drm/gma500: Fix (vblank) IRQs not working after suspend/resume

Fix gnome-shell (and other page-flip users) hanging after suspend/resume
because of the gma500's IRQs not working.

This fixes 2 problems with the IRQ handling:

1. gma_power_off() calls gma_irq_uninstall() which does a free_irq(), but
   gma_power_on() called gma_irq_preinstall() + gma_irq_postinstall() which
   do not call request_irq. Replace the pre- + post-install calls with
   gma_irq_install() which does prep + request + post.

2. After fixing 1. IRQs still do not work on a Packard Bell Dot SC (Intel
   Atom N2600, cedarview) netbook.

   Cederview uses MSI interrupts and it seems that the BIOS re-configures
   things back to normal APIC based interrupts during S3 suspend. There is
   some MSI PCI-config registers save/restore code which tries to deal with
   this, but on the Packard Bell Dot SC this is not sufficient to restore
   MSI IRQ functionality after a suspend/resume.

   Replace the PCI-config registers save/restore with pci_disable_msi() on
   suspend + pci_enable_msi() on resume. Fixing e.g. gnome-shell hanging.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220906203852.527663-4-hdegoede@redhat.com

Author: jwrdegoede

drivers/gpu/drm/gma500/cdv_device.c

@@ -581,11 +581,9 @@ static const struct psb_offset cdv_regmap[2] = {
 static int cdv_chip_setup(struct drm_device *dev)
 {
 	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
-	struct pci_dev *pdev = to_pci_dev(dev->dev);
 	INIT_WORK(&dev_priv->hotplug_work, cdv_hotplug_work_func);
 
-	if (pci_enable_msi(pdev))
-		dev_warn(dev->dev, "Enabling MSI failed!\n");
+	dev_priv->use_msi = true;
 	dev_priv->regmap = cdv_regmap;
 	gma_get_core_freq(dev);
 	psb_intel_opregion_init(dev);

drivers/gpu/drm/gma500/oaktrail_device.c

@@ -501,12 +501,9 @@ static const struct psb_offset oaktrail_regmap[2] = {
 static int oaktrail_chip_setup(struct drm_device *dev)
 {
 	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
-	struct pci_dev *pdev = to_pci_dev(dev->dev);
 	int ret;
 
-	if (pci_enable_msi(pdev))
-		dev_warn(dev->dev, "Enabling MSI failed!\n");
-
+	dev_priv->use_msi = true;
 	dev_priv->regmap = oaktrail_regmap;
 
 	ret = mid_chip_setup(dev);

drivers/gpu/drm/gma500/power.c

@@ -139,8 +139,6 @@ static void gma_suspend_pci(struct pci_dev *pdev)
 	dev_priv->regs.saveBSM = bsm;
 	pci_read_config_dword(pdev, 0xFC, &vbt);
 	dev_priv->regs.saveVBT = vbt;
-	pci_read_config_dword(pdev, PSB_PCIx_MSI_ADDR_LOC, &dev_priv->msi_addr);
-	pci_read_config_dword(pdev, PSB_PCIx_MSI_DATA_LOC, &dev_priv->msi_data);
 
 	pci_disable_device(pdev);
 	pci_set_power_state(pdev, PCI_D3hot);
@@ -168,9 +166,6 @@ static bool gma_resume_pci(struct pci_dev *pdev)
 	pci_restore_state(pdev);
 	pci_write_config_dword(pdev, 0x5c, dev_priv->regs.saveBSM);
 	pci_write_config_dword(pdev, 0xFC, dev_priv->regs.saveVBT);
-	/* restoring MSI address and data in PCIx space */
-	pci_write_config_dword(pdev, PSB_PCIx_MSI_ADDR_LOC, dev_priv->msi_addr);
-	pci_write_config_dword(pdev, PSB_PCIx_MSI_DATA_LOC, dev_priv->msi_data);
 	ret = pci_enable_device(pdev);
 
 	if (ret != 0)
@@ -223,8 +218,7 @@ int gma_power_resume(struct device *_dev)
 	mutex_lock(&power_mutex);
 	gma_resume_pci(pdev);
 	gma_resume_display(pdev);
-	gma_irq_preinstall(dev);
-	gma_irq_postinstall(dev);
+	gma_irq_install(dev);
 	mutex_unlock(&power_mutex);
 	return 0;
 }

drivers/gpu/drm/gma500/psb_drv.c

@@ -383,7 +383,7 @@ static int psb_driver_load(struct drm_device *dev, unsigned long flags)
 	PSB_WVDC32(0xFFFFFFFF, PSB_INT_MASK_R);
 	spin_unlock_irqrestore(&dev_priv->irqmask_lock, irqflags);
 
-	gma_irq_install(dev, pdev->irq);
+	gma_irq_install(dev);
 
 	dev->max_vblank_count = 0xffffff; /* only 24 bits of frame count */
 

drivers/gpu/drm/gma500/psb_drv.h

@@ -490,6 +490,7 @@ struct drm_psb_private {
 	int rpm_enabled;
 
 	/* MID specific */
+	bool use_msi;
 	bool has_gct;
 	struct oaktrail_gct_data gct_data;
 
@@ -499,10 +500,6 @@ struct drm_psb_private {
 	/* Register state */
 	struct psb_save_area regs;
 
-	/* MSI reg save */
-	uint32_t msi_addr;
-	uint32_t msi_data;
-
 	/* Hotplug handling */
 	struct work_struct hotplug_work;
 

drivers/gpu/drm/gma500/psb_irq.c

@@ -316,17 +316,24 @@ void gma_irq_postinstall(struct drm_device *dev)
 	spin_unlock_irqrestore(&dev_priv->irqmask_lock, irqflags);
 }
 
-int gma_irq_install(struct drm_device *dev, unsigned int irq)
+int gma_irq_install(struct drm_device *dev)
 {
+	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
+	struct pci_dev *pdev = to_pci_dev(dev->dev);
 	int ret;
 
-	if (irq == IRQ_NOTCONNECTED)
+	if (dev_priv->use_msi && pci_enable_msi(pdev)) {
+		dev_warn(dev->dev, "Enabling MSI failed!\n");
+		dev_priv->use_msi = false;
+	}
+
+	if (pdev->irq == IRQ_NOTCONNECTED)
 		return -ENOTCONN;
 
 	gma_irq_preinstall(dev);
 
 	/* PCI devices require shared interrupts. */
-	ret = request_irq(irq, gma_irq_handler, IRQF_SHARED, dev->driver->name, dev);
+	ret = request_irq(pdev->irq, gma_irq_handler, IRQF_SHARED, dev->driver->name, dev);
 	if (ret)
 		return ret;
 
@@ -369,6 +376,8 @@ void gma_irq_uninstall(struct drm_device *dev)
 	spin_unlock_irqrestore(&dev_priv->irqmask_lock, irqflags);
 
 	free_irq(pdev->irq, dev);
+	if (dev_priv->use_msi)
+		pci_disable_msi(pdev);
 }
 
 int gma_crtc_enable_vblank(struct drm_crtc *crtc)

drivers/gpu/drm/gma500/psb_irq.h

@@ -17,7 +17,7 @@ struct drm_device;
 
 void gma_irq_preinstall(struct drm_device *dev);
 void gma_irq_postinstall(struct drm_device *dev);
-int  gma_irq_install(struct drm_device *dev, unsigned int irq);
+int  gma_irq_install(struct drm_device *dev);
 void gma_irq_uninstall(struct drm_device *dev);
 
 int  gma_crtc_enable_vblank(struct drm_crtc *crtc);