[PATCH V2 1/2] drm/vkms: Add support for virtual hardware mode

Sumera Priyadarsini
2021-03-03T17:11:41Z

Add a virtual hardware or vblank-less mode as a module to enable
VKMS to emulate virtual graphic drivers.

Two new functions vkms_composer_common() and vkms_crtc_composer() have
been added. The actual plane composition work has been moved to
vkms_composer_common() which is called by both vkms_composer_worker()
and vkms_crtc_composer(). vkms_crtc_composer() is used in case of
vblank mode and is called directly in the atomic hook in
vkms_atomic_begin(). However, some crc captures still use vblanks
which causes the crc-based igt tests to crash. Currently, I am unsure
about how to approach one-shot implementation of crc reads so I am
still working on that.

The patch is based on Rodrigo Siqueira's
patch(https://patchwork.freedesktop.org/patch/316851/?series=48469&rev=3)
and the ensuing review.

Signed-off-by: Sumera Priyadarsini <sylphrenadin@gmail.com>
----
Changes in V2:
- Remove spinlock across 'vkms_output->lock' in vkms_crtc.c(Daniel)
- Add vkms_composer_common() (Daniel)
---
drivers/gpu/drm/vkms/vkms_composer.c | 88 +++++++++++++++++-----------
drivers/gpu/drm/vkms/vkms_crtc.c | 24 ++++++--
drivers/gpu/drm/vkms/vkms_drv.c | 18 ++++--
drivers/gpu/drm/vkms/vkms_drv.h | 4 ++
4 files changed, 91 insertions(+), 43 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index 66c6842d70db..df5b946f001f 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -169,6 +169,44 @@ static int compose_planes(void **vaddr_out,
return 0;
}

+int vkms_composer_common(struct vkms_crtc_state *crtc_state,
+ struct vkms_output *out, bool wb_pending, uint32_t *crc32)
+{
+ struct vkms_composer *primary_composer = NULL;
+ struct vkms_composer *cursor_composer = NULL;
+ void *vaddr_out = NULL;
+ int ret;
+
+ if (crtc_state->num_active_planes >= 1)
+ primary_composer = crtc_state->active_planes[0]->composer;
+ if (crtc_state->num_active_planes == 2)
+ cursor_composer = crtc_state->active_planes[1]->composer;
+ if (!primary_composer)
+ return -EINVAL;
+ if (wb_pending)
+ vaddr_out = crtc_state->active_writeback;
+
+ ret = compose_planes(&vaddr_out, primary_composer, cursor_composer);
+ if (ret) {
+ if (ret == -EINVAL && !wb_pending)
+ kfree(vaddr_out);
+ return -EINVAL;
+ }
+
+ *crc32 = compute_crc(vaddr_out, primary_composer);
+
+ if (wb_pending) {
+ drm_writeback_signal_completion(&out->wb_connector, 0);
+ spin_lock_irq(&out->composer_lock);
+ crtc_state->wb_pending = false;
+ spin_unlock_irq(&out->composer_lock);
+ } else {
+ kfree(vaddr_out);
+ }
+
+ return 0;
+}
+
/**
* vkms_composer_worker - ordered work_struct to compute CRC
*
@@ -185,12 +223,9 @@ void vkms_composer_worker(struct work_struct *work)
composer_work);
struct drm_crtc *crtc = crtc_state->base.crtc;
struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
- struct vkms_composer *primary_composer = NULL;
- struct vkms_composer *cursor_composer = NULL;
bool crc_pending, wb_pending;
- void *vaddr_out = NULL;
- u32 crc32 = 0;
u64 frame_start, frame_end;
+ u32 crc32 = 0;
int ret;

spin_lock_irq(&out->composer_lock);
@@ -210,36 +245,9 @@ void vkms_composer_worker(struct work_struct *work)
if (!crc_pending)
return;

- if (crtc_state->num_active_planes >= 1)
- primary_composer = crtc_state->active_planes[0]->composer;
-
- if (crtc_state->num_active_planes == 2)
- cursor_composer = crtc_state->active_planes[1]->composer;
-
- if (!primary_composer)
- return;
-
- if (wb_pending)
- vaddr_out = crtc_state->active_writeback;
-
- ret = compose_planes(&vaddr_out, primary_composer, cursor_composer);
- if (ret) {
- if (ret == -EINVAL && !wb_pending)
- kfree(vaddr_out);
+ ret = vkms_composer_common(crtc_state, out, crtc_state->wb_pending, &crc32);
+ if (ret == -EINVAL)
return;
- }
-
- crc32 = compute_crc(vaddr_out, primary_composer);
-
- if (wb_pending) {
- drm_writeback_signal_completion(&out->wb_connector, 0);
- spin_lock_irq(&out->composer_lock);
- crtc_state->wb_pending = false;
- spin_unlock_irq(&out->composer_lock);
- } else {
- kfree(vaddr_out);
- }
-
/*
* The worker can fall behind the vblank hrtimer, make sure we catch up.
*/
@@ -247,6 +255,20 @@ void vkms_composer_worker(struct work_struct *work)
drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32);
}

+void vkms_crtc_composer(struct vkms_crtc_state *crtc_state)
+{
+ struct drm_crtc *crtc = crtc_state->base.crtc;
+ struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
+ u32 crc32 = 0;
+ int ret;
+
+ ret = vkms_composer_common(crtc_state, out, crtc_state->wb_pending, &crc32);
+ if (ret == -EINVAL)
+ return;
+
+ drm_crtc_add_crc_entry(crtc, true, 0, &crc32);
+}
+
static const char * const pipe_crc_sources[] = {"auto"};

const char *const *vkms_get_crc_sources(struct drm_crtc *crtc,
diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index 6164349cdf11..6cc8dc23bd5d 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -224,32 +224,45 @@ static int vkms_crtc_atomic_check(struct drm_crtc *crtc,
static void vkms_crtc_atomic_enable(struct drm_crtc *crtc,
struct drm_atomic_state *state)
{
- drm_crtc_vblank_on(crtc);
+ struct vkms_device *vkmsdev = drm_device_to_vkms_device(crtc->dev);
+
+ if (!vkmsdev->config->virtual_hw)
+ drm_crtc_vblank_on(crtc);
}

static void vkms_crtc_atomic_disable(struct drm_crtc *crtc,
struct drm_atomic_state *state)
{
- drm_crtc_vblank_off(crtc);
+ struct vkms_device *vkmsdev = drm_device_to_vkms_device(crtc->dev);
+
+ if (!vkmsdev->config->virtual_hw)
+ drm_crtc_vblank_off(crtc);
}

static void vkms_crtc_atomic_begin(struct drm_crtc *crtc,
struct drm_atomic_state *state)
{
struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);
+ struct vkms_device *vkmsdev = drm_device_to_vkms_device(crtc->dev);

/* This lock is held across the atomic commit to block vblank timer
* from scheduling vkms_composer_worker until the composer is updated
*/
- spin_lock_irq(&vkms_output->lock);
+ if (!vkmsdev->config->virtual_hw)
+ spin_lock_irq(&vkms_output->lock);
}

static void vkms_crtc_atomic_flush(struct drm_crtc *crtc,
struct drm_atomic_state *state)
{
struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);
+ struct vkms_crtc_state *vkms_state = to_vkms_crtc_state(crtc->state);
+ struct vkms_device *vkmsdev = drm_device_to_vkms_device(crtc->dev);
+
+ if (vkmsdev->config->virtual_hw)
+ vkms_crtc_composer(vkms_state);

- if (crtc->state->event) {
+ if (crtc->state->event && !vkmsdev->config->virtual_hw) {
spin_lock(&crtc->dev->event_lock);

if (drm_crtc_vblank_get(crtc) != 0)
@@ -264,7 +277,8 @@ static void vkms_crtc_atomic_flush(struct drm_crtc *crtc,

vkms_output->composer_state = to_vkms_crtc_state(crtc->state);

- spin_unlock_irq(&vkms_output->lock);
+ if (!vkmsdev->config->virtual_hw)
+ spin_unlock_irq(&vkms_output->lock);
}

static const struct drm_crtc_helper_funcs vkms_crtc_helper_funcs = {
diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index 2173b82606f6..945c4495d62a 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -44,6 +44,11 @@ static bool enable_writeback = true;
module_param_named(enable_writeback, enable_writeback, bool, 0444);
MODULE_PARM_DESC(enable_writeback, "Enable/Disable writeback connector support");

+static bool enable_virtual_hw = false;
+module_param_named(enable_virtual_hw, enable_virtual_hw, bool, 0444);
+MODULE_PARM_DESC(enable_virtual_hw, "Enable/Disable virtual hardware mode(virtual \
+hardware mode disables vblank interrupts)");
+
DEFINE_DRM_GEM_FOPS(vkms_driver_fops);

static void vkms_release(struct drm_device *dev)
@@ -159,12 +164,14 @@ static int vkms_create(struct vkms_config *config)
goto out_devres;
}

- vkms_device->drm.irq_enabled = true;
+ vkms_device->drm.irq_enabled = !vkms_device->config->virtual_hw;

- ret = drm_vblank_init(&vkms_device->drm, 1);
- if (ret) {
- DRM_ERROR("Failed to vblank\n");
- goto out_devres;
+ if (!vkms_device->config->virtual_hw) {
+ ret = drm_vblank_init(&vkms_device->drm, 1);
+ if (ret) {
+ DRM_ERROR("Failed to vblank\n");
+ goto out_devres;
+ }
}

ret = vkms_modeset_init(vkms_device);
@@ -198,6 +205,7 @@ static int __init vkms_init(void)

config->cursor = enable_cursor;
config->writeback = enable_writeback;
+ config->virtual_hw = enable_virtual_hw;

return vkms_create(config);
}
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index 35540c7c4416..0730970d24bf 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -85,6 +85,7 @@ struct vkms_device;
struct vkms_config {
bool writeback;
bool cursor;
+ bool virtual_hw;
/* only set when instantiated */
struct vkms_device *dev;
};
@@ -125,8 +126,11 @@ int vkms_verify_crc_source(struct drm_crtc *crtc, const char *source_name,
size_t *values_cnt);

/* Composer Support */
+int vkms_composer_common(struct vkms_crtc_state *crtc_state, struct vkms_output *out,
+ bool wb_pending, uint32_t *crcs);
void vkms_composer_worker(struct work_struct *work);
void vkms_set_composer(struct vkms_output *out, bool enabled);
+void vkms_crtc_composer(struct vkms_crtc_state *crtc_state);

/* Writeback */
int vkms_enable_writeback_connector(struct vkms_device *vkmsdev);
--
2.25.1