Re: [PATCH v2 5/6] drm/vkms: Support enabling ConfigFS devices

From: Brandon Ross Pollack
Date: Fri Aug 18 2023 - 01:26:02 EST

Next message: Brandon Ross Pollack: "Re: [PATCH v2 2/6] drm/vkms: Support multiple DRM objects (crtcs, etc.) per VKMS device"
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On 8/15/23 23:01, Marius Vlad wrote:

Hi,

See below some minor comments:

On Fri, Jun 23, 2023 at 06:23:47PM -0400, Jim Shargo wrote:

VKMS now supports creating and using virtual devices!

In addition to the enabling logic, this commit also prevents users from
adding new objects once a card is registered.

Signed-off-by: Jim Shargo <jshargo@xxxxxxxxxxxx>
---
drivers/gpu/drm/vkms/vkms_configfs.c | 37 +++--
drivers/gpu/drm/vkms/vkms_crtc.c | 4 +-
drivers/gpu/drm/vkms/vkms_drv.c | 3 +-
drivers/gpu/drm/vkms/vkms_drv.h | 2 +-
drivers/gpu/drm/vkms/vkms_output.c | 201 +++++++++++++++++++++++----
5 files changed, 202 insertions(+), 45 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
index 544024735d19..f5eed6d23dcd 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -504,29 +504,40 @@ static ssize_t device_enabled_store(struct config_item *item, const char *buf,
{
struct vkms_configfs *configfs = item_to_configfs(item);
struct vkms_device *device;
- int value, ret;
+ int enabled, ret;
- ret = kstrtoint(buf, 0, &value);
+ ret = kstrtoint(buf, 0, &enabled);
if (ret)
return ret;
- if (value != 1)
- return -EINVAL;
-
- mutex_lock(&configfs->lock);
-
- if (configfs->vkms_device) {
+ if (enabled == 0) {
+ mutex_lock(&configfs->lock);
+ if (configfs->vkms_device) {
+ vkms_remove_device(configfs->vkms_device);
+ configfs->vkms_device = NULL;
+ }
mutex_unlock(&configfs->lock);
+
return len;
}
- device = vkms_add_device(configfs);
- mutex_unlock(&configfs->lock);
+ if (enabled == 1) {
+ mutex_lock(&configfs->lock);
+ if (!configfs->vkms_device) {
+ device = vkms_add_device(configfs);
+ if (IS_ERR(device)) {
+ mutex_unlock(&configfs->lock);
+ return -PTR_ERR(device);
+ }
+
+ configfs->vkms_device = device;
+ }
+ mutex_unlock(&configfs->lock);
- if (IS_ERR(device))
- return -PTR_ERR(device);
+ return len;
+ }
- return len;
+ return -EINVAL;
}
CONFIGFS_ATTR(device_, enabled);
diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index d91e49c53adc..5ebb5264f6ef 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -278,7 +278,7 @@ static const struct drm_crtc_helper_funcs vkms_crtc_helper_funcs = {
struct vkms_crtc *vkms_crtc_init(struct vkms_device *vkmsdev,
struct drm_plane *primary,
- struct drm_plane *cursor)
+ struct drm_plane *cursor, const char *name)
{
struct drm_device *dev = &vkmsdev->drm;
struct vkms_crtc *vkms_crtc;
@@ -290,7 +290,7 @@ struct vkms_crtc *vkms_crtc_init(struct vkms_device *vkmsdev,
vkms_crtc = &vkmsdev->output.crtcs[vkmsdev->output.num_crtcs++];
ret = drmm_crtc_init_with_planes(dev, &vkms_crtc->base, primary, cursor,
- &vkms_crtc_funcs, NULL);
+ &vkms_crtc_funcs, name);
if (ret) {
DRM_ERROR("Failed to init CRTC\n");
goto out_error;
diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index 1b5b7143792f..314a04659c5f 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -210,7 +210,7 @@ static int vkms_platform_probe(struct platform_device *pdev)
ret = drm_dev_register(&vkms_device->drm, 0);
if (ret) {
DRM_ERROR("Unable to register device with id %d\n", pdev->id);
- return ret;
+ goto out_release_group;
}
drm_fbdev_generic_setup(&vkms_device->drm, 0);
@@ -256,6 +256,7 @@ struct vkms_device *vkms_add_device(struct vkms_configfs *configfs)
dev, &vkms_platform_driver.driver))) {
pdev = to_platform_device(dev);
max_id = max(max_id, pdev->id);
+ put_device(dev);
}
pdev = platform_device_register_data(NULL, DRIVER_NAME, max_id + 1,
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index 3634eeeb4548..3d592d085f49 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -239,7 +239,7 @@ void vkms_remove_device(struct vkms_device *vkms_device);
/* CRTC */
struct vkms_crtc *vkms_crtc_init(struct vkms_device *vkmsdev,
struct drm_plane *primary,
- struct drm_plane *cursor);
+ struct drm_plane *cursor, const char *name);
int vkms_output_init(struct vkms_device *vkmsdev);
int vkms_output_init_default(struct vkms_device *vkmsdev);
diff --git a/drivers/gpu/drm/vkms/vkms_output.c b/drivers/gpu/drm/vkms/vkms_output.c
index c9e6c653de19..806ff01954ad 100644
--- a/drivers/gpu/drm/vkms/vkms_output.c
+++ b/drivers/gpu/drm/vkms/vkms_output.c
@@ -2,8 +2,10 @@
#include <drm/drm_atomic_helper.h>
#include <drm/drm_connector.h>
+#include <drm/drm_crtc.h>
#include <drm/drm_edid.h>
#include <drm/drm_encoder.h>
+#include <drm/drm_plane.h>
#include <drm/drm_probe_helper.h>
#include <drm/drm_simple_kms_helper.h>
@@ -82,7 +84,6 @@ static struct drm_encoder *vkms_encoder_init(struct vkms_device *vkms_device)
int vkms_output_init_default(struct vkms_device *vkmsdev)
{
- struct vkms_output *output = &vkmsdev->output;
struct drm_device *dev = &vkmsdev->drm;
struct drm_connector *connector;
struct drm_encoder *encoder;
@@ -101,8 +102,7 @@ int vkms_output_init_default(struct vkms_device *vkmsdev)
struct vkms_plane *overlay = vkms_plane_init(
vkmsdev, DRM_PLANE_TYPE_OVERLAY);
if (IS_ERR(overlay)) {
- ret = PTR_ERR(overlay);
- goto err_planes;
+ return PTR_ERR(overlay);
}
}
}
@@ -110,17 +110,16 @@ int vkms_output_init_default(struct vkms_device *vkmsdev)
if (vkmsdev->config.cursor) {
cursor = vkms_plane_init(vkmsdev, DRM_PLANE_TYPE_CURSOR);
if (IS_ERR(cursor)) {
- ret = PTR_ERR(cursor);
- goto err_planes;
+ return PTR_ERR(cursor);
}
}
vkms_crtc = vkms_crtc_init(vkmsdev, &primary->base,
- cursor ? &cursor->base : NULL);
+ cursor ? &cursor->base : NULL,
+ "crtc-default");
if (IS_ERR(vkms_crtc)) {
DRM_ERROR("Failed to init crtc\n");
- ret = PTR_ERR(vkms_crtc);
- goto err_planes;
+ return PTR_ERR(vkms_crtc);
}
for (int i = 0; i < vkmsdev->output.num_planes; i++) {
@@ -131,22 +130,20 @@ int vkms_output_init_default(struct vkms_device *vkmsdev)
connector = vkms_connector_init(vkmsdev);
if (IS_ERR(connector)) {
DRM_ERROR("Failed to init connector\n");
- ret = PTR_ERR(connector);
- goto err_connector;
+ return PTR_ERR(connector);
}
encoder = vkms_encoder_init(vkmsdev);
if (IS_ERR(encoder)) {
DRM_ERROR("Failed to init encoder\n");
- ret = PTR_ERR(encoder);
- goto err_encoder;
+ return PTR_ERR(encoder);
}
encoder->possible_crtcs |= drm_crtc_mask(&vkms_crtc->base);
ret = drm_connector_attach_encoder(connector, encoder);
if (ret) {
DRM_ERROR("Failed to attach connector to encoder\n");
- goto err_attach;
+ return ret;
}
if (vkmsdev->config.writeback) {
@@ -158,27 +155,175 @@ int vkms_output_init_default(struct vkms_device *vkmsdev)
drm_mode_config_reset(dev);
return 0;
+}
-err_attach:
- drm_encoder_cleanup(encoder);
+static bool is_object_linked(struct vkms_config_links *links, unsigned long idx)
+{
+ return links->linked_object_bitmap & (1 << idx);
+}
-err_encoder:
- drm_connector_cleanup(connector);
+int vkms_output_init(struct vkms_device *vkmsdev)
+{
+ struct drm_device *dev = &vkmsdev->drm;
+ struct vkms_configfs *configfs = vkmsdev->configfs;
+ struct vkms_output *output = &vkmsdev->output;
+ struct plane_map {
+ struct vkms_config_plane *config_plane;
+ struct vkms_plane *plane;
+ } plane_map[VKMS_MAX_PLANES] = { 0 };
+ struct encoder_map {
+ struct vkms_config_encoder *config_encoder;
+ struct drm_encoder *encoder;
+ } encoder_map[VKMS_MAX_OUTPUT_OBJECTS] = { 0 };
+ struct config_item *item;
+ int map_idx = 0;
+
+ list_for_each_entry(item, &configfs->planes_group.cg_children,
+ ci_entry) {
+ struct vkms_config_plane *config_plane =
+ item_to_config_plane(item);
+ struct vkms_plane *plane =
+ vkms_plane_init(vkmsdev, config_plane->type);
+
+ if (IS_ERR(plane)) {
+ DRM_ERROR("Unable to init plane from config: %s",
+ item->ci_name);
+ return PTR_ERR(plane);
+ }
-err_connector:
- drm_crtc_cleanup(&vkms_crtc->base);
+ plane_map[map_idx].config_plane = config_plane;
+ plane_map[map_idx].plane = plane;
+ map_idx += 1;
+ }
-err_planes:
- for (int i = 0; i < output->num_planes; i++) {
- drm_plane_cleanup(&output->planes[i].base);
+ map_idx = 0;
+ list_for_each_entry(item, &configfs->encoders_group.cg_children,
+ ci_entry) {
+ struct vkms_config_encoder *config_encoder =
+ item_to_config_encoder(item);
+ struct drm_encoder *encoder = vkms_encoder_init(vkmsdev);
+
+ if (IS_ERR(encoder)) {
+ DRM_ERROR("Failed to init config encoder: %s",
+ item->ci_name);
+ return PTR_ERR(encoder);
+ }
+ encoder_map[map_idx].config_encoder = config_encoder;

A two connector configuration without an encoder would have the
potential of blowing up if we don't create a second_encoder.

What a catch!!! I tested this and sure enough BOOM!

Switched to limiting based on output->num_encoders as it should be.

+ encoder_map[map_idx].encoder = encoder;
+ map_idx += 1;
}
- memset(output, 0, sizeof(*output));
+ list_for_each_entry(item, &configfs->connectors_group.cg_children,
+ ci_entry) {
+ struct vkms_config_connector *config_connector =
+ item_to_config_connector(item);
+ struct drm_connector *connector = vkms_connector_init(vkmsdev);
- return ret;
-}
+ if (IS_ERR(connector)) {
+ DRM_ERROR("Failed to init connector from config: %s",
+ item->ci_name);
+ return PTR_ERR(connector);
+ }
-int vkms_output_init(struct vkms_device *vkmsdev)
-{
- return -ENOTSUPP;
+ for (int j = 0; j < output->num_connectors; j++) {
+ struct encoder_map *encoder = &encoder_map[j];
+
+ if (is_object_linked(
+ &config_connector->possible_encoders,
+ encoder->config_encoder
+ ->encoder_config_idx)) {

Here encoder->config_encoder for two connectors but a single encoder
will give back a empty encoder.

+ drm_connector_attach_encoder(connector,
+ encoder->encoder);
+ }
+ }
+ }
+
+ list_for_each_entry(item, &configfs->crtcs_group.cg_children,
+ ci_entry) {
+ struct vkms_config_crtc *config_crtc =
+ item_to_config_crtc(item);
+ struct vkms_crtc *vkms_crtc;
+ struct drm_plane *primary = NULL, *cursor = NULL;
+
+ for (int j = 0; j < output->num_planes; j++) {
+ struct plane_map *plane_entry = &plane_map[j];
+ struct drm_plane *plane = &plane_entry->plane->base;
+
+ if (!is_object_linked(
+ &plane_entry->config_plane->possible_crtcs,
+ config_crtc->crtc_config_idx)) {
+ continue;
+ }
+
+ if (plane->type == DRM_PLANE_TYPE_PRIMARY) {
+ if (primary) {
+ DRM_WARN(
+ "Too many primary planes found for crtc %s.",
+ item->ci_name);
+ return EINVAL;
+ }
+ primary = plane;
+ } else if (plane->type == DRM_PLANE_TYPE_CURSOR) {
+ if (cursor) {
+ DRM_WARN(
+ "Too many cursor planes found for crtc %s.",
+ item->ci_name);
+ return EINVAL;
+ }
+ cursor = plane;
+ }
+ }
+
+ if (!primary) {
+ DRM_WARN("No primary plane configured for crtc %s",
+ item->ci_name);
+ return EINVAL;
+ }
+
+ vkms_crtc =
+ vkms_crtc_init(vkmsdev, primary, cursor, item->ci_name);
+ if (IS_ERR(vkms_crtc)) {
+ DRM_WARN("Unable to init crtc from config: %s",
+ item->ci_name);
+ return PTR_ERR(vkms_crtc);
+ }
+
+ for (int j = 0; j < output->num_planes; j++) {
+ struct plane_map *plane_entry = &plane_map[j];
+
+ if (!plane_entry->plane)
+ break;
+
+ if (is_object_linked(
+ &plane_entry->config_plane->possible_crtcs,
+ config_crtc->crtc_config_idx)) {
+ plane_entry->plane->base.possible_crtcs |=
+ drm_crtc_mask(&vkms_crtc->base);
+ }
+ }
+
+ for (int j = 0; j < output->num_encoders; j++) {
+ struct encoder_map *encoder_entry = &encoder_map[j];
+
+ if (is_object_linked(&encoder_entry->config_encoder
+ ->possible_crtcs,
+ config_crtc->crtc_config_idx)) {
+ encoder_entry->encoder->possible_crtcs |=
+ drm_crtc_mask(&vkms_crtc->base);
+ }
+ }
+
+ if (vkmsdev->config.writeback) {
+ int ret = vkms_enable_writeback_connector(vkmsdev,
+ vkms_crtc);
+ if (ret)
+ DRM_WARN(
+ "Failed to init writeback connector for config crtc: %s. Error code %d",
+ item->ci_name, ret);
+ }
+ }

I think we might be needing here a test for missing symlinks - invalid
configurations, like unused crtcs, encoders, connectors. I
suppose anything that's not matched with is_object_linked(),
such we avoid invalid configuration found by drm_mode_config_validate()
and inform users about missing them.

An example here would be to create a second encoder, connector, crtc and
not symlink them to their possible_encoders,possible_crtcs mask. An
i-g-t test for this very thing would be needed to stress different kind
of combinations.

I wonder about this. Shouldn't a user be free to create dangling files to simulate some scenario?

I could see a further development to publish a warning in the log, but disallowing it seems overly restrictive.

Either way we could accomplish this pretty easily by adding a flag to each vkms object in the form of `bool is_linked` and set it when we detect it's linked. Then at the end iterate through all planes, encoders, connectors, crtcs that can be linked and if they are not just publish a warning saying

kwarn: "crtc/plane/encoder $NAME is created but unlinked"

IGT tests to test that that was done make sense to me.

+
+ drm_mode_config_reset(dev);
+
+ return 0;
}
--
2.41.0.162.gfafddb0af9-goog

Next message: Brandon Ross Pollack: "Re: [PATCH v2 2/6] drm/vkms: Support multiple DRM objects (crtcs, etc.) per VKMS device"
Previous message: pr-tracker-bot: "Re: [GIT PULL] Networking for v6.5-rc7"
Next in thread: Marius Vlad: "Re: [PATCH v2 5/6] drm/vkms: Support enabling ConfigFS devices"
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