[PATCH RFC] drm: Add a new connector atomic property for link status
Daniel Vetter
daniel at ffwll.ch
Wed Nov 23 10:00:59 UTC 2016
On Tue, Nov 22, 2016 at 05:30:21PM -0800, Manasi Navare wrote:
> This is RFC patch for adding a connector link-status property
> and making it atomic by adding it to the drm_connector_state.
> This is to make sure its wired properly in drm_atomic_connector_set_property
> and drm_atomic_connector_get_property functions.
>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Cc: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
> ---
> drivers/gpu/drm/drm_atomic.c | 5 ++++
> drivers/gpu/drm/drm_connector.c | 65 +++++++++++++++++++++++++++++++++++++++--
> include/drm/drm_connector.h | 12 +++++++-
> include/drm/drm_mode_config.h | 5 ++++
> include/uapi/drm/drm_mode.h | 4 +++
> 5 files changed, 88 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 89737e4..644d19f 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -1087,6 +1087,9 @@ int drm_atomic_connector_set_property(struct drm_connector *connector,
> * now?) atomic writes to DPMS property:
> */
> return -EINVAL;
> + } else if (property == config->link_status_property) {
> + state->link_status = val;
> + return 0;
> } else if (connector->funcs->atomic_set_property) {
> return connector->funcs->atomic_set_property(connector,
> state, property, val);
> @@ -1135,6 +1138,8 @@ static void drm_atomic_connector_print_state(struct drm_printer *p,
> *val = (state->crtc) ? state->crtc->base.id : 0;
> } else if (property == config->dpms_property) {
> *val = connector->dpms;
> + } else if (property == config->link_status_property) {
> + *val = state->link_status;
> } else if (connector->funcs->atomic_get_property) {
> return connector->funcs->atomic_get_property(connector,
> state, property, val);
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index 5a45262..4576c9f 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -243,6 +243,10 @@ int drm_connector_init(struct drm_device *dev,
> drm_object_attach_property(&connector->base,
> config->dpms_property, 0);
>
> + drm_object_attach_property(&connector->base,
> + config->link_status_property,
> + 0);
> +
> if (drm_core_check_feature(dev, DRIVER_ATOMIC)) {
> drm_object_attach_property(&connector->base, config->prop_crtc_id, 0);
> }
> @@ -506,6 +510,12 @@ const char *drm_get_subpixel_order_name(enum subpixel_order order)
> };
> DRM_ENUM_NAME_FN(drm_get_dpms_name, drm_dpms_enum_list)
>
> +static const struct drm_prop_enum_list drm_link_status_enum_list[] = {
> + { DRM_MODE_LINK_STATUS_GOOD, "Good" },
> + { DRM_MODE_LINK_STATUS_BAD, "Bad" },
> +};
> +DRM_ENUM_NAME_FN(drm_get_link_status_name, drm_link_status_enum_list)
> +
> /**
> * drm_display_info_set_bus_formats - set the supported bus formats
> * @info: display info to store bus formats in
> @@ -616,7 +626,7 @@ int drm_display_info_set_bus_formats(struct drm_display_info *info,
> * path property the MST manager created. Userspace cannot change this
> * property.
> * TILE:
> - * Connector tile group property to indicate how a set of DRM connector
> + * Connector tile group property to indicate how a set of DRM connector
> * compose together into one logical screen. This is used by both high-res
> * external screens (often only using a single cable, but exposing multiple
> * DP MST sinks), or high-res integrated panels (like dual-link DSI) which
> @@ -625,7 +635,14 @@ int drm_display_info_set_bus_formats(struct drm_display_info *info,
> * tiling and virtualize both &drm_crtc and &drm_plane if needed. Drivers
> * should update this value using drm_mode_connector_set_tile_property().
> * Userspace cannot change this property.
> - *
> + * link-status:
> + * Connector link-status property to indicate the status of link during
> + * the modeset. The default value of link-status is "GOOD". If something
> + * fails during modeset, the kernel driver can set this to "BAD", prune
> + * the mode list based on new link parameters and send a hotplug uevent
> + * to notify userspace to re-check the valid modes through GET_CONNECTOR
> + * IOCTL and redo a modeset. Drivers should update this value using
> + * drm_mode_connector_set_link_status_property().
> * Connectors also have one standardized atomic property:
> *
> * CRTC_ID:
> @@ -666,6 +683,13 @@ int drm_connector_create_standard_properties(struct drm_device *dev)
> return -ENOMEM;
> dev->mode_config.tile_property = prop;
>
> + prop = drm_property_create_enum(dev, DRM_MODE_PROP_ATOMIC, "link-status",
> + drm_link_status_enum_list,
> + ARRAY_SIZE(drm_link_status_enum_list));
> + if (!prop)
> + return -ENOMEM;
> + dev->mode_config.link_status_property = prop;
> +
> return 0;
> }
>
> @@ -995,6 +1019,43 @@ int drm_mode_connector_update_edid_property(struct drm_connector *connector,
> }
> EXPORT_SYMBOL(drm_mode_connector_update_edid_property);
>
> +/**
> + * drm_mode_connector_set_link_status_property - Set link status property of a connector
> + * @connector: drm connector
> + * @link_status: new value of link status property (0: Good, 1: Bad)
> + *
> + * In usual working scenario, this link status property will always be set to
> + * "GOOD". If something fails during or after a mode set, the kernel driver should
> + * set this link status property to "BAD" and prune the mode list based on new
> + * information. The caller then needs to send a hotplug uevent for userspace to
> + * re-check the valid modes through GET_CONNECTOR_IOCTL and retry modeset.
> + *
> + * Note that a lot of existing userspace do not handle this property.
> + * Drivers can therefore not rely on userspace to fix up everything and
> + * should try to handle issues (like just re-training a link) without
> + * userspace's intervention. This should only be used when the current mode
> + * fails and userspace must select a different display mode.
> + * The DRM driver can chose to not modify property and keep link status
> + * as "GOOD" always to keep the user experience same as it currently is.
> + *
> + * The reason for adding this property is to handle link training failures, but
> + * it is not limited to DP or link training. For example, if we implement
> + * asynchronous setcrtc, this property can be used to report any failures in that.
> + */
> +void drm_mode_connector_set_link_status_property(struct drm_connector *connector,
> + uint64_t link_status)
> +{
> + struct drm_device *dev = connector->dev;
> +
> + /* Make sure the mutex is grabbed */
> + lockdep_assert_held(&dev->mode_config.mutex);
For atomic the lock we need is dev->mode_config.connection_mutex); Maybe
we should just grab that here, from a quick check it shouldn't result in a
deadlock.
> + connector->link_status = link_status;
You need to set connector->state->link_status here for an atomic property.
> + drm_object_property_set_value(&connector->base,
> + dev->mode_config.link_status_property,
> + link_status);
And this here isn't needed anymore with atomic.
> +}
> +EXPORT_SYMBOL(drm_mode_connector_set_link_status_property);
> +
> int drm_mode_connector_set_obj_prop(struct drm_mode_object *obj,
> struct drm_property *property,
> uint64_t value)
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index 34f9741..3d513ab 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -213,6 +213,9 @@ struct drm_connector_state {
>
> struct drm_encoder *best_encoder;
>
> + /* Connector Link status */
> + unsigned int link_status;
enum drm_link_status {
DRM_LINK_STATUS_GOOD = DRM_MODE_LINK_STATUS_GOOD;
DRM_LINK_STATUS_BAD = DRM_MODE_LINK_STATUS_GOOD;
};
This way you don't need a comment explaing that 0 is good and 1 is bad.
> +
> struct drm_atomic_state *state;
> };
>
> @@ -695,6 +698,12 @@ struct drm_connector {
> uint8_t num_h_tile, num_v_tile;
> uint8_t tile_h_loc, tile_v_loc;
> uint16_t tile_h_size, tile_v_size;
> +
> + /* Connector Link status
> + * 0: If the link is Good
> + * 1: If the link is Bad
> + */
> + int link_status;
This one needs to go, we don't want to duplicate this information.
> };
>
> #define obj_to_connector(x) container_of(x, struct drm_connector, base)
> @@ -767,12 +776,13 @@ int drm_mode_create_tv_properties(struct drm_device *dev,
> int drm_mode_create_scaling_mode_property(struct drm_device *dev);
> int drm_mode_create_aspect_ratio_property(struct drm_device *dev);
> int drm_mode_create_suggested_offset_properties(struct drm_device *dev);
> -
> int drm_mode_connector_set_path_property(struct drm_connector *connector,
> const char *path);
> int drm_mode_connector_set_tile_property(struct drm_connector *connector);
> int drm_mode_connector_update_edid_property(struct drm_connector *connector,
> const struct edid *edid);
> +void drm_mode_connector_set_link_status_property(struct drm_connector *connector,
> + uint64_t link_status);
>
> /**
> * struct drm_tile_group - Tile group metadata
> diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
> index bf9991b..86faee4 100644
> --- a/include/drm/drm_mode_config.h
> +++ b/include/drm/drm_mode_config.h
> @@ -431,6 +431,11 @@ struct drm_mode_config {
> */
> struct drm_property *tile_property;
> /**
> + * @link_status_property: Default connector property for link status
> + * of a connector
> + */
> + struct drm_property *link_status_property;
> + /**
> * @plane_type_property: Default plane property to differentiate
> * CURSOR, PRIMARY and OVERLAY legacy uses of planes.
> */
> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> index 728790b..309c478 100644
> --- a/include/uapi/drm/drm_mode.h
> +++ b/include/uapi/drm/drm_mode.h
> @@ -123,6 +123,10 @@
> #define DRM_MODE_DIRTY_ON 1
> #define DRM_MODE_DIRTY_ANNOTATE 2
>
> +/* Link Status options */
> +#define DRM_MODE_LINK_STATUS_GOOD 0
> +#define DRM_MODE_LINK_STATUS_BAD 1
The change to reset link_status to good for SETCRTC seems to be missing.
Something like the below (totally untested) should get the job done.
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 494680c9056e..5f47049d611e 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -2258,6 +2258,8 @@ static int update_output_state(struct drm_atomic_state *state,
NULL);
if (ret)
return ret;
+
+ conn_state->link_status = DRM_LINK_STATUS_GOOD;
}
}
Small exercise for you: Follow the call chain of this function and figure
out how it works. And let's hope I did it right and it does work ;-)
Cheers, Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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