Hi Marius,

On 5/8/23 04:53, Marius Vlad wrote:
This adds support for creating multiple virtual pipes, in case one would
need to display multiple independent things on different outputs.

We use a module parameter to specify how many to create,  defaulting to
just one with the possibility of specifying a maximum of 4 possible pipes.

This is of particular importance when testing out the DRM back-end in
compositors, but also to be able to independently set different DPMS states.

Signed-off-by: Marius Vlad <marius.v...@collabora.com>
---
  drivers/gpu/drm/vkms/vkms_crtc.c      |  3 +--
  drivers/gpu/drm/vkms/vkms_drv.c       | 37 ++++++++++++++++++++++-----
  drivers/gpu/drm/vkms/vkms_drv.h       | 12 ++++++---
  drivers/gpu/drm/vkms/vkms_output.c    |  5 ++--
  drivers/gpu/drm/vkms/vkms_writeback.c | 24 ++++++++---------
  5 files changed, 55 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index 515f6772b866..051e7b647db9 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -89,8 +89,7 @@ static bool vkms_get_vblank_timestamp(struct drm_crtc *crtc,
  {
        struct drm_device *dev = crtc->dev;
        unsigned int pipe = crtc->index;
-       struct vkms_device *vkmsdev = drm_device_to_vkms_device(dev);
-       struct vkms_output *output = &vkmsdev->output;
+       struct vkms_output *output = drm_crtc_to_vkms_output(crtc);
        struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
if (!READ_ONCE(vblank->enabled)) {
diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index bd53194f1525..b93157fa5336 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -51,14 +51,19 @@ static bool enable_overlay;
  module_param_named(enable_overlay, enable_overlay, bool, 0444);
  MODULE_PARM_DESC(enable_overlay, "Enable/Disable overlay support");
+static unsigned int max_pipes = 1;
+module_param_named(max_pipes, max_pipes, int, 0444);
+MODULE_PARM_DESC(max_pipes, "Specify how many pipes to create");
+
  DEFINE_DRM_GEM_FOPS(vkms_driver_fops);
static void vkms_release(struct drm_device *dev)
  {
-       struct vkms_device *vkms = drm_device_to_vkms_device(dev);
+       int i;
+       struct vkms_device *vkmsdev = drm_device_to_vkms_device(dev);
- if (vkms->output.composer_workq)
-               destroy_workqueue(vkms->output.composer_workq);
+       for (i = 0; i < vkmsdev->config->max_pipes; i++)
+               destroy_workqueue(vkmsdev->output[i].composer_workq);
  }
static void vkms_atomic_commit_tail(struct drm_atomic_state *old_state)
@@ -100,6 +105,7 @@ static int vkms_config_show(struct seq_file *m, void *data)
        seq_printf(m, "cursor=%d\n", vkmsdev->config->cursor);
        seq_printf(m, "overlay=%d\n", vkmsdev->config->overlay);
        seq_printf(m, "overlay_planes=%d\n", vkmsdev->config->overlay_planes);
+       seq_printf(m, "pipes=%d\n", vkmsdev->config->max_pipes);
return 0;
  }
@@ -134,7 +140,7 @@ static const struct drm_mode_config_helper_funcs 
vkms_mode_config_helpers = {
  static int vkms_modeset_init(struct vkms_device *vkmsdev)
  {
        struct drm_device *dev = &vkmsdev->drm;
-       int ret;
+       int ret, i;
ret = drmm_mode_config_init(dev);
        if (ret)
@@ -153,7 +159,14 @@ static int vkms_modeset_init(struct vkms_device *vkmsdev)
        dev->mode_config.preferred_depth = 0;
        dev->mode_config.helper_private = &vkms_mode_config_helpers;
- return vkms_output_init(vkmsdev, 0);
+       for (i = 0; i < vkmsdev->config->max_pipes; i++) {
+               ret = vkms_output_init(vkmsdev, i);
+               if (ret)
+                       return ret;
+       }
+
+       drm_mode_config_reset(dev);
+       return ret;
  }
static int vkms_create(struct vkms_config *config)
@@ -189,7 +202,7 @@ static int vkms_create(struct vkms_config *config)
                goto out_devres;
        }
- ret = drm_vblank_init(&vkms_device->drm, 1);
+       ret = drm_vblank_init(&vkms_device->drm, config->max_pipes);
        if (ret) {
                DRM_ERROR("Failed to vblank\n");
                goto out_devres;
@@ -232,7 +245,19 @@ static int __init vkms_init(void)
        config->writeback = enable_writeback;
        config->overlay = enable_overlay;
        config->overlay_planes = NUM_OVERLAY_PLANES;
+       config->max_pipes = max_pipes;
+
+       if (config->max_pipes > NUM_MAX_PIPES)
+               config->max_pipes = NUM_MAX_PIPES;
+       if (config->max_pipes < NUM_MIN_PIPES)
+               config->max_pipes = NUM_MIN_PIPES;
+
+       /* with NUM_OVERLAY_PLANES overlays and 4 pipes we'll exceed the amount
+        * of planes we can have; see drm_mode_config::num_total_plane */
+       if (config->overlay && config->max_pipes == NUM_MAX_PIPES)
+               config->overlay_planes -= 2;

I'm not sure if you really need to set the overlay planes as a kernel parameter.
You could just reduce NUM_OVERLAY_PLANES to 6 or even 4. This way you could
remove this if statement and make the logic more simple.

Best Regards,
- Maíra Canal

+ DRM_INFO("Initialized with %u pipes\n", config->max_pipes);
        ret = vkms_create(config);
        if (ret)
                kfree(config);
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index ae2b38360236..29617cd491e3 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -21,7 +21,9 @@
  #define XRES_MAX  8192
  #define YRES_MAX  8192
-#define NUM_OVERLAY_PLANES 8
+#define NUM_OVERLAY_PLANES     8
+#define NUM_MAX_PIPES          4
+#define NUM_MIN_PIPES          1
struct vkms_frame_info {
        struct drm_framebuffer *fb;
@@ -113,6 +115,7 @@ struct vkms_config {
        bool cursor;
        bool overlay;
        unsigned int overlay_planes;
+       unsigned int max_pipes;
        /* only set when instantiated */
        struct vkms_device *dev;
  };
@@ -120,13 +123,16 @@ struct vkms_config {
  struct vkms_device {
        struct drm_device drm;
        struct platform_device *platform;
-       struct vkms_output output;
+       struct vkms_output output[NUM_MAX_PIPES];
        const struct vkms_config *config;
  };
#define drm_crtc_to_vkms_output(target) \
        container_of(target, struct vkms_output, crtc)
+#define wb_connector_to_vkms_output(target) \
+       container_of(target, struct vkms_output, wb_connector)
+
  #define drm_device_to_vkms_device(target) \
        container_of(target, struct vkms_device, drm)
@@ -158,6 +164,6 @@ void vkms_set_composer(struct vkms_output *out, bool enabled);
  void vkms_compose_row(struct line_buffer *stage_buffer, struct 
vkms_plane_state *plane, int y);
/* Writeback */
-int vkms_enable_writeback_connector(struct vkms_device *vkmsdev);
+int vkms_enable_writeback_connector(struct vkms_device *vkmsdev, int index);
#endif /* _VKMS_DRV_H_ */
diff --git a/drivers/gpu/drm/vkms/vkms_output.c 
b/drivers/gpu/drm/vkms/vkms_output.c
index f4e67a0ad712..ca4dc16b8d01 100644
--- a/drivers/gpu/drm/vkms/vkms_output.c
+++ b/drivers/gpu/drm/vkms/vkms_output.c
@@ -48,7 +48,7 @@ static int vkms_add_overlay_plane(struct vkms_device 
*vkmsdev, int index,
int vkms_output_init(struct vkms_device *vkmsdev, int index)
  {
-       struct vkms_output *output = &vkmsdev->output;
+       struct vkms_output *output = &vkmsdev->output[index];
        struct drm_device *dev = &vkmsdev->drm;
        struct drm_connector *connector = &output->connector;
        struct drm_encoder *encoder = &output->encoder;
@@ -104,12 +104,11 @@ int vkms_output_init(struct vkms_device *vkmsdev, int 
index)
        }
if (vkmsdev->config->writeback) {
-               writeback = vkms_enable_writeback_connector(vkmsdev);
+               writeback = vkms_enable_writeback_connector(vkmsdev, index);
                if (writeback)
                        DRM_ERROR("Failed to init writeback connector\n");
        }
- drm_mode_config_reset(dev); return 0; diff --git a/drivers/gpu/drm/vkms/vkms_writeback.c b/drivers/gpu/drm/vkms/vkms_writeback.c
index 84a51cd281b9..5f291689f870 100644
--- a/drivers/gpu/drm/vkms/vkms_writeback.c
+++ b/drivers/gpu/drm/vkms/vkms_writeback.c
@@ -101,7 +101,7 @@ static void vkms_wb_cleanup_job(struct 
drm_writeback_connector *connector,
                                struct drm_writeback_job *job)
  {
        struct vkms_writeback_job *vkmsjob = job->priv;
-       struct vkms_device *vkmsdev;
+       struct vkms_output *output = wb_connector_to_vkms_output(connector);
if (!job->fb)
                return;
@@ -110,19 +110,18 @@ static void vkms_wb_cleanup_job(struct 
drm_writeback_connector *connector,
drm_framebuffer_put(vkmsjob->wb_frame_info.fb); - vkmsdev = drm_device_to_vkms_device(job->fb->dev);
-       vkms_set_composer(&vkmsdev->output, false);
+       vkms_set_composer(output, false);
        kfree(vkmsjob);
  }
static void vkms_wb_atomic_commit(struct drm_connector *conn,
                                  struct drm_atomic_state *state)
  {
-       struct drm_connector_state *connector_state = 
drm_atomic_get_new_connector_state(state,
-                                                                               
         conn);
-       struct vkms_device *vkmsdev = drm_device_to_vkms_device(conn->dev);
-       struct vkms_output *output = &vkmsdev->output;
-       struct drm_writeback_connector *wb_conn = &output->wb_connector;
+       struct drm_connector_state *connector_state =
+               drm_atomic_get_new_connector_state(state, conn);
+       struct drm_writeback_job *wb_job = connector_state->writeback_job;
+       struct drm_writeback_connector *wb_conn = wb_job->connector;
+       struct vkms_output *output = wb_connector_to_vkms_output(wb_conn);
        struct drm_connector_state *conn_state = wb_conn->base.state;
        struct vkms_crtc_state *crtc_state = output->composer_state;
        struct drm_framebuffer *fb = connector_state->writeback_job->fb;
@@ -135,7 +134,7 @@ static void vkms_wb_atomic_commit(struct drm_connector 
*conn,
        if (!conn_state)
                return;
- vkms_set_composer(&vkmsdev->output, true);
+       vkms_set_composer(output, true);
active_wb = conn_state->writeback_job->priv;
        wb_frame_info = &active_wb->wb_frame_info;
@@ -147,6 +146,7 @@ static void vkms_wb_atomic_commit(struct drm_connector 
*conn,
        wb_frame_info->cpp = fb->format->cpp[0];
        crtc_state->wb_pending = true;
        spin_unlock_irq(&output->composer_lock);
+
        drm_writeback_queue_job(wb_conn, connector_state);
        active_wb->wb_write = get_line_to_frame_function(wb_format);
        drm_rect_init(&wb_frame_info->src, 0, 0, crtc_width, crtc_height);
@@ -160,9 +160,9 @@ static const struct drm_connector_helper_funcs 
vkms_wb_conn_helper_funcs = {
        .atomic_commit = vkms_wb_atomic_commit,
  };
-int vkms_enable_writeback_connector(struct vkms_device *vkmsdev)
+int vkms_enable_writeback_connector(struct vkms_device *vkmsdev, int index)
  {
-       struct drm_writeback_connector *wb = &vkmsdev->output.wb_connector;
+       struct drm_writeback_connector *wb = 
&vkmsdev->output[index].wb_connector;
drm_connector_helper_add(&wb->base, &vkms_wb_conn_helper_funcs); @@ -171,5 +171,5 @@ int vkms_enable_writeback_connector(struct vkms_device *vkmsdev)
                                            &vkms_wb_encoder_helper_funcs,
                                            vkms_wb_formats,
                                            ARRAY_SIZE(vkms_wb_formats),
-                                           1);
+                                           1 << index);
  }

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