When a CRTC is created, add a `writeback` file to allow to enable or
disable writeback connector support
Co-developed-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
Signed-off-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
Signed-off-by: José Expósito <jose.exposito89@xxxxxxxxx>
---
Documentation/gpu/vkms.rst | 4 +++
drivers/gpu/drm/vkms/vkms_configfs.c | 40 ++++++++++++++++++++++++++++
2 files changed, 44 insertions(+)
diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index e0699603ef53..abe7a0f5a4ab 100644
--- a/Documentation/gpu/vkms.rst
+++ b/Documentation/gpu/vkms.rst
@@ -94,6 +94,10 @@ Continue by creating one or more CRTCs::
sudo mkdir /config/vkms/my-vkms/crtcs/crtc0
+CRTCs have 1 configurable attribute:
+
+- writeback: Enable or disable writeback connector support by writing 1 or 0
+
Once you are done configuring the VKMS instance, enable it::
echo "1" | sudo tee /config/vkms/my-vkms/enabled
diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
index 1483f47244e6..233a3d4ad75c 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -74,6 +74,45 @@ struct vkms_configfs_crtc {
#define crtc_item_to_vkms_configfs_crtc(item) \
container_of(to_config_group((item)), struct vkms_configfs_crtc, group)
+static ssize_t crtc_writeback_show(struct config_item *item, char *page)
+{
+ struct vkms_configfs_crtc *crtc;
+
+ crtc = crtc_item_to_vkms_configfs_crtc(item);
+
+ guard(mutex)(&crtc->dev->lock);
+ return sprintf(page, "%d\n",
+ vkms_config_crtc_get_writeback(crtc->config));
+}
+
+static ssize_t crtc_writeback_store(struct config_item *item, const char *page,
+ size_t count)
+{
+ struct vkms_configfs_crtc *crtc;
+ bool writeback;
+
+ crtc = crtc_item_to_vkms_configfs_crtc(item);
+
+ if (kstrtobool(page, &writeback))
+ return -EINVAL;
+
+ guard(mutex)(&crtc->dev->lock);
+
+ if (crtc->dev->enabled)
+ return -EBUSY;
+
+ vkms_config_crtc_set_writeback(crtc->config, writeback);
+
+ return (ssize_t)count;
+}
+
+CONFIGFS_ATTR(crtc_, writeback);
+
+static struct configfs_attribute *crtc_item_attrs[] = {
+ &crtc_attr_writeback,
+ NULL,
+};
+
static void crtc_release(struct config_item *item)
{
struct vkms_configfs_crtc *crtc;
@@ -92,6 +131,7 @@ static struct configfs_item_operations crtc_item_operations = {
};
static const struct config_item_type crtc_item_type = {
+ .ct_attrs = crtc_item_attrs,
.ct_item_ops = &crtc_item_operations,
.ct_owner = THIS_MODULE,
};
--
2.48.1
