[PATCH] allow 32bpp framebuffers for cirrus drm

[Zach Reizner <zachr@google.com>]

This patch allows framebuffers for cirrus to be created with
32bpp pixel formats provided that they do not violate certain
restrictions of the cirrus hardware.

Signed-off-by: Zach Reizner <zachr@google.com>
---
 drivers/gpu/drm/cirrus/cirrus_drv.h   |  2 ++
 drivers/gpu/drm/cirrus/cirrus_fbdev.c |  4 +++-
 drivers/gpu/drm/cirrus/cirrus_main.c  | 22 ++++++++++++++++++++--
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/cirrus/cirrus_drv.h b/drivers/gpu/drm/cirrus/cirrus_drv.h
index 401c890..fac475c 100644
--- a/drivers/gpu/drm/cirrus/cirrus_drv.h
+++ b/drivers/gpu/drm/cirrus/cirrus_drv.h
@@ -208,6 +208,8 @@ int cirrus_framebuffer_init(struct drm_device *dev,
 			    struct drm_mode_fb_cmd2 *mode_cmd,
 			    struct drm_gem_object *obj);
 
+bool cirrus_check_framebuffer(int width, int height, int bpp, int pitch);
+
 				/* cirrus_display.c */
 int cirrus_modeset_init(struct cirrus_device *cdev);
 void cirrus_modeset_fini(struct cirrus_device *cdev);
diff --git a/drivers/gpu/drm/cirrus/cirrus_fbdev.c b/drivers/gpu/drm/cirrus/cirrus_fbdev.c
index 2a135f2..4a0756c 100644
--- a/drivers/gpu/drm/cirrus/cirrus_fbdev.c
+++ b/drivers/gpu/drm/cirrus/cirrus_fbdev.c
@@ -146,8 +146,10 @@ static int cirrusfb_create_object(struct cirrus_fbdev *afbdev,
 	int ret = 0;
 	drm_fb_get_bpp_depth(mode_cmd->pixel_format, &depth, &bpp);
 
-	if (bpp > 24)
+	if (!cirrus_check_framebuffer(mode_cmd->width, mode_cmd->height, bpp,
+				      mode_cmd->pitches[0]))
 		return -EINVAL;
+
 	size = mode_cmd->pitches[0] * mode_cmd->height;
 	ret = cirrus_gem_create(dev, size, true, &gobj);
 	if (ret)
diff --git a/drivers/gpu/drm/cirrus/cirrus_main.c b/drivers/gpu/drm/cirrus/cirrus_main.c
index 99c1983..029f9e9 100644
--- a/drivers/gpu/drm/cirrus/cirrus_main.c
+++ b/drivers/gpu/drm/cirrus/cirrus_main.c
@@ -55,8 +55,9 @@ cirrus_user_framebuffer_create(struct drm_device *dev,
 	u32 bpp, depth;
 
 	drm_fb_get_bpp_depth(mode_cmd->pixel_format, &depth, &bpp);
-	/* cirrus can't handle > 24bpp framebuffers at all */
-	if (bpp > 24)
+
+	if (!cirrus_check_framebuffer(mode_cmd->width, mode_cmd->height,
+				      bpp, mode_cmd->pitches[0]))
 		return ERR_PTR(-EINVAL);
 
 	obj = drm_gem_object_lookup(dev, filp, mode_cmd->handles[0]);
@@ -307,3 +308,20 @@ out_unlock:
 	return ret;
 
 }
+
+bool cirrus_check_framebuffer(int width, int height, int bpp, int pitch)
+{
+	const int max_pitch = 0x1FF << 3; /* (4096 - 1) & ~111b bytes */
+	const int max_size = 0x400000; /* 4MB */
+
+	if (bpp > 32)
+		return false;
+
+	if (pitch > max_pitch)
+		return false;
+
+	if (pitch * height > max_size)
+		return false;
+
+	return true;
+}
-- 
2.1.0.rc2.206.gedb03e5