On 18/02/25 - 18:07, José Expósito wrote:
> 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@bootlin.com>
> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
> Signed-off-by: José Expósito <jose.exposito89@gmail.com>
> ---
> Documentation/gpu/vkms.rst | 4 +++
> drivers/gpu/drm/vkms/vkms_configfs.c | 47 ++++++++++++++++++++++++++++
> 2 files changed, 51 insertions(+)
>
> diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
> index da5157adfd79..4e87d8a81844 100644
> --- a/Documentation/gpu/vkms.rst
> +++ b/Documentation/gpu/vkms.rst
> @@ -93,6 +93,10 @@ 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
Can we add: "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 52205a8a9cb4..88037a57a138 100644
> --- a/drivers/gpu/drm/vkms/vkms_configfs.c
> +++ b/drivers/gpu/drm/vkms/vkms_configfs.c
> @@ -73,6 +73,52 @@ 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;
> + bool writeback;
> +
> + crtc = crtc_item_to_vkms_configfs_crtc(item);
> +
> + mutex_lock(&crtc->dev->lock);
> + writeback = vkms_config_crtc_get_writeback(crtc->config);
> + mutex_unlock(&crtc->dev->lock);
> +
> + return sprintf(page, "%d\n", writeback);
> +}
> +
> +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;
> +
> + mutex_lock(&crtc->dev->lock);
> +
> + if (crtc->dev->enabled) {
> + mutex_unlock(&crtc->dev->lock);
> + return -EPERM;
> + }
> +
> + vkms_config_crtc_set_writeback(crtc->config, writeback);
> +
> + mutex_unlock(&crtc->dev->lock);
> +
> + 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 +138,7 @@ 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
>