On CHV pipe C when the cursor is visible with a negative X coordinate
a FIFO Underrun will occur. The kernel worked around this by disallowing
cursor updates on pipe C at negative X coordinates when the cursor is
visible.

This was done in the following kernel commit:
commit ef8dd37af85a8f37ca3a29074647511e52c56181
Author: Ville Syrjälä <ville.syrj...@linux.intel.com>
Date:   Fri Dec 18 19:24:39 2015 +0200

    drm/i915: Workaround CHV pipe C cursor fail

kms_chv_cursor_fail was created to test this issue, but it also happens
in kms_cursor_crc, so workaround it there too.

Signed-off-by: Maarten Lankhorst <maarten.lankho...@linux.intel.com>
Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
 tests/kms_cursor_crc.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/tests/kms_cursor_crc.c b/tests/kms_cursor_crc.c
index 0940752b8c40..4c5e00c074a5 100644
--- a/tests/kms_cursor_crc.c
+++ b/tests/kms_cursor_crc.c
@@ -106,6 +106,34 @@ static void cursor_disable(data_t *data)
        igt_plane_set_fb(cursor, NULL);
 }
 
+static bool chv_cursor_broken(data_t *data, int x)
+{
+       /*
+        * CHV gets a FIFO underrun on pipe C when cursor x coordinate
+        * is negative and the cursor visible.
+        *
+        * i915 is fixed to return -EINVAL on cursor updates with those
+        * negative coordinates, so require cursor update to fail with
+        * -EINVAL in that case.
+        *
+        * See also kms_chv_cursor_fail.c
+        */
+       if (x >= 0)
+               return false;
+
+       return IS_CHERRYVIEW(data->devid) && data->pipe == PIPE_C;
+}
+
+static bool cursor_visible(data_t *data, int x, int y)
+{
+       if (x + data->curw <= 0 || y + data->curh <= 0)
+               return false;
+
+       if (x >= data->screenw || y >= data->screenh)
+               return false;
+
+       return true;
+}
 
 static void do_single_test(data_t *data, int x, int y)
 {
@@ -114,6 +142,7 @@ static void do_single_test(data_t *data, int x, int y)
        igt_crc_t crc, ref_crc;
        igt_plane_t *cursor;
        cairo_t *cr = igt_get_cairo_ctx(data->drm_fd, &data->primary_fb);
+       int ret = 0;
 
        igt_print_activity();
 
@@ -122,7 +151,17 @@ static void do_single_test(data_t *data, int x, int y)
        cursor_enable(data);
        cursor = igt_output_get_plane_type(data->output, DRM_PLANE_TYPE_CURSOR);
        igt_plane_set_position(cursor, x, y);
+
+       if (chv_cursor_broken(data, x) && cursor_visible(data, x, y)) {
+               ret = igt_display_try_commit2(display, COMMIT_LEGACY);
+               igt_assert_eq(ret, -EINVAL);
+               igt_plane_set_position(cursor, 0, y);
+
+               return;
+       }
+
        igt_display_commit(display);
+
        igt_wait_for_vblank(data->drm_fd, data->pipe);
        igt_pipe_crc_collect_crc(pipe_crc, &crc);
 
-- 
2.11.0

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