diff options
Diffstat (limited to 'include/drm')
| -rw-r--r-- | include/drm/drm_simple_kms_helper.h | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/include/drm/drm_simple_kms_helper.h b/include/drm/drm_simple_kms_helper.h index c4e32c5a18fc..1b4e352143fd 100644 --- a/include/drm/drm_simple_kms_helper.h +++ b/include/drm/drm_simple_kms_helper.h @@ -24,9 +24,30 @@ struct drm_simple_display_pipe_funcs { /** * @mode_valid: * - * This function is called to filter out valid modes from the - * suggestions suggested by the bridge or display. This optional - * hook is passed in when initializing the pipeline. + * This callback is used to check if a specific mode is valid in the + * crtc used in this simple display pipe. This should be implemented + * if the display pipe has some sort of restriction in the modes + * it can display. For example, a given display pipe may be responsible + * to set a clock value. If the clock can not produce all the values + * for the available modes then this callback can be used to restrict + * the number of modes to only the ones that can be displayed. Another + * reason can be bandwidth mitigation: the memory port on the display + * controller can have bandwidth limitations not allowing pixel data + * to be fetched at any rate. + * + * This hook is used by the probe helpers to filter the mode list in + * drm_helper_probe_single_connector_modes(), and it is used by the + * atomic helpers to validate modes supplied by userspace in + * drm_atomic_helper_check_modeset(). + * + * This function is optional. + * + * NOTE: + * + * Since this function is both called from the check phase of an atomic + * commit, and the mode validation in the probe paths it is not allowed + * to look at anything else but the passed-in mode, and validate it + * against configuration-invariant hardware constraints. * * RETURNS: * |