From 1f85535cd04cb0b135971df9dcfd51749c9783f3 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Fri, 18 Jan 2019 13:20:07 +0100
Subject: [PATCH] drm/qxl: move qxl_primary_apply_cursor to correct place
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The qxl device ties the cursor to the primary surface. Therefore
calling qxl_io_destroy_primary() and qxl_io_create_primary() to switch
the framebuffer causes the cursor information being lost and the driver
must re-apply it.
The correct call order to do that is qxl_io_destroy_primary() +
qxl_io_create_primary() + qxl_primary_apply_cursor().
The old code did qxl_io_destroy_primary() + qxl_primary_apply_cursor() +
qxl_io_create_primary(). Due to qxl_primary_apply_cursor request being
queued in a ringbuffer and qxl_io_create_primary() trapping to the
hypervisor instantly there is a high chance that qxl_io_create_primary()
is processed first even with the wrong call order. But it's racy and
thus not reliable.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20190118122020.27596-11-kraxel@redhat.com
---
drivers/gpu/drm/qxl/qxl_display.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/qxl/qxl_display.c b/drivers/gpu/drm/qxl/qxl_display.c
index c4dd71a80c2fa..6180b4a714b6f 100644
--- a/drivers/gpu/drm/qxl/qxl_display.c
+++ b/drivers/gpu/drm/qxl/qxl_display.c
@@ -533,7 +533,6 @@ static void qxl_primary_atomic_update(struct drm_plane *plane,
.x2 = plane->state->fb->width,
.y2 = plane->state->fb->height
};
- int ret;
bool same_shadow = false;
if (old_state->fb) {
@@ -554,16 +553,13 @@ static void qxl_primary_atomic_update(struct drm_plane *plane,
if (!same_shadow)
qxl_io_destroy_primary(qdev);
bo_old->is_primary = false;
-
- ret = qxl_primary_apply_cursor(plane);
- if (ret)
- DRM_ERROR(
- "could not set cursor after creating primary");
}
if (!bo->is_primary) {
- if (!same_shadow)
+ if (!same_shadow) {
qxl_io_create_primary(qdev, 0, bo);
+ qxl_primary_apply_cursor(plane);
+ }
bo->is_primary = true;
}