drm/radeon: Fix rs400_gpu_init for ATI mobility radeon Xpress 200M

num_gb_pipes was set to a wrong value using r420_pipe_config

This have lead to HyperZ glitches on fast Z clearing.

Closes: https://bugs.freedesktop.org/show_bug.cgi?id=110897
Reviewed-by: Marek Olšák <[e-mail]>
Signed-off-by: Richard Thier <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>
(cherry picked from commit 044e59a85c4d84e3c8d004c486e5c479640563a6)
Cc: [e-mail]

drivers/gpu/drm/radeon/r300.c

···
 	return -1;
 }
 
-static void r300_gpu_init(struct radeon_device *rdev)
+/* rs400_gpu_init also calls this! */
+void r300_gpu_init(struct radeon_device *rdev)
 {
 	uint32_t gb_tile_config, tmp;
 

drivers/gpu/drm/radeon/radeon_asic.h

···
  */
 extern int r300_init(struct radeon_device *rdev);
 extern void r300_fini(struct radeon_device *rdev);
+extern void r300_gpu_init(struct radeon_device *rdev);
 extern int r300_suspend(struct radeon_device *rdev);
 extern int r300_resume(struct radeon_device *rdev);
 extern int r300_asic_reset(struct radeon_device *rdev, bool hard);

drivers/gpu/drm/radeon/rs400.c

···
 
 static void rs400_gpu_init(struct radeon_device *rdev)
 {
-	/* FIXME: is this correct ? */
-	r420_pipes_init(rdev);
+	/* Earlier code was calling r420_pipes_init and then
+	 * rs400_mc_wait_for_idle(rdev). The problem is that
+	 * at least on my Mobility Radeon Xpress 200M RC410 card
+	 * that ends up in this code path ends up num_gb_pipes == 3
+	 * while the card seems to have only one pipe. With the
+	 * r420 pipe initialization method.
+	 *
+	 * Problems shown up as HyperZ glitches, see:
+	 * https://bugs.freedesktop.org/show_bug.cgi?id=110897
+	 *
+	 * Delegating initialization to r300 code seems to work
+	 * and results in proper pipe numbers. The rs400 cards
+	 * are said to be not r400, but r300 kind of cards.
+	 */
+	r300_gpu_init(rdev);
+
 	if (rs400_mc_wait_for_idle(rdev)) {
 		pr_warn("rs400: Failed to wait MC idle while programming pipes. Bad things might happen. %08x\n",
 			RREG32(RADEON_MC_STATUS));