bcm27xx: add support for linux v5.15

Build system: x86_64
Build-tested: bcm2708, bcm2709, bcm2710, bcm2711
Run-tested: bcm2708/RPiB+, bcm2709/RPi3B, bcm2710/RPi3B, bcm2711/RPi4B

Signed-off-by: Marty Jones <mj8263788@gmail.com>
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/target/linux/bcm27xx/patches-5.15/950-0431-drm-vc4-Change-the-default-DPI-format-to-being-18bpp.patch b/target/linux/bcm27xx/patches-5.15/950-0431-drm-vc4-Change-the-default-DPI-format-to-being-18bpp.patch
new file mode 100644
index 0000000000..b278eb4dd2
--- /dev/null
+++ b/target/linux/bcm27xx/patches-5.15/950-0431-drm-vc4-Change-the-default-DPI-format-to-being-18bpp.patch
@@ -0,0 +1,34 @@
+From bf6ce41170822705037cc070b89a85ac4e6a4645 Mon Sep 17 00:00:00 2001
+From: Dave Stevenson <dave.stevenson@raspberrypi.com>
+Date: Fri, 12 Feb 2021 17:31:37 +0000
+Subject: [PATCH] drm/vc4: Change the default DPI format to being
+ 18bpp, not 24.
+
+DPI hasn't really been used up until now, so the default has
+been meaningless.
+In theory we should be able to pass the desired format for the
+adjacent bridge chip through, but framework seems to be missing
+for that.
+
+As the main device to use DPI is the VGA666 or Adafruit Kippah,
+both of which use RGB666, change the default to being RGB666 instead
+of RGB888.
+
+Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
+---
+ drivers/gpu/drm/vc4/vc4_dpi.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+--- a/drivers/gpu/drm/vc4/vc4_dpi.c
++++ b/drivers/gpu/drm/vc4/vc4_dpi.c
+@@ -188,8 +188,8 @@ static void vc4_dpi_encoder_enable(struc
+ 			break;
+ 		}
+ 	} else {
+-		/* Default to 24bit if no connector found. */
+-		dpi_c |= VC4_SET_FIELD(DPI_FORMAT_24BIT_888_RGB, DPI_FORMAT);
++		/* Default to 18bit if no connector found. */
++		dpi_c |= VC4_SET_FIELD(DPI_FORMAT_18BIT_666_RGB_1, DPI_FORMAT);
+ 	}
+ 
+ 	if (mode->flags & DRM_MODE_FLAG_NHSYNC)