drm/msm: Get irq number within kms driver itself

The driver gets the irq number using platform_get_irq on the main kms
platform device. This works fine since both MDP4 and MDP5 currently
have a flat device hierarchy. The platform device tied with the
drm_device points to the MDP DT node in both cases.

This won't work when MDP5 supports a tree-like hierarchy. In this
case, the platform device tied to the top level drm_device is the
MDSS DT node, and the irq we need for KMS is the one generated by
MDP5, not MDSS.

Get the irq number from the MDP4/5 kms driver itself. Each driver
can later provide the irq number based on what device hierarchy it
uses.

While we're at it, call drm_irq_install only when we have a valid KMS
driver.
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/mdp/mdp4/mdp4_kms.c

@@ -436,7 +436,7 @@ struct msm_kms *mdp4_kms_init(struct drm_device *dev)
 	struct mdp4_kms *mdp4_kms;
 	struct msm_kms *kms = NULL;
 	struct msm_mmu *mmu;
-	int ret;
+	int irq, ret;
 
 	mdp4_kms = kzalloc(sizeof(*mdp4_kms), GFP_KERNEL);
 	if (!mdp4_kms) {
@@ -457,6 +457,15 @@ struct msm_kms *mdp4_kms_init(struct drm_device *dev)
 		goto fail;
 	}
 
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		ret = irq;
+		dev_err(dev->dev, "failed to get irq: %d\n", ret);
+		goto fail;
+	}
+
+	kms->irq = irq;
+
 	/* NOTE: driver for this regulator still missing upstream.. use
 	 * _get_exclusive() and ignore the error if it does not exist
 	 * (and hope that the bootloader left it on for us)

drivers/gpu/drm/msm/mdp/mdp5/mdp5_kms.c

@@ -580,7 +580,7 @@ struct msm_kms *mdp5_kms_init(struct drm_device *dev)
 	struct msm_kms *kms = NULL;
 	struct msm_mmu *mmu;
 	uint32_t major, minor;
-	int i, ret;
+	int irq, i, ret;
 
 	mdp5_kms = kzalloc(sizeof(*mdp5_kms), GFP_KERNEL);
 	if (!mdp5_kms) {
@@ -610,6 +610,15 @@ struct msm_kms *mdp5_kms_init(struct drm_device *dev)
 		goto fail;
 	}
 
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		ret = irq;
+		dev_err(dev->dev, "failed to get irq: %d\n", ret);
+		goto fail;
+	}
+
+	kms->irq = irq;
+
 	mdp5_kms->vdd = devm_regulator_get(&pdev->dev, "vdd");
 	if (IS_ERR(mdp5_kms->vdd)) {
 		ret = PTR_ERR(mdp5_kms->vdd);

drivers/gpu/drm/msm/msm_drv.c

@@ -417,12 +417,14 @@ static int msm_drm_init(struct device *dev, struct drm_driver *drv)
 		goto fail;
 	}
 
-	pm_runtime_get_sync(dev);
-	ret = drm_irq_install(ddev, platform_get_irq(pdev, 0));
-	pm_runtime_put_sync(dev);
-	if (ret < 0) {
-		dev_err(dev, "failed to install IRQ handler\n");
-		goto fail;
+	if (kms) {
+		pm_runtime_get_sync(dev);
+		ret = drm_irq_install(ddev, kms->irq);
+		pm_runtime_put_sync(dev);
+		if (ret < 0) {
+			dev_err(dev, "failed to install IRQ handler\n");
+			goto fail;
+		}
 	}
 
 	ret = drm_dev_register(ddev, 0);

drivers/gpu/drm/msm/msm_kms.h

@@ -60,6 +60,9 @@ struct msm_kms_funcs {
 
 struct msm_kms {
 	const struct msm_kms_funcs *funcs;
+
+	/* irq number to be passed on to drm_irq_install */
+	int irq;
 };
 
 static inline void msm_kms_init(struct msm_kms *kms,