drm/radeon: add quirk for d3 delay during switcheroo poweron for apple macbooks

vga-switcheroo with apple-gmux does not switch correctly on my system. The PCI
configuration space is not restored correctly, resulting in MSI not working after switch.

Only useful item in dmesg is:

[   33.922807] radeon 0000:01:00.0: Refused to change power state, currently in D3

I did some testing, dumping the difference in ms between first succesful switch
from D3 to D0, and it seems that there is slightly more than 20 ms difference when
the device is re-enabled through vga-switcheroo.

So bump the re-enable d3 delay to 20 ms to handle this, which fixes msi not working
on my system after switcheroo-ing. Default d3_delay value is PCI_PM_D3_WAIT, 10 ms.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_device.c

@@ -896,6 +896,25 @@ static void radeon_check_arguments(struct radeon_device *rdev)
 	}
 }
 
+/**
+ * radeon_switcheroo_quirk_long_wakeup - return true if longer d3 delay is
+ * needed for waking up.
+ *
+ * @pdev: pci dev pointer
+ */
+static bool radeon_switcheroo_quirk_long_wakeup(struct pci_dev *pdev)
+{
+
+	/* 6600m in a macbook pro */
+	if (pdev->subsystem_vendor == PCI_VENDOR_ID_APPLE &&
+	    pdev->subsystem_device == 0x00e2) {
+		printk(KERN_INFO "radeon: quirking longer d3 wakeup delay\n");
+		return true;
+	}
+
+	return false;
+}
+
 /**
  * radeon_switcheroo_set_state - set switcheroo state
  *
@@ -910,10 +929,19 @@ static void radeon_switcheroo_set_state(struct pci_dev *pdev, enum vga_switchero
 	struct drm_device *dev = pci_get_drvdata(pdev);
 	pm_message_t pmm = { .event = PM_EVENT_SUSPEND };
 	if (state == VGA_SWITCHEROO_ON) {
+		unsigned d3_delay = dev->pdev->d3_delay;
+
 		printk(KERN_INFO "radeon: switched on\n");
 		/* don't suspend or resume card normally */
 		dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
+
+		if (d3_delay < 20 && radeon_switcheroo_quirk_long_wakeup(pdev))
+			dev->pdev->d3_delay = 20;
+
 		radeon_resume_kms(dev);
+
+		dev->pdev->d3_delay = d3_delay;
+
 		dev->switch_power_state = DRM_SWITCH_POWER_ON;
 		drm_kms_helper_poll_enable(dev);
 	} else {