[PATCH xserver] modesetting: only fall back to drmModeSetCursor() on -EINVAL

[Michael Thayer]

This change effectively reverts commit 074cf58.  We were falling back from
drmModeSetCursor2() to drmModeSetCursor() whenever the first failed.  This
fall-back only makes sense on pre-mid-2013 kernels which implemented the
cursor_set hook but not cursor_set2, and in this case the call to
drmModeSetCursor2() will always return -EINVAL.  Specifically, a return
value of -ENXIO usually means that neither are supported.

Signed-off-by: Michael Thayer <michael.thayer at oracle.com>
---
1) Tested that hardware cursors still work with the patch applied.
2) Tested in gdb that the expected path is taken when drmModeSetCursor2()
   returns -EINVAL.

 hw/xfree86/drivers/modesetting/drmmode_display.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/hw/xfree86/drivers/modesetting/drmmode_display.c b/hw/xfree86/drivers/modesetting/drmmode_display.c
index 6b933e4..41810d9 100644
--- a/hw/xfree86/drivers/modesetting/drmmode_display.c
+++ b/hw/xfree86/drivers/modesetting/drmmode_display.c
@@ -768,11 +768,15 @@ drmmode_set_cursor(xf86CrtcPtr crtc)
         if (!ret)
             return TRUE;
 
-        drmmode_crtc->set_cursor2_failed = TRUE;
+        /* -EINVAL can mean that an old kernel supports drmModeSetCursor but
+         * not drmModeSetCursor2, though it can mean other things too. */
+        if (ret == -EINVAL)
+            drmmode_crtc->set_cursor2_failed = TRUE;
     }
 
-    ret = drmModeSetCursor(drmmode->fd, drmmode_crtc->mode_crtc->crtc_id, handle,
-                           ms->cursor_width, ms->cursor_height);
+    if (ret == -EINVAL)
+        ret = drmModeSetCursor(drmmode->fd, drmmode_crtc->mode_crtc->crtc_id,
+                               handle, ms->cursor_width, ms->cursor_height);
 
     if (ret) {
         xf86CrtcConfigPtr xf86_config = XF86_CRTC_CONFIG_PTR(crtc->scrn);
-- 
2.9.3