Date:	Tue, 10 Jul 2012 17:05:55 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Arun Raghavan <arun.raghavan@...labora.co.uk>
Cc:	Seth Forshee <seth.forshee@...onical.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] apple-gmux: Restore switch registers on suspend/resume

On Tue, Jul 10, 2012 at 09:09:53AM +0530, Arun Raghavan wrote:
> After suspend and resume, the values of these registers seem to change
> from what they were at suspend time, potentially preventing the actual
> output lines from being enabled post-resume. This saves relevant state
> at suspend and restores it when resumed.
> 
> This is at least required on the MacBook Pro 8.2 when the Intel GPU is
> manually selected in GRUB config before the kernel is loaded.

I'd really rather add proper switcheroo support. Andreas, I have a patch 
with your name on it that appears to work (attached) - any objections to 
getting this merged?

commit 225a5a4ba90e9cf3de836c936cd01e9828cd0765
Author: Matthew Garrett <mjg@...hat.com>
Date:   Thu Mar 22 09:28:27 2012 -0400

    gmux switcheroo

diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index 694a15a..ef2c9ac 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -2,6 +2,7 @@
  *  Gmux driver for Apple laptops
  *
  *  Copyright (C) Canonical Ltd. <seth.forshee@...onical.com>
+ *  Copyright (C) 2010-2012 Andreas Heider <andreas@...tr.de>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2 as
@@ -20,13 +21,22 @@
 #include <linux/slab.h>
 #include <acpi/video.h>
 #include <asm/io.h>
+#include <linux/pci.h>
+#include <linux/vga_switcheroo.h>
+#include <linux/delay.h>
 
-struct apple_gmux_data {
+static struct apple_gmux_data {
 	unsigned long iostart;
 	unsigned long iolen;
+	acpi_handle dhandle;
+	enum vga_switcheroo_client_id resume_client_id;
 
 	struct backlight_device *bdev;
-};
+} gmux_data;
+
+static struct pci_dev *discrete;
+
+DECLARE_COMPLETION(powerchange_done);
 
 /*
  * gmux port offsets. Many of these are not yet used, but may be in the
@@ -59,32 +69,29 @@ struct apple_gmux_data {
 #define GMUX_BRIGHTNESS_MASK		0x00ffffff
 #define GMUX_MAX_BRIGHTNESS		GMUX_BRIGHTNESS_MASK
 
-static inline u8 gmux_read8(struct apple_gmux_data *gmux_data, int port)
+static inline u8 gmux_read8(int port)
 {
-	return inb(gmux_data->iostart + port);
+	return inb(gmux_data.iostart + port);
 }
 
-static inline void gmux_write8(struct apple_gmux_data *gmux_data, int port,
-			       u8 val)
+static inline void gmux_write8(int port, u8 val)
 {
-	outb(val, gmux_data->iostart + port);
+	outb(val, gmux_data.iostart + port);
 }
 
-static inline u32 gmux_read32(struct apple_gmux_data *gmux_data, int port)
+static inline u32 gmux_read32(int port)
 {
-	return inl(gmux_data->iostart + port);
+	return inl(gmux_data.iostart + port);
 }
 
 static int gmux_get_brightness(struct backlight_device *bd)
 {
-	struct apple_gmux_data *gmux_data = bl_get_data(bd);
-	return gmux_read32(gmux_data, GMUX_PORT_BRIGHTNESS) &
+	return gmux_read32(GMUX_PORT_BRIGHTNESS) &
 	       GMUX_BRIGHTNESS_MASK;
 }
 
 static int gmux_update_status(struct backlight_device *bd)
 {
-	struct apple_gmux_data *gmux_data = bl_get_data(bd);
 	u32 brightness = bd->props.brightness;
 
 	if (bd->props.state & BL_CORE_SUSPENDED)
@@ -96,54 +103,225 @@ static int gmux_update_status(struct backlight_device *bd)
 	 * accept a single u32 write, but the old method also works, so we
 	 * just use the old method for all gmux versions.
 	 */
-	gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS, brightness);
-	gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 1, brightness >> 8);
-	gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 2, brightness >> 16);
-	gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 3, 0);
+	gmux_write8(GMUX_PORT_BRIGHTNESS, brightness);
+	gmux_write8(GMUX_PORT_BRIGHTNESS + 1, brightness >> 8);
+	gmux_write8(GMUX_PORT_BRIGHTNESS + 2, brightness >> 16);
+	gmux_write8(GMUX_PORT_BRIGHTNESS + 3, 0);
+
+	return 0;
+}
+
+static int gmux_switchto(enum vga_switcheroo_client_id id)
+{
+	if (id == VGA_SWITCHEROO_IGD) {
+		gmux_write8(GMUX_PORT_SWITCH_DDC, 1);
+		gmux_write8(GMUX_PORT_SWITCH_DISPLAY, 2);
+		gmux_write8(GMUX_PORT_SWITCH_EXTERNAL, 2);
+	} else {
+		gmux_write8(GMUX_PORT_SWITCH_DDC, 2);
+		gmux_write8(GMUX_PORT_SWITCH_DISPLAY, 3);
+		gmux_write8(GMUX_PORT_SWITCH_EXTERNAL, 3);
+	}
+
+	return 0;
+}
+
+static int gmux_call_acpi_pwrd(int arg)
+{
+	acpi_handle gfx_handle = DEVICE_ACPI_HANDLE(&discrete->dev);
+	acpi_handle pwrd_handle = NULL;
+	acpi_status status = AE_OK;
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object arg0 = { ACPI_TYPE_INTEGER };
+	struct acpi_object_list arg_list = { 1, &arg0 };
+
+	if (!gfx_handle) {
+		pr_err("Cannot find device ACPI handle\n");
+		return -ENODEV;
+	}
+
+	status = acpi_get_handle(gfx_handle, "PWRD", &pwrd_handle);
+	if (ACPI_FAILURE(status)) {
+		pr_err("Cannot get PWRD handle: %s\n",
+		       acpi_format_exception(status));
+		return -ENODEV;
+	}
 
+	arg0.integer.value = arg;
+
+	status = acpi_evaluate_object(pwrd_handle, NULL, &arg_list, &buffer);
+	if (ACPI_FAILURE(status)) {
+		pr_err("PWRD call failed: %s\n",
+		       acpi_format_exception(status));
+		return -ENODEV;
+	}
+
+	kfree(buffer.pointer);
 	return 0;
 }
 
+static int gmux_set_discrete_state(enum vga_switcheroo_state state)
+{
+	/* TODO: locking for completions needed? */
+	init_completion(&powerchange_done);
+
+	if (state == VGA_SWITCHEROO_ON) {
+		gmux_call_acpi_pwrd(0);
+		gmux_write8(GMUX_PORT_DISCRETE_POWER, 1);
+		gmux_write8(GMUX_PORT_DISCRETE_POWER, 3);
+	} else {
+		gmux_write8(GMUX_PORT_DISCRETE_POWER, 1);
+		gmux_write8(GMUX_PORT_DISCRETE_POWER, 0);
+		gmux_call_acpi_pwrd(1);
+	}
+
+	if (wait_for_completion_interruptible_timeout(&powerchange_done,
+						      msecs_to_jiffies(200)))
+		pr_info("completion timeout\n");
+
+	return 0;
+}
+
+static int gmux_set_power_state(enum vga_switcheroo_client_id id,
+				enum vga_switcheroo_state state)
+{
+	if (id == VGA_SWITCHEROO_IGD)
+		return 0;
+
+	return gmux_set_discrete_state(state);
+}
+
+static int gmux_init(void)
+{
+	return 0;
+}
+
+static int gmux_get_client_id(struct pci_dev *pdev)
+{
+	/* early mbps with switchable graphics use nvidia integrated graphics,
+	 * hardcode that the 9400M is integrated */
+	if (pdev->vendor == PCI_VENDOR_ID_INTEL) {
+		return VGA_SWITCHEROO_IGD;
+	} else if (pdev->vendor == PCI_VENDOR_ID_NVIDIA &&
+		   pdev->device == 0x0863) {
+		return VGA_SWITCHEROO_IGD;
+	} else {
+		discrete = pdev;
+		return VGA_SWITCHEROO_DIS;
+	}
+}
+
+static bool gmux_client_active(enum vga_switcheroo_client_id id)
+{
+	u8 state = gmux_read8(GMUX_PORT_SWITCH_DISPLAY);
+
+	if ((id == VGA_SWITCHEROO_IGD && state == 2) ||
+	    (id == VGA_SWITCHEROO_DIS && state == 3))
+		return true;
+
+	return false;
+}
+
+static struct vga_switcheroo_handler gmux_handler = {
+	.switchto = gmux_switchto,
+	.power_state = gmux_set_power_state,
+	.init = gmux_init,
+	.get_client_id = gmux_get_client_id,
+	.client_active = gmux_client_active,
+};
+
+static void gmux_disable_interrupts(void)
+{
+	gmux_write8(GMUX_PORT_INTERRUPT_ENABLE, GMUX_INTERRUPT_DISABLE);
+}
+
+static void gmux_enable_interrupts(void)
+{
+	gmux_write8(GMUX_PORT_INTERRUPT_ENABLE, GMUX_INTERRUPT_ENABLE);
+}
+
+static int gmux_interrupt_get_status(void)
+{
+	return gmux_read8(GMUX_PORT_INTERRUPT_STATUS);
+}
+
+static void gmux_interrupt_activate_status(void)
+{
+	int old_status;
+	int new_status;
+
+	/* to reactivate interrupts write back current status */
+	old_status = gmux_read8(GMUX_PORT_INTERRUPT_STATUS);
+	gmux_write8(GMUX_PORT_INTERRUPT_STATUS, old_status);
+	new_status = gmux_read8(GMUX_PORT_INTERRUPT_STATUS);
+
+	/* status = 0 indicates active interrupts */
+	if (new_status)
+		pr_info("gmux: error: activate_status, old_status %d new_status %d\n", old_status, new_status);
+}
+
+static void gmux_notify_handler(acpi_handle device, u32 value, void *context)
+{
+	int status;
+
+	status = gmux_interrupt_get_status();
+	gmux_disable_interrupts();
+
+	gmux_interrupt_activate_status();
+	gmux_enable_interrupts();
+
+	if (status & GMUX_INTERRUPT_STATUS_POWER)
+		complete(&powerchange_done);
+}
+
 static const struct backlight_ops gmux_bl_ops = {
 	.options = BL_CORE_SUSPENDRESUME,
 	.get_brightness = gmux_get_brightness,
 	.update_status = gmux_update_status,
 };
 
+static int gmux_suspend(struct pnp_dev *dev, pm_message_t state)
+{
+	gmux_data.resume_client_id = gmux_read8(GMUX_PORT_SWITCH_DISPLAY) == 2 ?
+		VGA_SWITCHEROO_IGD : VGA_SWITCHEROO_DIS;
+	return 0;
+}
+
+static int gmux_resume(struct pnp_dev *dev)
+{
+	gmux_switchto(gmux_data.resume_client_id);
+	return 0;
+}
+
 static int __devinit gmux_probe(struct pnp_dev *pnp,
 				const struct pnp_device_id *id)
 {
-	struct apple_gmux_data *gmux_data;
 	struct resource *res;
 	struct backlight_properties props;
 	struct backlight_device *bdev;
 	u8 ver_major, ver_minor, ver_release;
+	acpi_status status;
 	int ret = -ENXIO;
 
-	gmux_data = kzalloc(sizeof(*gmux_data), GFP_KERNEL);
-	if (!gmux_data)
-		return -ENOMEM;
-	pnp_set_drvdata(pnp, gmux_data);
-
 	res = pnp_get_resource(pnp, IORESOURCE_IO, 0);
 	if (!res) {
 		pr_err("Failed to find gmux I/O resource\n");
-		goto err_free;
+		goto err_begin;
 	}
 
-	gmux_data->iostart = res->start;
-	gmux_data->iolen = res->end - res->start;
+	gmux_data.iostart = res->start;
+	gmux_data.iolen = res->end - res->start;
 
-	if (gmux_data->iolen < GMUX_MIN_IO_LEN) {
+	if (gmux_data.iolen < GMUX_MIN_IO_LEN) {
 		pr_err("gmux I/O region too small (%lu < %u)\n",
-		       gmux_data->iolen, GMUX_MIN_IO_LEN);
-		goto err_free;
+		       gmux_data.iolen, GMUX_MIN_IO_LEN);
+		goto err_begin;
 	}
 
-	if (!request_region(gmux_data->iostart, gmux_data->iolen,
+	if (!request_region(gmux_data.iostart, gmux_data.iolen,
 			    "Apple gmux")) {
 		pr_err("gmux I/O already in use\n");
-		goto err_free;
+		goto err_begin;
 	}
 
 	/*
@@ -151,9 +329,9 @@ static int __devinit gmux_probe(struct pnp_dev *pnp,
 	 * doesn't really have a gmux. Check for invalid version information
 	 * to detect this.
 	 */
-	ver_major = gmux_read8(gmux_data, GMUX_PORT_VERSION_MAJOR);
-	ver_minor = gmux_read8(gmux_data, GMUX_PORT_VERSION_MINOR);
-	ver_release = gmux_read8(gmux_data, GMUX_PORT_VERSION_RELEASE);
+	ver_major = gmux_read8(GMUX_PORT_VERSION_MAJOR);
+	ver_minor = gmux_read8(GMUX_PORT_VERSION_MINOR);
+	ver_release = gmux_read8(GMUX_PORT_VERSION_RELEASE);
 	if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
 		pr_info("gmux device not present\n");
 		ret = -ENODEV;
@@ -165,7 +343,7 @@ static int __devinit gmux_probe(struct pnp_dev *pnp,
 
 	memset(&props, 0, sizeof(props));
 	props.type = BACKLIGHT_PLATFORM;
-	props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS);
+	props.max_brightness = gmux_read32(GMUX_PORT_MAX_BRIGHTNESS);
 
 	/*
 	 * Currently it's assumed that the maximum brightness is less than
@@ -177,44 +355,73 @@ static int __devinit gmux_probe(struct pnp_dev *pnp,
 		props.max_brightness = GMUX_MAX_BRIGHTNESS;
 
 	bdev = backlight_device_register("gmux_backlight", &pnp->dev,
-					 gmux_data, &gmux_bl_ops, &props);
+					 NULL, &gmux_bl_ops, &props);
 	if (IS_ERR(bdev)) {
 		ret = PTR_ERR(bdev);
 		goto err_release;
 	}
 
-	gmux_data->bdev = bdev;
+	gmux_data.bdev = bdev;
 	bdev->props.brightness = gmux_get_brightness(bdev);
 	backlight_update_status(bdev);
 
-	/*
-	 * The backlight situation on Macs is complicated. If the gmux is
-	 * present it's the best choice, because it always works for
-	 * backlight control and supports more levels than other options.
-	 * Disable the other backlight choices.
-	 */
-	acpi_video_unregister();
-	apple_bl_unregister();
+	gmux_data.dhandle = DEVICE_ACPI_HANDLE(&pnp->dev);
+	if (!gmux_data.dhandle) {
+		pr_err("Cannot find acpi device for pnp device %s\n",
+		       dev_name(&pnp->dev));
+		goto err_release;
+	} else {
+		struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
+		acpi_get_name(gmux_data.dhandle, ACPI_SINGLE_NAME, &buf);
+		pr_info("Found acpi handle for pnp device %s: %s\n",
+			dev_name(&pnp->dev), (char *)buf.pointer);
+		kfree(buf.pointer);
+	}
+
+	status = acpi_install_notify_handler(gmux_data.dhandle,
+				ACPI_DEVICE_NOTIFY, &gmux_notify_handler, pnp);
+	if (ACPI_FAILURE(status)) {
+		pr_err("Install notify handler failed: %s\n",
+		       acpi_format_exception(status));
+		goto err_notify;
+	}
+
+	if (vga_switcheroo_register_handler(&gmux_handler))
+		goto err_register;
+
+	init_completion(&powerchange_done);
+	gmux_enable_interrupts();
 
 	return 0;
 
+err_register:
+	status = acpi_remove_notify_handler(gmux_data.dhandle,
+				     ACPI_DEVICE_NOTIFY, &gmux_notify_handler);
+	if (ACPI_FAILURE(status))
+		pr_err("Remove notify handler failed: %s\n",
+		       acpi_format_exception(status));
+err_notify:
+	backlight_device_unregister(bdev);
 err_release:
-	release_region(gmux_data->iostart, gmux_data->iolen);
-err_free:
-	kfree(gmux_data);
+	release_region(gmux_data.iostart, gmux_data.iolen);
+err_begin:
 	return ret;
 }
 
 static void __devexit gmux_remove(struct pnp_dev *pnp)
 {
-	struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
-
-	backlight_device_unregister(gmux_data->bdev);
-	release_region(gmux_data->iostart, gmux_data->iolen);
-	kfree(gmux_data);
-
-	acpi_video_register();
-	apple_bl_register();
+	acpi_status status;
+
+	vga_switcheroo_unregister_handler();
+	backlight_device_unregister(gmux_data.bdev);
+	gmux_disable_interrupts();
+	status = acpi_remove_notify_handler(gmux_data.dhandle,
+				     ACPI_DEVICE_NOTIFY, &gmux_notify_handler);
+	if (ACPI_FAILURE(status))
+		pr_err("Remove notify handler failed: %s\n",
+		       acpi_format_exception(status));
+
+	release_region(gmux_data.iostart, gmux_data.iolen);
 }
 
 static const struct pnp_device_id gmux_device_ids[] = {
@@ -227,6 +434,8 @@ static struct pnp_driver gmux_pnp_driver = {
 	.probe		= gmux_probe,
 	.remove		= __devexit_p(gmux_remove),
 	.id_table	= gmux_device_ids,
+	.suspend	= gmux_suspend,
+	.resume		= gmux_resume
 };
 
 static int __init apple_gmux_init(void)

-- 
Matthew Garrett | mjg59@...f.ucam.org
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