drm/mgag200: Hardware cursor support

G200 cards support, at best, 16 colour palleted images for the cursor
so we do a conversion in the cursor_set function, and reject cursors
with more than 16 colours, or cursors with partial transparency. Xorg
falls back gracefully to software cursors in this case.

We can't disable/enable the cursor hardware without causing momentary
corruption around the cursor. Instead, once the cursor is on we leave
it on, and simulate turning the cursor off by moving it
offscreen. This works well.

Since we can't disable -> update -> enable the cursors, we double
buffer cursor icons, then just move the base address that points to
the old cursor, to the new. This also works well, but uses an extra
page of memory.

The cursor buffers are lazily-allocated on first cursor_set. This is
to make sure they don't take priority over any framebuffers in case of
limited memory.

Here is a representation of how the bitmap for the cursor is mapped in G200 memory :

  Each line of color cursor use 6 Slices of 8 bytes. Slices 0 to 3
  are used for the 4bpp bitmap, slice 4 for XOR mask and slice 5 for
  AND mask. Each line has the following format:

      //      Byte 0  Byte 1  Byte 2  Byte 3  Byte 4  Byte 5  Byte 6 Byte 7
      //
      // S0:  P00-01  P02-03  P04-05  P06-07  P08-09  P10-11  P12-13 P14-15
      // S1:  P16-17  P18-19  P20-21  P22-23  P24-25  P26-27  P28-29 P30-31
      // S2:  P32-33  P34-35  P36-37  P38-39  P40-41  P42-43  P44-45 P46-47
      // S3:  P48-49  P50-51  P52-53  P54-55  P56-57  P58-59  P60-61 P62-63
      // S4:  X63-56  X55-48  X47-40  X39-32  X31-24  X23-16  X15-08 X07-00
      // S5:  A63-56  A55-48  A47-40  A39-32  A31-24  A23-16  A15-08 A07-00
      //
      //       S0 to S5      = Slices 0 to 5
      //       P00 to P63    = Bitmap - pixels 0 to 63
      //       X00 to X63    = always 0 - pixels 0 to 63
      //       A00 to A63    = transparent markers - pixels 0 to 63
      //                       1 means colour, 0 means transparent

Signed-off-by: Christopher Harvey <charvey@matrox.com>
Signed-off-by: Mathieu Larouche <mathieu.larouche@matrox.com>
Acked-by: Julia Lemire <jlemire@matrox.com>
Tested-by: Julia Lemire <jlemire@matrox.com>
Signed-off-by: Dave Airlie <airlied@gmail.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.h b/drivers/gpu/drm/mgag200/mgag200_drv.h
index bf29b2f4d68..364a05a15eb 100644
--- a/drivers/gpu/drm/mgag200/mgag200_drv.h
+++ b/drivers/gpu/drm/mgag200/mgag200_drv.h
@@ -149,6 +149,21 @@ struct mga_connector {
 	struct mga_i2c_chan *i2c;
 };
 
+struct mga_cursor {
+	/*
+	   We have to have 2 buffers for the cursor to avoid occasional
+	   corruption while switching cursor icons.
+	   If either of these is NULL, then don't do hardware cursors, and
+	   fall back to software.
+	*/
+	struct mgag200_bo *pixels_1;
+	struct mgag200_bo *pixels_2;
+	u64 pixels_1_gpu_addr, pixels_2_gpu_addr;
+	/* The currently displayed icon, this points to one of pixels_1, or pixels_2 */
+	struct mgag200_bo *pixels_current;
+	/* The previously displayed icon */
+	struct mgag200_bo *pixels_prev;
+};
 
 struct mga_mc {
 	resource_size_t			vram_size;
@@ -181,6 +196,7 @@ struct mga_device {
 	struct mga_mode_info		mode_info;
 
 	struct mga_fbdev *mfbdev;
+	struct mga_cursor cursor;
 
 	bool				suspended;
 	int				num_crtc;
@@ -273,4 +289,9 @@ int mgag200_mmap(struct file *filp, struct vm_area_struct *vma);
 int mgag200_bo_pin(struct mgag200_bo *bo, u32 pl_flag, u64 *gpu_addr);
 int mgag200_bo_unpin(struct mgag200_bo *bo);
 int mgag200_bo_push_sysram(struct mgag200_bo *bo);
+			   /* mgag200_cursor.c */
+int mga_crtc_cursor_set(struct drm_crtc *crtc, struct drm_file *file_priv,
+						uint32_t handle, uint32_t width, uint32_t height);
+int mga_crtc_cursor_move(struct drm_crtc *crtc, int x, int y);
+
 #endif				/* __MGAG200_DRV_H__ */