drm/tilcdc: Convert to Linux IRQ interfaces

Drop the DRM IRQ midlayer in favor of Linux IRQ interfaces. DRM's
IRQ helpers are mostly useful for UMS drivers. Modern KMS drivers
don't benefit from using it.

DRM IRQ callbacks are now being called directly or inlined.

Calls to platform_get_irq() can fail with a negative errno code.
Abort initialization in this case. The DRM IRQ midlayer does not
handle this case correctly.

For most drivers, only the DRM IRQ helpers use irq_enabled from
struct drm_device. Tilcdc also uses irq_enabled to make its error
rollback work correctly. As the field will become legacy, duplicated
the state in the driver's local private structure.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210803090704.32152-12-tzimmermann@suse.de

drivers/gpu/drm/tilcdc/tilcdc_drv.c

@@ -20,7 +20,6 @@
 #include <drm/drm_fourcc.h>
 #include <drm/drm_gem_cma_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
-#include <drm/drm_irq.h>
 #include <drm/drm_mm.h>
 #include <drm/drm_probe_helper.h>
 #include <drm/drm_vblank.h>
@@ -124,6 +123,39 @@ static int cpufreq_transition(struct notifier_block *nb,
 }
 #endif
 
+static irqreturn_t tilcdc_irq(int irq, void *arg)
+{
+	struct drm_device *dev = arg;
+	struct tilcdc_drm_private *priv = dev->dev_private;
+
+	return tilcdc_crtc_irq(priv->crtc);
+}
+
+static int tilcdc_irq_install(struct drm_device *dev, unsigned int irq)
+{
+	struct tilcdc_drm_private *priv = dev->dev_private;
+	int ret;
+
+	ret = request_irq(irq, tilcdc_irq, 0, dev->driver->name, dev);
+	if (ret)
+		return ret;
+
+	priv->irq_enabled = false;
+
+	return 0;
+}
+
+static void tilcdc_irq_uninstall(struct drm_device *dev)
+{
+	struct tilcdc_drm_private *priv = dev->dev_private;
+
+	if (!priv->irq_enabled)
+		return;
+
+	free_irq(priv->irq, dev);
+	priv->irq_enabled = false;
+}
+
 /*
  * DRM operations:
  */
@@ -145,7 +177,7 @@ static void tilcdc_fini(struct drm_device *dev)
 		drm_dev_unregister(dev);
 
 	drm_kms_helper_poll_fini(dev);
-	drm_irq_uninstall(dev);
+	tilcdc_irq_uninstall(dev);
 	drm_mode_config_cleanup(dev);
 
 	if (priv->clk)
@@ -336,7 +368,12 @@ static int tilcdc_init(const struct drm_driver *ddrv, struct device *dev)
 		goto init_failed;
 	}
 
-	ret = drm_irq_install(ddev, platform_get_irq(pdev, 0));
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		goto init_failed;
+	priv->irq = ret;
+
+	ret = tilcdc_irq_install(ddev, priv->irq);
 	if (ret < 0) {
 		dev_err(dev, "failed to install IRQ handler\n");
 		goto init_failed;
@@ -360,13 +397,6 @@ static int tilcdc_init(const struct drm_driver *ddrv, struct device *dev)
 	return ret;
 }
 
-static irqreturn_t tilcdc_irq(int irq, void *arg)
-{
-	struct drm_device *dev = arg;
-	struct tilcdc_drm_private *priv = dev->dev_private;
-	return tilcdc_crtc_irq(priv->crtc);
-}
-
 #if defined(CONFIG_DEBUG_FS)
 static const struct {
 	const char *name;
@@ -454,7 +484,6 @@ DEFINE_DRM_GEM_CMA_FOPS(fops);
 
 static const struct drm_driver tilcdc_driver = {
 	.driver_features    = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
-	.irq_handler        = tilcdc_irq,
 	DRM_GEM_CMA_DRIVER_OPS,
 #ifdef CONFIG_DEBUG_FS
 	.debugfs_init       = tilcdc_debugfs_init,

drivers/gpu/drm/tilcdc/tilcdc_drv.h

@@ -46,6 +46,8 @@ struct tilcdc_drm_private {
 	struct clk *clk;         /* functional clock */
 	int rev;                 /* IP revision */
 
+	unsigned int irq;
+
 	/* don't attempt resolutions w/ higher W * H * Hz: */
 	uint32_t max_bandwidth;
 	/*
@@ -82,6 +84,7 @@ struct tilcdc_drm_private {
 
 	bool is_registered;
 	bool is_componentized;
+	bool irq_enabled;
 };
 
 /* Sub-module for display.  Since we don't know at compile time what panels