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drm/probe_helper: Add drm_connector_helper_funcs.mode_valid_ctx

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This is just an atomic version of mode_valid, which is intended to be
used for situations where a driver might need to check the atomic state
of objects other than the connector itself. One such example is with
MST, where the maximum possible bandwidth on a connector can change
dynamically irregardless of the display configuration.

Changes since v1:
* Use new drm logging functions
* Make some corrections in the mode_valid_ctx kdoc
* Return error codes or 0 from ->mode_valid_ctx() on fail, and store the
  drm_mode_status in an additional function parameter
Changes since v2:
* Don't accidentally assign ret to mode->status on success, or we'll
  squash legitimate mode validation results
* Don't forget to assign MODE_OK to status in drm_connector_mode_valid()
  if we have no callbacks
* Drop leftover hunk in drm_modes.h around enum drm_mode_status
Changes since v3:
* s/return ret/return 0/ in drm_mode_validate_pipeline()
* Minor cleanup in drm_connector_mode_valid()

Tested-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Cc: Lee Shawn C <shawn.c.lee@intel.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200713170746.254388-2-lyude@redhat.com
This commit is contained in:
Lyude Paul
2020-07-13 13:07:45 -04:00
parent 1d9221e9d3
commit 1c26b8e090
3 changed files with 110 additions and 34 deletions
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42
include/drm/drm_modeset_helper_vtables.h
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@@ -968,6 +968,48 @@ struct drm_connector_helper_funcs {
*/
enum drm_mode_status (*mode_valid)(struct drm_connector *connector,
struct drm_display_mode *mode);
/**
* @mode_valid_ctx:
*
* Callback to validate a mode for a connector, irrespective of the
* specific display configuration.
*
* This callback is used by the probe helpers to filter the mode list
* (which is usually derived from the EDID data block from the sink).
* See e.g. drm_helper_probe_single_connector_modes().
*
* This function is optional, and is the atomic version of
* &drm_connector_helper_funcs.mode_valid.
*
* To allow for accessing the atomic state of modesetting objects, the
* helper libraries always call this with ctx set to a valid context,
* and &drm_mode_config.connection_mutex will always be locked with
* the ctx parameter set to @ctx. This allows for taking additional
* locks as required.
*
* Even though additional locks may be acquired, this callback is
* still expected not to take any constraints into account which would
* be influenced by the currently set display state - such constraints
* should be handled in the driver's atomic check. For example, if a
* connector shares display bandwidth with other connectors then it
* would be ok to validate the minimum bandwidth requirement of a mode
* against the maximum possible bandwidth of the connector. But it
* wouldn't be ok to take the current bandwidth usage of other
* connectors into account, as this would change depending on the
* display state.
*
* Returns:
* 0 if &drm_connector_helper_funcs.mode_valid_ctx succeeded and wrote
* the &enum drm_mode_status value to @status, or a negative error
* code otherwise.
*
*/
int (*mode_valid_ctx)(struct drm_connector *connector,
struct drm_display_mode *mode,
struct drm_modeset_acquire_ctx *ctx,
enum drm_mode_status *status);
/**
* @best_encoder:
*