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Subject[PATCH 3/5] drm: fix drm_mode_addfb() on big endian machines.
Date
Userspace on big endian machhines typically expects the ADDFB ioctl
returns a big endian framebuffer. drm_mode_addfb() will call
drm_mode_addfb2() unconditionally with little endian DRM_FORMAT_*
values though, which is wrong. This patch fixes that.

Drivers (both kernel and xorg) have quirks in place to deal with the
broken drm_mode_addfb() behavior. Because of this we can't just change
drm_mode_addfb() behavior for everybody without breaking things. So add
a new driver feature flag DRIVER_PREFER_HOST_BYTE_ORDER, so drivers can
opt-in.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
include/drm/drm_drv.h | 1 +
drivers/gpu/drm/drm_framebuffer.c | 11 +++++++++++
2 files changed, 12 insertions(+)

diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index 46a8009784..9cf12596cd 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -57,6 +57,7 @@ struct drm_printer;
#define DRIVER_KMS_LEGACY_CONTEXT 0x20000
#define DRIVER_SYNCOBJ 0x40000
#define DRIVER_PREFER_XBGR_30BPP 0x80000
+#define DRIVER_PREFER_HOST_BYTE_ORDER 0x100000

/**
* struct drm_driver - DRM driver structure
diff --git a/drivers/gpu/drm/drm_framebuffer.c b/drivers/gpu/drm/drm_framebuffer.c
index 88758096d5..ccbda8a2e9 100644
--- a/drivers/gpu/drm/drm_framebuffer.c
+++ b/drivers/gpu/drm/drm_framebuffer.c
@@ -124,6 +124,17 @@ int drm_mode_addfb(struct drm_device *dev, struct drm_mode_fb_cmd *or,
dev->driver->driver_features & DRIVER_PREFER_XBGR_30BPP)
r.pixel_format = DRM_FORMAT_XBGR2101010;

+ if (dev->driver->driver_features & DRIVER_PREFER_HOST_BYTE_ORDER) {
+ if (r.pixel_format == DRM_FORMAT_XRGB8888)
+ r.pixel_format = DRM_FORMAT_HOST_XRGB8888;
+ if (r.pixel_format == DRM_FORMAT_ARGB8888)
+ r.pixel_format = DRM_FORMAT_HOST_ARGB8888;
+ if (r.pixel_format == DRM_FORMAT_RGB565)
+ r.pixel_format = DRM_FORMAT_HOST_RGB565;
+ if (r.pixel_format == DRM_FORMAT_XRGB1555)
+ r.pixel_format = DRM_FORMAT_HOST_XRGB1555;
+ }
+
ret = drm_mode_addfb2(dev, &r, file_priv);
if (ret)
return ret;
--
2.9.3
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