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Date:   Tue, 9 Jul 2019 22:55:14 -0300
From:   Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
To:     Daniel Vetter <daniel@ffwll.ch>,
        Haneen Mohammed <hamohammed.sa@gmail.com>,
        David Airlie <airlied@linux.ie>,
        Simon Ser <contact@emersion.fr>,
        Oleg Vasilev <oleg.vasilev@intel.com>
Cc:     dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: [PATCH V3] drm/vkms: Add support for vkms work without vblank
Message-ID: <20190710015514.42anrmx3r2ijaomz@smtp.gmail.com>
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Currently, vkms only work with enabled VBlank. This patch adds another
operation model that allows vkms to work 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() =3D=3D 0 checking.

Changes since V2:
 - Rebase

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 <rodrigosiqueiramelo@gmail.com>
---
 drivers/gpu/drm/vkms/vkms_crtc.c | 10 ++++++++++
 drivers/gpu/drm/vkms/vkms_drv.c  | 13 +++++++++++--
 drivers/gpu/drm/vkms/vkms_drv.h  |  2 ++
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_c=
rtc.c
index 49a8ec2cb1c1..a0c75b8c4335 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -207,12 +207,22 @@ static int vkms_crtc_atomic_check(struct drm_crtc *cr=
tc,
 static void vkms_crtc_atomic_enable(struct drm_crtc *crtc,
 				    struct drm_crtc_state *old_state)
 {
+	struct vkms_output *vkms_out =3D drm_crtc_to_vkms_output(crtc);
+
+	if (vkms_out->disable_vblank)
+		return;
+
 	drm_crtc_vblank_on(crtc);
 }
=20
 static void vkms_crtc_atomic_disable(struct drm_crtc *crtc,
 				     struct drm_crtc_state *old_state)
 {
+	struct vkms_output *vkms_out =3D drm_crtc_to_vkms_output(crtc);
+
+	if (vkms_out->disable_vblank)
+		return;
+
 	drm_crtc_vblank_off(crtc);
 }
=20
diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_dr=
v.c
index 152d7de24a76..542a002ef9d5 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -34,6 +34,11 @@ bool enable_writeback;
 module_param_named(enable_writeback, enable_writeback, bool, 0444);
 MODULE_PARM_DESC(enable_writeback, "Enable/Disable writeback connector");
=20
+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 complet=
es flips)");
+
 static const struct file_operations vkms_driver_fops =3D {
 	.owner		=3D THIS_MODULE,
 	.open		=3D drm_open,
@@ -154,9 +159,13 @@ static int __init vkms_init(void)
 	if (ret)
 		goto out_unregister;
=20
-	vkms_device->drm.irq_enabled =3D true;
+	vkms_device->output.disable_vblank =3D virtual_hw;
+	vkms_device->drm.irq_enabled =3D !virtual_hw;
+
+	if (virtual_hw)
+		DRM_INFO("Virtual hardware mode enabled");
=20
-	ret =3D drm_vblank_init(&vkms_device->drm, 1);
+	ret =3D (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_dr=
v.h
index 9ff2cd4ebf81..256e5e65c947 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -21,6 +21,7 @@
=20
 extern bool enable_cursor;
 extern bool enable_writeback;
+extern bool virtual_hw;
=20
 struct vkms_composer {
 	struct drm_framebuffer fb;
@@ -69,6 +70,7 @@ struct vkms_output {
 	struct drm_connector connector;
 	struct drm_writeback_connector wb_connector;
 	struct hrtimer vblank_hrtimer;
+	bool disable_vblank;
 	ktime_t period_ns;
 	struct drm_pending_vblank_event *event;
 	/* ordered wq for composer_work */
--=20
2.21.0

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