[V2] drm/vkms: Add support for vkms work without vblank

Commit Message

Rodrigo Siqueira Aug. 23, 2018, 5:34 p.m. UTC

Currently, vkms needs VBlank to work well. This patch adds another
operation model that make vkms works without VBlank support. In this
scenario, vblank signaling is faked by calling drm_send_vblank_event()
in vkms_crtc_atomic_flush(); this approach works due to the
drm_vblank_get() == 0 verification.

Changes since V1:
  Daniel Vetter:
  - Change module parameter name from disablevblank to virtual_hw
  - Improve parameter description
  - Improve commit message

Signed-off-by: Rodrigo Siqueira <[e-mail]>
---
 drivers/gpu/drm/vkms/vkms_crtc.c | 10 ++++++++++
 drivers/gpu/drm/vkms/vkms_drv.c  | 13 +++++++++++--
 drivers/gpu/drm/vkms/vkms_drv.h  |  1 +
 3 files changed, 22 insertions(+), 2 deletions(-)

Patch

diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index bfe6e0312cc4..001fa5c1d326 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -145,12 +145,22 @@  static const struct drm_crtc_funcs vkms_crtc_funcs = {
 static void vkms_crtc_atomic_enable(struct drm_crtc *crtc,
 				    struct drm_crtc_state *old_state)
 {
+	struct vkms_output *vkms_out = drm_crtc_to_vkms_output(crtc);
+
+	if (vkms_out->disable_vblank)
+		return;
+
 	drm_crtc_vblank_on(crtc);
 }
 
 static void vkms_crtc_atomic_disable(struct drm_crtc *crtc,
 				     struct drm_crtc_state *old_state)
 {
+	struct vkms_output *vkms_out = drm_crtc_to_vkms_output(crtc);
+
+	if (vkms_out->disable_vblank)
+		return;
+
 	drm_crtc_vblank_off(crtc);
 }
 
diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index 5d78bd97e69c..0b6569ee9dcc 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -21,6 +21,11 @@ 
 
 static struct vkms_device *vkms_device;
 
+static bool virtual_hw;
+module_param_named(virtual_hw, virtual_hw, bool, 0444);
+MODULE_PARM_DESC(virtual_hw,
+		 "Enable virtual hardware mode (disables vblanks and immediately completes flips)");
+
 static const struct file_operations vkms_driver_fops = {
 	.owner		= THIS_MODULE,
 	.open		= drm_open,
@@ -105,9 +110,13 @@  static int __init vkms_init(void)
 		goto out_fini;
 	}
 
-	vkms_device->drm.irq_enabled = true;
+	vkms_device->output.disable_vblank = virtual_hw;
+	vkms_device->drm.irq_enabled = !virtual_hw;
+
+	if (virtual_hw)
+		DRM_INFO("Virtual Hardware mode enabled");
 
-	ret = drm_vblank_init(&vkms_device->drm, 1);
+	ret = (virtual_hw) ? 0 : drm_vblank_init(&vkms_device->drm, 1);
 	if (ret) {
 		DRM_ERROR("Failed to vblank\n");
 		goto out_fini;
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index f156c930366a..9ee862e6f7e5 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -52,6 +52,7 @@  struct vkms_output {
 	struct drm_encoder encoder;
 	struct drm_connector connector;
 	struct hrtimer vblank_hrtimer;
+	bool disable_vblank;
 	ktime_t period_ns;
 	struct drm_pending_vblank_event *event;
 	bool crc_enabled;