[PATCH v3 1/6] drm: Add crtc/encoder/bridge->mode_valid() callbacks
Daniel Vetter
daniel at ffwll.ch
Fri May 12 07:00:27 UTC 2017
On Thu, May 11, 2017 at 10:05:57AM +0100, Jose Abreu wrote:
> This adds a new callback to crtc, encoder and bridge helper functions
> called mode_valid(). This callback shall be implemented if the
> corresponding component has some sort of restriction in the modes
> that can be displayed. A NULL callback implicates that the component
> can display all the modes.
>
> We also change the documentation so that the new and old callbacks
> are correctly documented.
>
> Only the callbacks were implemented to simplify review process,
> following patches will make use of them.
>
> Signed-off-by: Jose Abreu <joabreu at synopsys.com>
> Cc: Carlos Palminha <palminha at synopsys.com>
> Cc: Alexey Brodkin <abrodkin at synopsys.com>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Dave Airlie <airlied at linux.ie>
> Cc: Andrzej Hajda <a.hajda at samsung.com>
> Cc: Archit Taneja <architt at codeaurora.org>
> ---
>
> Changes v2->v3:
> - Try to document the callbacks a little bit better and
> review current documentation (Daniel)
Not quite what I had in mind, all the language about "Please be aware that
neither core nor helper filter modes" is still there. And that was added
to explain the difference between mode_valid and mode_fixup.
Since all the other patches look good I'll take stab at a v3 myself.
-Daniel
> Changes v1->v2:
> - Change description of connector->mode_valid() (Daniel)
>
> include/drm/drm_bridge.h | 20 ++++++
> include/drm/drm_modeset_helper_vtables.h | 110 +++++++++++++++++++++++--------
> 2 files changed, 103 insertions(+), 27 deletions(-)
>
> diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> index fdd82fc..00c6c36 100644
> --- a/include/drm/drm_bridge.h
> +++ b/include/drm/drm_bridge.h
> @@ -59,6 +59,26 @@ struct drm_bridge_funcs {
> void (*detach)(struct drm_bridge *bridge);
>
> /**
> + * @mode_valid:
> + *
> + * This callback is used to check if a specific mode is valid in this
> + * bridge. This should be implemented if the bridge has some sort of
> + * restriction in the modes it can display. For example, a given bridge
> + * 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.
> + *
> + * This is called at mode probe and at atomic check phase.
> + *
> + * RETURNS:
> + *
> + * drm_mode_status Enum
> + */
> + enum drm_mode_status (*mode_valid)(struct drm_bridge *crtc,
> + const struct drm_display_mode *mode);
> +
> + /**
> * @mode_fixup:
> *
> * This callback is used to validate and adjust a mode. The paramater
> diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
> index c01c328..b07b7cd 100644
> --- a/include/drm/drm_modeset_helper_vtables.h
> +++ b/include/drm/drm_modeset_helper_vtables.h
> @@ -106,14 +106,37 @@ struct drm_crtc_helper_funcs {
> void (*commit)(struct drm_crtc *crtc);
>
> /**
> + * @mode_valid:
> + *
> + * This callback is used to check if a specific mode is valid in this
> + * crtc. This should be implemented if the crtc has some sort of
> + * restriction in the modes it can display. For example, a given crtc
> + * 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.
> + *
> + * This is called at mode probe and at atomic check phase.
> + *
> + * RETURNS:
> + *
> + * drm_mode_status Enum
> + */
> + enum drm_mode_status (*mode_valid)(struct drm_crtc *crtc,
> + const struct drm_display_mode *mode);
> +
> + /**
> * @mode_fixup:
> *
> - * This callback is used to validate a mode. The parameter mode is the
> - * display mode that userspace requested, adjusted_mode is the mode the
> - * encoders need to be fed with. Note that this is the inverse semantics
> - * of the meaning for the &drm_encoder and &drm_bridge_funcs.mode_fixup
> - * vfunc. If the CRTC cannot support the requested conversion from mode
> - * to adjusted_mode it should reject the modeset.
> + * This callback is used to do the validation of an adjusted mode in the
> + * crtc. The parameter mode is the display mode that userspace requested,
> + * adjusted_mode is the mode the encoders need to be fed with. Note that
> + * this is the inverse semantics of the meaning for the &drm_encoder and
> + * &drm_bridge_funcs.mode_fixup vfunc. If the CRTC cannot support the
> + * requested conversion from mode to adjusted_mode it should reject the
> + * modeset. Also note that initial validation of a mode supplied by
> + * userspace should be done in &drm_crtc_helper_funcs.mode_valid and not
> + * in this callback.
> *
> * This function is used by both legacy CRTC helpers and atomic helpers.
> * With atomic helpers it is optional.
> @@ -135,17 +158,19 @@ struct drm_crtc_helper_funcs {
> * Also beware that neither core nor helpers filter modes before
> * passing them to the driver: While the list of modes that is
> * advertised to userspace is filtered using the
> - * &drm_connector.mode_valid callback, neither the core nor the helpers
> - * do any filtering on modes passed in from userspace when setting a
> - * mode. It is therefore possible for userspace to pass in a mode that
> - * was previously filtered out using &drm_connector.mode_valid or add a
> - * custom mode that wasn't probed from EDID or similar to begin with.
> - * Even though this is an advanced feature and rarely used nowadays,
> - * some users rely on being able to specify modes manually so drivers
> - * must be prepared to deal with it. Specifically this means that all
> - * drivers need not only validate modes in &drm_connector.mode_valid but
> - * also in this or in the &drm_encoder_helper_funcs.mode_fixup callback
> - * to make sure invalid modes passed in from userspace are rejected.
> + * &drm_connector_helper_funcs.mode_valid callback, neither the core nor
> + * the helpers do any filtering on modes passed in from userspace when
> + * setting a mode. It is therefore possible for userspace to pass in a
> + * mode that was previously filtered out using
> + * &drm_connector_helper_funcs.mode_valid or add a custom mode that
> + * wasn't probed from EDID or similar to begin with. Even though this
> + * is an advanced feature and rarely used nowadays, some users rely on
> + * being able to specify modes manually so drivers must be prepared to
> + * deal with it. Specifically this means that all drivers need not only
> + * validate modes in &drm_connector.mode_valid but also in this or in
> + * the &drm_crtc_helper_funcs.mode_valid,
> + * &drm_encoder_helper_funcs.mode_valid and &drm_bridge_funcs.mode_valid
> + * callbacks, where applicable.
> *
> * RETURNS:
> *
> @@ -457,11 +482,31 @@ struct drm_encoder_helper_funcs {
> void (*dpms)(struct drm_encoder *encoder, int mode);
>
> /**
> + * @mode_valid:
> + *
> + * This callback is used to check if a specific mode is valid in this
> + * encoder. This should be implemented if the encoder has some sort
> + * of restriction in the modes it can display. For example, a given
> + * encoder 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.
> + *
> + * This is called at mode probe and at atomic check phase.
> + *
> + * RETURNS:
> + *
> + * drm_mode_status Enum
> + */
> + enum drm_mode_status (*mode_valid)(struct drm_encoder *crtc,
> + const struct drm_display_mode *mode);
> +
> + /**
> * @mode_fixup:
> *
> - * This callback is used to validate and adjust a mode. The parameter
> - * mode is the display mode that should be fed to the next element in
> - * the display chain, either the final &drm_connector or a &drm_bridge.
> + * This callback is used to adjust a mode. The parameter mode is the
> + * display mode that should be fed to the next element in the display
> + * chain, either the final &drm_connector or a &drm_bridge.
> * The parameter adjusted_mode is the input mode the encoder requires. It
> * can be modified by this callback and does not need to match mode.
> *
> @@ -484,19 +529,20 @@ struct drm_encoder_helper_funcs {
> *
> * Also beware that neither core nor helpers filter modes before
> * passing them to the driver: While the list of modes that is
> - * advertised to userspace is filtered using the connector's
> + * advertised to userspace is filtered using the
> * &drm_connector_helper_funcs.mode_valid callback, neither the core nor
> * the helpers do any filtering on modes passed in from userspace when
> * setting a mode. It is therefore possible for userspace to pass in a
> * mode that was previously filtered out using
> * &drm_connector_helper_funcs.mode_valid or add a custom mode that
> - * wasn't probed from EDID or similar to begin with. Even though this
> + * wasn't probed from EDID or similar to begin with. Even though this
> * is an advanced feature and rarely used nowadays, some users rely on
> * being able to specify modes manually so drivers must be prepared to
> * deal with it. Specifically this means that all drivers need not only
> * validate modes in &drm_connector.mode_valid but also in this or in
> - * the &drm_crtc_helper_funcs.mode_fixup callback to make sure
> - * invalid modes passed in from userspace are rejected.
> + * the &drm_crtc_helper_funcs.mode_valid,
> + * &drm_encoder_helper_funcs.mode_valid and &drm_bridge_funcs.mode_valid
> + * callbacks, where applicable.
> *
> * RETURNS:
> *
> @@ -795,13 +841,23 @@ struct drm_connector_helper_funcs {
> * (which is usually derived from the EDID data block from the sink).
> * See e.g. drm_helper_probe_single_connector_modes().
> *
> + * This callback is never called in atomic check phase so that userspace
> + * can override kernel sink checks in case of broken EDID with wrong
> + * limits from the sink. You can use the remaining mode_valid()
> + * callbacks to validate the mode against your video path.
> + *
> * NOTE:
> *
> * This only filters the mode list supplied to userspace in the
> - * GETCONNECOTR IOCTL. Userspace is free to create modes of its own and
> + * GETCONNECTOR IOCTL. Userspace is free to create modes of its own and
> * ask the kernel to use them. It this case the atomic helpers or legacy
> - * CRTC helpers will not call this function. Drivers therefore must
> - * still fully validate any mode passed in in a modeset request.
> + * CRTC helpers will not call this function but the mode will be
> + * validated in atomic check phase using the mode_valid() callbacks
> + * (&drm_crtc_helper_funcs.mode_valid, &drm_encoder_helper_funcs.mode_valid
> + * and &drm_bridge_funcs.mode_valid).
> + * Drivers therefore must implement the mode_valid() callbacks if the
> + * video pipeline has some sort of restrictions in the modes that can
> + * be displayed.
> *
> * To avoid races with concurrent connector state updates, the helper
> * libraries always call this with the &drm_mode_config.connection_mutex
> --
> 1.9.1
>
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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