(gmux_data);
pr_debug("Notify handler called: status %d\n", status);
gmux_clear_interrupts(gmux_data);
- gmux_enable_interrupts(gmux_data);
+ gmux_enable_interrupts(gmux_data, 0);
if (status & GMUX_INTERRUPT_STATUS_POWER)
complete(&gmux_data->powerchange_done);
@@ -935,7 +1003,7 @@ static int gmux_resume(struct device *dev)
struct pnp_dev *pnp = to_pnp_dev(dev);
struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
- gmux_enable_interrupts(gmux_data);
+ gmux_enable_interrupts(gmux_data, 1);
gmux_write_switch_state(gmux_data);
if (gmux_data->power_state == VGA_SWITCHEROO_OFF)
gmux_set_discrete_state(gmux_data, gmux_data->power_state);
@@ -996,6 +1064,7 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
pr_err("couldn't remap gmux mmio region");
goto err_release;
}
+ INIT_WORK(&gmux_data->interrupt_work, gmux_notify_work);
goto get_version;
case APPLE_GMUX_TYPE_INDEXED:
gmux_data->config = &apple_gmux_index;
@@ -1115,7 +1184,7 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
apple_gmux_data = gmux_data;
init_completion(&gmux_data->powerchange_done);
- gmux_enable_interrupts(gmux_data);
+ gmux_enable_interrupts(gmux_data, 1);
gmux_read_switch_state(gmux_data);
/*
@@ -1150,6 +1219,8 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
err_unmap:
if (gmux_data->iomem_base)
iounmap(gmux_data->iomem_base);
+ if (gmux_data->type == APPLE_GMUX_TYPE_MMIO)
+ cancel_work_sync(&gmux_data->interrupt_work);
err_release:
if (gmux_data->config->resource_type == IORESOURCE_MEM)
release_mem_region(gmux_data->iostart, gmux_data->iolen);
@@ -1168,6 +1239,7 @@ static void gmux_remove(struct pnp_dev *pnp)
vga_switcheroo_unregister_handler();
pci_dev_put(gmux_data->discrete_pdev);
gmux_disable_interrupts(gmux_data);
+ cancel_work_sync(&gmux_data->interrupt_work);
if (gmux_data->gpe >= 0) {
acpi_disable_gpe(NULL, gmux_data->gpe);
acpi_remove_notify_handler(gmux_data->dhandle,
--
2.55.0