On Mon, Sep 03, 2018 at 12:57:54PM +0200, Gerd Hoffmann wrote:
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
Hm, not a huge fan of using driver_flags for random little quirks. I think a boolean in sturct drm_mode_config would be much better. Bonus if you also move the 30bpp hack over to that. Something like mode_config.quirk_addfb_host_byte_order and mode_config.quirk_addfb_prefer_xbgr_30bpp or whatever. That has the upside of giving us a really nice place to put a huge comment about what this is supposed to do.
I think otherwise this looks overall rather reasonable. I think the only other driver that ever cared about big endian was radeon/amdgpu. Would be good to get at least an ack from amd folks, or a "meh, stopped caring". -Daniel
/**
- 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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