drm/nouveau: prefer XBGR2101010 for addfb ioctl

Nouveau only exposes support for XBGR2101010. Prior to the atomic
conversion, drm would pass in the wrong format in the framebuffer, but
it was always ignored -- both userspace (xf86-video-nouveau) and the
kernel driver agreed on the layout, so the fact that the format was
wrong didn't matter.

With the atomic conversion, nouveau all of a sudden started caring about
the exact format, and so the previously-working code in
xf86-video-nouveau no longer functioned since the (internally-assigned)
format from the addfb ioctl was wrong.

This change adds infrastructure to allow a drm driver to specify that it
prefers the XBGR format variant for the addfb ioctl, and makes nouveau's
nv50 display driver set it. (Prior gens had no support for 30bpp at all.)

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Cc: stable@vger.kernel.org # v4.10+
Acked-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180203191123.31507-1-imirkin@alum.mit.edu

3 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_framebuffer.c b/drivers/gpu/drm/drm_framebuffer.c
index 5a13ff29f4f0..c0530a1af5e3 100644
--- a/drivers/gpu/drm/drm_framebuffer.c
+++ b/drivers/gpu/drm/drm_framebuffer.c
@@ -121,6 +121,10 @@ int drm_mode_addfb(struct drm_device *dev,
         r.pixel_format = drm_mode_legacy_fb_format(or->bpp, or->depth);
         r.handles[0] = or->handle;
 
+        if (r.pixel_format == DRM_FORMAT_XRGB2101010 &&
+            dev->driver->driver_features & DRIVER_PREFER_XBGR_30BPP)
+                r.pixel_format = DRM_FORMAT_XBGR2101010;
+
         ret = drm_mode_addfb2(dev, &r, file_priv);
         if (ret)
                 return ret;
diff --git a/drivers/gpu/drm/nouveau/nv50_display.c b/drivers/gpu/drm/nouveau/nv50_display.c
index dd8d4352ed99..caddce88d2d8 100644
--- a/drivers/gpu/drm/nouveau/nv50_display.c
+++ b/drivers/gpu/drm/nouveau/nv50_display.c
@@ -4477,6 +4477,7 @@ nv50_display_create(struct drm_device *dev)
         nouveau_display(dev)->fini = nv50_display_fini;
         disp->disp = &nouveau_display(dev)->disp;
         dev->mode_config.funcs = &nv50_disp_func;
+        dev->driver->driver_features |= DRIVER_PREFER_XBGR_30BPP;
         if (nouveau_atomic)
                 dev->driver->driver_features |= DRIVER_ATOMIC;
 
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index d32b688eb346..d23dcdd1bd95 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -56,6 +56,7 @@ struct drm_printer;
 #define DRIVER_ATOMIC                   0x10000
 #define DRIVER_KMS_LEGACY_CONTEXT       0x20000
 #define DRIVER_SYNCOBJ                  0x40000
+#define DRIVER_PREFER_XBGR_30BPP        0x80000
 
 /**
  * struct drm_driver - DRM driver structure