nouveau: Support Optimus models for vga_switcheroo

Newer nVidia cards with Optimus do not support/use the DSM switching functions.
Instead, it require a DSM function to be called prior to bringing a device into
D3 state. No other _DSM calls are necessary before/after enabling/disabling a
device. Switching between discrete and integrated GPU is not supported by
this Optimus _DSM call, therefore return on the switching method.

Signed-off-by: Peter Lekensteyn <[e-mail]>
Signed-off-by: Dave Airlie <[e-mail]>

drivers/gpu/drm/nouveau/nouveau_acpi.c

···
 #define NOUVEAU_DSM_POWER_STAMINA 0x02
 
 #define NOUVEAU_DSM_OPTIMUS_FN 0x1A
+#define NOUVEAU_DSM_OPTIMUS_ARGS 0x03000001
+
 static struct nouveau_dsm_priv {
 	bool dsm_detected;
 	bool optimus_detected;
···
 	struct acpi_object_list input;
 	union acpi_object params[4];
 	union acpi_object *obj;
-	int err;
+	int i, err;
+	char args_buff[4];
 
 	input.count = 4;
 	input.pointer = params;
···
 	params[2].type = ACPI_TYPE_INTEGER;
 	params[2].integer.value = func;
 	params[3].type = ACPI_TYPE_BUFFER;
-	params[3].buffer.length = 0;
+	params[3].buffer.length = 4;
+	/* ACPI is little endian, AABBCCDD becomes {DD,CC,BB,AA} */
+	for (i = 0; i < 4; i++)
+		args_buff[i] = (arg >> i * 8) & 0xFF;
+	params[3].buffer.pointer = args_buff;
 
 	err = acpi_evaluate_object(handle, "_DSM", &input, &output);
 	if (err) {
···
 
 static int nouveau_dsm_switchto(enum vga_switcheroo_client_id id)
 {
+	/* perhaps the _DSM functions are mutually exclusive, but prepare for
+	 * the future */
+	if (!nouveau_dsm_priv.dsm_detected && nouveau_dsm_priv.optimus_detected)
+		return 0;
 	if (id == VGA_SWITCHEROO_IGD)
 		return nouveau_dsm_switch_mux(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_LED_STAMINA);
 	else
···
 				   enum vga_switcheroo_state state)
 {
 	if (id == VGA_SWITCHEROO_IGD)
+		return 0;
+
+	/* Optimus laptops have the card already disabled in
+	 * nouveau_switcheroo_set_state */
+	if (!nouveau_dsm_priv.dsm_detected && nouveau_dsm_priv.optimus_detected)
 		return 0;
 
 	return nouveau_dsm_set_discrete_state(nouveau_dsm_priv.dhandle, state);
···
 	}
 
 	if (vga_count == 2 && has_dsm && guid_valid) {
-		acpi_get_name(nouveau_dsm_priv.dhandle, ACPI_FULL_PATHNAME, &buffer);
+		acpi_get_name(nouveau_dsm_priv.dhandle, ACPI_FULL_PATHNAME,
+			&buffer);
 		printk(KERN_INFO "VGA switcheroo: detected DSM switching method %s handle\n",
-		       acpi_method_name);
+			acpi_method_name);
 		nouveau_dsm_priv.dsm_detected = true;
 		ret = true;
 	}
 
-	if (has_optimus == 1)
+	if (has_optimus == 1) {
+		acpi_get_name(nouveau_dsm_priv.dhandle, ACPI_FULL_PATHNAME,
+			&buffer);
+		printk(KERN_INFO "VGA switcheroo: detected Optimus DSM method %s handle\n",
+			acpi_method_name);
 		nouveau_dsm_priv.optimus_detected = true;
+		ret = true;
+	}
 
 	return ret;
 }
···
 		return;
 
 	vga_switcheroo_register_handler(&nouveau_dsm_handler);
+}
+
+/* Must be called for Optimus models before the card can be turned off */
+void nouveau_switcheroo_optimus_dsm(void)
+{
+	u32 result = 0;
+	if (!nouveau_dsm_priv.optimus_detected)
+		return;
+
+	nouveau_optimus_dsm(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_OPTIMUS_FN,
+		NOUVEAU_DSM_OPTIMUS_ARGS, &result);
 }
 
 void nouveau_unregister_dsm_handler(void)

drivers/gpu/drm/nouveau/nouveau_drv.h

···
 #if defined(CONFIG_ACPI)
 void nouveau_register_dsm_handler(void);
 void nouveau_unregister_dsm_handler(void);
+void nouveau_switcheroo_optimus_dsm(void);
 int nouveau_acpi_get_bios_chunk(uint8_t *bios, int offset, int len);
 bool nouveau_acpi_rom_supported(struct pci_dev *pdev);
 int nouveau_acpi_edid(struct drm_device *, struct drm_connector *);
 #else
 static inline void nouveau_register_dsm_handler(void) {}
 static inline void nouveau_unregister_dsm_handler(void) {}
+static inline void nouveau_switcheroo_optimus_dsm(void) {}
 static inline bool nouveau_acpi_rom_supported(struct pci_dev *pdev) { return false; }
 static inline int nouveau_acpi_get_bios_chunk(uint8_t *bios, int offset, int len) { return -EINVAL; }
 static inline int nouveau_acpi_edid(struct drm_device *dev, struct drm_connector *connector) { return -EINVAL; }

drivers/gpu/drm/nouveau/nouveau_state.c

···
 		printk(KERN_ERR "VGA switcheroo: switched nouveau off\n");
 		dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
 		drm_kms_helper_poll_disable(dev);
+		nouveau_switcheroo_optimus_dsm();
 		nouveau_pci_suspend(pdev, pmm);
 		dev->switch_power_state = DRM_SWITCH_POWER_OFF;
 	}