Add kernel 5.15 for RPI4 support

root/target/linux/bcm27xx/patches-5.15/0242-media-bcm2835-unicam-Always-service-interrupts.patch

@@ -0,0 +1,56 @@
+From b9654e991c61643e2aac8525c7d0baceade29133 Mon Sep 17 00:00:00 2001
+From: Dave Stevenson <dave.stevenson@raspberrypi.com>
+Date: Wed, 13 May 2020 18:28:27 +0100
+Subject: [PATCH 242/634] media: bcm2835-unicam: Always service interrupts
+
+From when bringing up the driver, there was a check in the isr
+to ignore interrupts (claiming them handled) should the driver
+not be streaming.
+
+The VPU now will not register a camera driver if it finds a
+CSI2 node enabled in device tree, therefore this flawed check is
+redundant.
+
+https://github.com/raspberrypi/linux/issues/3602
+
+Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
+---
+ drivers/media/platform/bcm2835/bcm2835-unicam.c | 15 ---------------
+ 1 file changed, 15 deletions(-)
+
+diff --git a/drivers/media/platform/bcm2835/bcm2835-unicam.c b/drivers/media/platform/bcm2835/bcm2835-unicam.c
+index 92e5deb4c6fd..52a534d932bf 100644
+--- a/drivers/media/platform/bcm2835/bcm2835-unicam.c
++++ b/drivers/media/platform/bcm2835/bcm2835-unicam.c
+@@ -766,12 +766,6 @@ static int unicam_all_nodes_streaming(struct unicam_device *dev)
+ 	return ret;
+ }
+ 
+-static int unicam_all_nodes_disabled(struct unicam_device *dev)
+-{
+-	return !dev->node[IMAGE_PAD].streaming &&
+-	       !dev->node[METADATA_PAD].streaming;
+-}
+-
+ static void unicam_queue_event_sof(struct unicam_device *unicam)
+ {
+ 	struct v4l2_event event = {
+@@ -801,15 +795,6 @@ static irqreturn_t unicam_isr(int irq, void *dev)
+ 	u64 ts;
+ 	int i;
+ 
+-	/*
+-	 * Don't service interrupts if not streaming.
+-	 * Avoids issues if the VPU should enable the
+-	 * peripheral without the kernel knowing (that
+-	 * shouldn't happen, but causes issues if it does).
+-	 */
+-	if (unicam_all_nodes_disabled(unicam))
+-		return IRQ_HANDLED;
+-
+ 	sta = reg_read(cfg, UNICAM_STA);
+ 	/* Write value back to clear the interrupts */
+ 	reg_write(cfg, UNICAM_STA, sta);
+-- 
+2.33.1
+