drm/bochs: fix framebuffer setup.

The driver doesn't consider framebuffer pitch and offset, leading to a
wrong display in case offset != 0 or pitch != width * bpp.  Fix it.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: http://patchwork.freedesktop.org/patch/msgid/20190627081206.23135-1-kraxel@redhat.com

drivers/gpu/drm/bochs/bochs.h

@@ -86,7 +86,7 @@ void bochs_hw_setmode(struct bochs_device *bochs,
 void bochs_hw_setformat(struct bochs_device *bochs,
 			const struct drm_format_info *format);
 void bochs_hw_setbase(struct bochs_device *bochs,
-		      int x, int y, u64 addr);
+		      int x, int y, int stride, u64 addr);
 int bochs_hw_load_edid(struct bochs_device *bochs);
 
 /* bochs_mm.c */

drivers/gpu/drm/bochs/bochs_hw.c

@@ -255,16 +255,22 @@ void bochs_hw_setformat(struct bochs_device *bochs,
 }
 
 void bochs_hw_setbase(struct bochs_device *bochs,
-		      int x, int y, u64 addr)
+		      int x, int y, int stride, u64 addr)
 {
-	unsigned long offset = (unsigned long)addr +
+	unsigned long offset;
+	unsigned int vx, vy, vwidth;
+
+	bochs->stride = stride;
+	offset = (unsigned long)addr +
 		y * bochs->stride +
 		x * (bochs->bpp / 8);
-	int vy = offset / bochs->stride;
-	int vx = (offset % bochs->stride) * 8 / bochs->bpp;
+	vy = offset / bochs->stride;
+	vx = (offset % bochs->stride) * 8 / bochs->bpp;
+	vwidth = stride * 8 / bochs->bpp;
 
 	DRM_DEBUG_DRIVER("x %d, y %d, addr %llx -> offset %lx, vx %d, vy %d\n",
 			 x, y, addr, offset, vx, vy);
+	bochs_dispi_write(bochs, VBE_DISPI_INDEX_VIRT_WIDTH, vwidth);
 	bochs_dispi_write(bochs, VBE_DISPI_INDEX_X_OFFSET, vx);
 	bochs_dispi_write(bochs, VBE_DISPI_INDEX_Y_OFFSET, vy);
 }

drivers/gpu/drm/bochs/bochs_kms.c

@@ -36,7 +36,8 @@ static void bochs_plane_update(struct bochs_device *bochs,
 	bochs_hw_setbase(bochs,
 			 state->crtc_x,
 			 state->crtc_y,
-			 gbo->bo.offset);
+			 state->fb->pitches[0],
+			 state->fb->offsets[0] + gbo->bo.offset);
 	bochs_hw_setformat(bochs, state->fb->format);
 }