drm/radeon: fix page flipping hangs on r300/r400

We've been getting reports of complete system lockups with rv3xx hw on
AGP and PCIE when running gnome-shell or kwin with compositing.

It appears the hw really doesn't like setting these registers while
stuff is running, this moves the setting of the registers into the modeset
since they aren't required to be changed anywhere else.

fixes: https://bugs.freedesktop.org/show_bug.cgi?id=35183

Reported-and-tested-by: Álmos <aaalmosss@gmail.com
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/r100.c

@@ -70,23 +70,6 @@ MODULE_FIRMWARE(FIRMWARE_R520);
 
 void r100_pre_page_flip(struct radeon_device *rdev, int crtc)
 {
-	struct radeon_crtc *radeon_crtc = rdev->mode_info.crtcs[crtc];
-	u32 tmp;
-
-	/* make sure flip is at vb rather than hb */
-	tmp = RREG32(RADEON_CRTC_OFFSET_CNTL + radeon_crtc->crtc_offset);
-	tmp &= ~RADEON_CRTC_OFFSET_FLIP_CNTL;
-	/* make sure pending bit is asserted */
-	tmp |= RADEON_CRTC_GUI_TRIG_OFFSET_LEFT_EN;
-	WREG32(RADEON_CRTC_OFFSET_CNTL + radeon_crtc->crtc_offset, tmp);
-
-	/* set pageflip to happen as late as possible in the vblank interval.
-	 * same field for crtc1/2
-	 */
-	tmp = RREG32(RADEON_CRTC_GEN_CNTL);
-	tmp &= ~RADEON_CRTC_VSTAT_MODE_MASK;
-	WREG32(RADEON_CRTC_GEN_CNTL, tmp);
-
 	/* enable the pflip int */
 	radeon_irq_kms_pflip_irq_get(rdev, crtc);
 }

drivers/gpu/drm/radeon/radeon_legacy_crtc.c

@@ -443,7 +443,7 @@ int radeon_crtc_do_set_base(struct drm_crtc *crtc,
 		       (target_fb->bits_per_pixel * 8));
 	crtc_pitch |= crtc_pitch << 16;
 
-
+	crtc_offset_cntl |= RADEON_CRTC_GUI_TRIG_OFFSET_LEFT_EN;
 	if (tiling_flags & RADEON_TILING_MACRO) {
 		if (ASIC_IS_R300(rdev))
 			crtc_offset_cntl |= (R300_CRTC_X_Y_MODE_EN |
@@ -502,6 +502,7 @@ int radeon_crtc_do_set_base(struct drm_crtc *crtc,
 	gen_cntl_val = RREG32(gen_cntl_reg);
 	gen_cntl_val &= ~(0xf << 8);
 	gen_cntl_val |= (format << 8);
+	gen_cntl_val &= ~RADEON_CRTC_VSTAT_MODE_MASK;
 	WREG32(gen_cntl_reg, gen_cntl_val);
 
 	crtc_offset = (u32)base;