diff options
-rw-r--r-- | Documentation/DocBook/gpu.tmpl | 188 | ||||
-rw-r--r-- | include/drm/drm_modeset_helper_vtables.h | 44 |
2 files changed, 41 insertions, 191 deletions
diff --git a/Documentation/DocBook/gpu.tmpl b/Documentation/DocBook/gpu.tmpl index 225a246..faa5e0d 100644 --- a/Documentation/DocBook/gpu.tmpl +++ b/Documentation/DocBook/gpu.tmpl @@ -1579,194 +1579,6 @@ void intel_crt_init(struct drm_device *dev) entities. </para> <sect2> - <title>Legacy CRTC Helper Operations</title> - <itemizedlist> - <listitem id="drm-helper-crtc-mode-fixup"> - <synopsis>bool (*mode_fixup)(struct drm_crtc *crtc, - const struct drm_display_mode *mode, - struct drm_display_mode *adjusted_mode);</synopsis> - <para> - Let CRTCs adjust the requested mode or reject it completely. This - operation returns true if the mode is accepted (possibly after being - adjusted) or false if it is rejected. - </para> - <para> - The <methodname>mode_fixup</methodname> operation should reject the - mode if it can't reasonably use it. The definition of "reasonable" - is currently fuzzy in this context. One possible behaviour would be - to set the adjusted mode to the panel timings when a fixed-mode - panel is used with hardware capable of scaling. Another behaviour - would be to accept any input mode and adjust it to the closest mode - supported by the hardware (FIXME: This needs to be clarified). - </para> - </listitem> - <listitem> - <synopsis>int (*mode_set_base)(struct drm_crtc *crtc, int x, int y, - struct drm_framebuffer *old_fb)</synopsis> - <para> - Move the CRTC on the current frame buffer (stored in - <literal>crtc->fb</literal>) to position (x,y). Any of the frame - buffer, x position or y position may have been modified. - </para> - <para> - This helper operation is optional. If not provided, the - <function>drm_crtc_helper_set_config</function> function will fall - back to the <methodname>mode_set</methodname> helper operation. - </para> - <note><para> - FIXME: Why are x and y passed as arguments, as they can be accessed - through <literal>crtc->x</literal> and - <literal>crtc->y</literal>? - </para></note> - </listitem> - <listitem> - <synopsis>void (*prepare)(struct drm_crtc *crtc);</synopsis> - <para> - Prepare the CRTC for mode setting. This operation is called after - validating the requested mode. Drivers use it to perform - device-specific operations required before setting the new mode. - </para> - </listitem> - <listitem> - <synopsis>int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode, - struct drm_display_mode *adjusted_mode, int x, int y, - struct drm_framebuffer *old_fb);</synopsis> - <para> - Set a new mode, position and frame buffer. Depending on the device - requirements, the mode can be stored internally by the driver and - applied in the <methodname>commit</methodname> operation, or - programmed to the hardware immediately. - </para> - <para> - The <methodname>mode_set</methodname> operation returns 0 on success - or a negative error code if an error occurs. - </para> - </listitem> - <listitem> - <synopsis>void (*commit)(struct drm_crtc *crtc);</synopsis> - <para> - Commit a mode. This operation is called after setting the new mode. - Upon return the device must use the new mode and be fully - operational. - </para> - </listitem> - </itemizedlist> - </sect2> - <sect2> - <title>Encoder Helper Operations</title> - <itemizedlist> - <listitem> - <synopsis>bool (*mode_fixup)(struct drm_encoder *encoder, - const struct drm_display_mode *mode, - struct drm_display_mode *adjusted_mode);</synopsis> - <para> - Let encoders adjust the requested mode or reject it completely. This - operation returns true if the mode is accepted (possibly after being - adjusted) or false if it is rejected. See the - <link linkend="drm-helper-crtc-mode-fixup">mode_fixup CRTC helper - operation</link> for an explanation of the allowed adjustments. - </para> - </listitem> - <listitem> - <synopsis>void (*prepare)(struct drm_encoder *encoder);</synopsis> - <para> - Prepare the encoder for mode setting. This operation is called after - validating the requested mode. Drivers use it to perform - device-specific operations required before setting the new mode. - </para> - </listitem> - <listitem> - <synopsis>void (*mode_set)(struct drm_encoder *encoder, - struct drm_display_mode *mode, - struct drm_display_mode *adjusted_mode);</synopsis> - <para> - Set a new mode. Depending on the device requirements, the mode can - be stored internally by the driver and applied in the - <methodname>commit</methodname> operation, or programmed to the - hardware immediately. - </para> - </listitem> - <listitem> - <synopsis>void (*commit)(struct drm_encoder *encoder);</synopsis> - <para> - Commit a mode. This operation is called after setting the new mode. - Upon return the device must use the new mode and be fully - operational. - </para> - </listitem> - </itemizedlist> - </sect2> - <sect2> - <title>Connector Helper Operations</title> - <itemizedlist> - <listitem> - <synopsis>struct drm_encoder *(*best_encoder)(struct drm_connector *connector);</synopsis> - <para> - Return a pointer to the best encoder for the connecter. Device that - map connectors to encoders 1:1 simply return the pointer to the - associated encoder. This operation is mandatory. - </para> - </listitem> - <listitem> - <synopsis>int (*get_modes)(struct drm_connector *connector);</synopsis> - <para> - Fill the connector's <structfield>probed_modes</structfield> list - by parsing EDID data with <function>drm_add_edid_modes</function>, - adding standard VESA DMT modes with <function>drm_add_modes_noedid</function>, - or calling <function>drm_mode_probed_add</function> directly for every - supported mode and return the number of modes it has detected. This - operation is mandatory. - </para> - <para> - Note that the caller function will automatically add standard VESA - DMT modes up to 1024x768 if the <methodname>get_modes</methodname> - helper operation returns no mode and if the connector status is - connector_status_connected. There is no need to call - <function>drm_add_edid_modes</function> manually in that case. - </para> - <para> - The <structfield>vrefresh</structfield> value is computed by - <function>drm_helper_probe_single_connector_modes</function>. - </para> - <para> - When parsing EDID data, <function>drm_add_edid_modes</function> fills the - connector <structfield>display_info</structfield> - <structfield>width_mm</structfield> and - <structfield>height_mm</structfield> fields. When creating modes - manually the <methodname>get_modes</methodname> helper operation must - set the <structfield>display_info</structfield> - <structfield>width_mm</structfield> and - <structfield>height_mm</structfield> fields if they haven't been set - already (for instance at initialization time when a fixed-size panel is - attached to the connector). The mode <structfield>width_mm</structfield> - and <structfield>height_mm</structfield> fields are only used internally - during EDID parsing and should not be set when creating modes manually. - </para> - </listitem> - <listitem> - <synopsis>int (*mode_valid)(struct drm_connector *connector, - struct drm_display_mode *mode);</synopsis> - <para> - Verify whether a mode is valid for the connector. Return MODE_OK for - supported modes and one of the enum drm_mode_status values (MODE_*) - for unsupported modes. This operation is optional. - </para> - <para> - As the mode rejection reason is currently not used beside for - immediately removing the unsupported mode, an implementation can - return MODE_BAD regardless of the exact reason why the mode is not - valid. - </para> - <note><para> - Note that the <methodname>mode_valid</methodname> helper operation is - only called for modes detected by the device, and - <emphasis>not</emphasis> for modes set by the user through the CRTC - <methodname>set_config</methodname> operation. - </para></note> - </listitem> - </itemizedlist> - </sect2> - <sect2> <title>Atomic Modeset Helper Functions Reference</title> <sect3> <title>Overview</title> diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h index 29e0dc5..a126a0d 100644 --- a/include/drm/drm_modeset_helper_vtables.h +++ b/include/drm/drm_modeset_helper_vtables.h @@ -131,6 +131,20 @@ struct drm_crtc_helper_funcs { * Atomic drivers which need to inspect and adjust more state should * instead use the @atomic_check callback. * + * 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 + * ->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 ->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 ->mode_valid() but also in ->mode_fixup() to + * make sure invalid modes passed in from userspace are rejected. + * * RETURNS: * * True if an acceptable configuration is possible, false if the modeset @@ -188,7 +202,9 @@ struct drm_crtc_helper_funcs { * This callback is used by the legacy CRTC helpers to set a new * framebuffer and scanout position. It is optional and used as an * optimized fast-path instead of a full mode set operation with all the - * resulting flickering. Since it can't update other planes it's + * resulting flickering. If it is not present + * drm_crtc_helper_set_config() will fall back to a full modeset, using + * the ->mode_set() callback. Since it can't update other planes it's * incompatible with atomic modeset support. * * This callback is only used by the CRTC helpers and deprecated. @@ -439,6 +455,20 @@ struct drm_encoder_helper_funcs { * Atomic drivers which need to inspect and adjust more state should * instead use the @atomic_check callback. * + * 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 + * ->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 ->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 ->mode_valid() but also in ->mode_fixup() to + * make sure invalid modes passed in from userspace are rejected. + * * RETURNS: * * True if an acceptable configuration is possible, false if the modeset @@ -640,8 +670,16 @@ struct drm_connector_helper_funcs { * In this function drivers then parse the modes in the EDID and add * them by calling drm_add_edid_modes(). But connectors that driver a * fixed panel can also manually add specific modes using - * drm_mode_probed_add(). Finally drivers that support audio probably - * want to update the ELD data, too, using drm_edid_to_eld(). + * drm_mode_probed_add(). Drivers which manually add modes should also + * make sure that the @display_info, @width_mm and @height_mm fields of the + * struct #drm_connector are filled in. + * + * Virtual drivers that just want some standard VESA mode with a given + * resolution can call drm_add_modes_noedid(), and mark the preferred + * one using drm_set_preferred_mode(). + * + * Finally drivers that support audio probably want to update the ELD + * data, too, using drm_edid_to_eld(). * * This function is only called after the ->detect() hook has indicated * that a sink is connected and when the EDID isn't overridden through |