drm: Add primary plane helpers (v3)

When we expose non-overlay planes to userspace, they will become
accessible via standard userspace plane API's. We should be able to
handle the standard plane operations against primary planes in a generic
way via the modeset handler.

Drivers that can program primary planes more efficiently, that want to
use their own primary plane structure to track additional information,
or that don't have the limitations assumed by the helpers are free to
provide their own implementation of some or all of these handlers.

v3: Tweak kerneldoc formatting slightly to avoid ugliness
v2:
- Move plane helpers to a new file (drm_plane_helper.c)
- Tighten checks on update handler (check for scaling, CRTC coverage,
subpixel positioning)
- Pass proper panning parameters to modeset interface
- Disallow disabling primary plane (and thus CRTC) if other planes are
still active on the CRTC.
- Use a minimal format list that should work on all hardware/drivers.
Drivers may call this function with a more accurate plane list to
enable additional formats they can support.

Signed-off-by: Matt Roper <[e-mail]>
Reviewed-by: Rob Clark <[e-mail]>

drivers/gpu/drm/Makefile

···
 		drm_crtc.o drm_modes.o drm_edid.o \
 		drm_info.o drm_debugfs.o drm_encoder_slave.o \
 		drm_trace_points.o drm_global.o drm_prime.o \
-		drm_rect.o drm_vma_manager.o drm_flip_work.o
+		drm_rect.o drm_vma_manager.o drm_flip_work.o \
+		drm_plane_helper.o
 
 drm-$(CONFIG_COMPAT) += drm_ioc32.o
 drm-$(CONFIG_DRM_GEM_CMA_HELPER) += drm_gem_cma_helper.o

drivers/gpu/drm/drm_plane_helper.c

···
+/*
+ * Copyright (C) 2014 Intel Corporation
+ *
+ * DRM universal plane helper functions
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <linux/list.h>
+#include <drm/drmP.h>
+#include <drm/drm_rect.h>
+
+#define SUBPIXEL_MASK 0xffff
+
+/*
+ * This is the minimal list of formats that seem to be safe for modeset use
+ * with all current DRM drivers.  Most hardware can actually support more
+ * formats than this and drivers may specify a more accurate list when
+ * creating the primary plane.  However drivers that still call
+ * drm_plane_init() will use this minimal format list as the default.
+ */
+const static uint32_t safe_modeset_formats[] = {
+       DRM_FORMAT_XRGB8888,
+       DRM_FORMAT_ARGB8888,
+};
+
+/*
+ * Returns the connectors currently associated with a CRTC.  This function
+ * should be called twice:  once with a NULL connector list to retrieve
+ * the list size, and once with the properly allocated list to be filled in.
+ */
+static int get_connectors_for_crtc(struct drm_crtc *crtc,
+				   struct drm_connector **connector_list,
+				   int num_connectors)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_connector *connector;
+	int count = 0;
+
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head)
+		if (connector->encoder && connector->encoder->crtc == crtc) {
+			if (connector_list != NULL && count < num_connectors)
+				*(connector_list++) = connector;
+
+			count++;
+		}
+
+	return count;
+}
+
+/**
+ * drm_primary_helper_update() - Helper for primary plane update
+ * @plane: plane object to update
+ * @crtc: owning CRTC of owning plane
+ * @fb: framebuffer to flip onto plane
+ * @crtc_x: x offset of primary plane on crtc
+ * @crtc_y: y offset of primary plane on crtc
+ * @crtc_w: width of primary plane rectangle on crtc
+ * @crtc_h: height of primary plane rectangle on crtc
+ * @src_x: x offset of @fb for panning
+ * @src_y: y offset of @fb for panning
+ * @src_w: width of source rectangle in @fb
+ * @src_h: height of source rectangle in @fb
+ *
+ * Provides a default plane update handler for primary planes.  This is handler
+ * is called in response to a userspace SetPlane operation on the plane with a
+ * non-NULL framebuffer.  We call the driver's modeset handler to update the
+ * framebuffer.
+ *
+ * SetPlane() on a primary plane of a disabled CRTC is not supported, and will
+ * return an error.
+ *
+ * Note that we make some assumptions about hardware limitations that may not be
+ * true for all hardware --
+ *   1) Primary plane cannot be repositioned.
+ *   2) Primary plane cannot be scaled.
+ *   3) Primary plane must cover the entire CRTC.
+ *   4) Subpixel positioning is not supported.
+ * Drivers for hardware that don't have these restrictions can provide their
+ * own implementation rather than using this helper.
+ *
+ * RETURNS:
+ * Zero on success, error code on failure
+ */
+int drm_primary_helper_update(struct drm_plane *plane, struct drm_crtc *crtc,
+			      struct drm_framebuffer *fb,
+			      int crtc_x, int crtc_y,
+			      unsigned int crtc_w, unsigned int crtc_h,
+			      uint32_t src_x, uint32_t src_y,
+			      uint32_t src_w, uint32_t src_h)
+{
+	struct drm_mode_set set = {
+		.crtc = crtc,
+		.fb = fb,
+		.mode = &crtc->mode,
+		.x = src_x >> 16,
+		.y = src_y >> 16,
+	};
+	struct drm_rect dest = {
+		.x1 = crtc_x,
+		.y1 = crtc_y,
+		.x2 = crtc_x + crtc_w,
+		.y2 = crtc_y + crtc_h,
+	};
+	struct drm_rect clip = {
+		.x2 = crtc->mode.hdisplay,
+		.y2 = crtc->mode.vdisplay,
+	};
+	struct drm_connector **connector_list;
+	struct drm_framebuffer *tmpfb;
+	int num_connectors, ret;
+
+	if (!crtc->enabled) {
+		DRM_DEBUG_KMS("Cannot update primary plane of a disabled CRTC.\n");
+		return -EINVAL;
+	}
+
+	/* Disallow subpixel positioning */
+	if ((src_x | src_y | src_w | src_h) & SUBPIXEL_MASK) {
+		DRM_DEBUG_KMS("Primary plane does not support subpixel positioning\n");
+		return -EINVAL;
+	}
+
+	/* Primary planes are locked to their owning CRTC */
+	if (plane->possible_crtcs != drm_crtc_mask(crtc)) {
+		DRM_DEBUG_KMS("Cannot change primary plane CRTC\n");
+		return -EINVAL;
+	}
+
+	/* Disallow scaling */
+	if (crtc_w != src_w || crtc_h != src_h) {
+		DRM_DEBUG_KMS("Can't scale primary plane\n");
+		return -EINVAL;
+	}
+
+	/* Make sure primary plane covers entire CRTC */
+	drm_rect_intersect(&dest, &clip);
+	if (dest.x1 != 0 || dest.y1 != 0 ||
+	    dest.x2 != crtc->mode.hdisplay || dest.y2 != crtc->mode.vdisplay) {
+		DRM_DEBUG_KMS("Primary plane must cover entire CRTC\n");
+		return -EINVAL;
+	}
+
+	/* Framebuffer must be big enough to cover entire plane */
+	ret = drm_crtc_check_viewport(crtc, crtc_x, crtc_y, &crtc->mode, fb);
+	if (ret)
+		return ret;
+
+	/* Find current connectors for CRTC */
+	num_connectors = get_connectors_for_crtc(crtc, NULL, 0);
+	BUG_ON(num_connectors == 0);
+	connector_list = kzalloc(num_connectors * sizeof(*connector_list),
+				 GFP_KERNEL);
+	if (!connector_list)
+		return -ENOMEM;
+	get_connectors_for_crtc(crtc, connector_list, num_connectors);
+
+	set.connectors = connector_list;
+	set.num_connectors = num_connectors;
+
+	/*
+	 * set_config() adjusts crtc->primary->fb; however the DRM setplane
+	 * code that called us expects to handle the framebuffer update and
+	 * reference counting; save and restore the current fb before
+	 * calling it.
+	 *
+	 * N.B., we call set_config() directly here rather than using
+	 * drm_mode_set_config_internal.  We're reprogramming the same
+	 * connectors that were already in use, so we shouldn't need the extra
+	 * cross-CRTC fb refcounting to accomodate stealing connectors.
+	 * drm_mode_setplane() already handles the basic refcounting for the
+	 * framebuffers involved in this operation.
+	 */
+	tmpfb = plane->fb;
+	ret = crtc->funcs->set_config(&set);
+	plane->fb = tmpfb;
+
+	kfree(connector_list);
+	return ret;
+}
+EXPORT_SYMBOL(drm_primary_helper_update);
+
+/**
+ * drm_primary_helper_disable() - Helper for primary plane disable
+ * @plane: plane to disable
+ *
+ * Provides a default plane disable handler for primary planes.  This is handler
+ * is called in response to a userspace SetPlane operation on the plane with a
+ * NULL framebuffer parameter.  We call the driver's modeset handler with a NULL
+ * framebuffer to disable the CRTC if no other planes are currently enabled.
+ * If other planes are still enabled on the same CRTC, we return -EBUSY.
+ *
+ * Note that some hardware may be able to disable the primary plane without
+ * disabling the whole CRTC.  Drivers for such hardware should provide their
+ * own disable handler that disables just the primary plane (and they'll likely
+ * need to provide their own update handler as well to properly re-enable a
+ * disabled primary plane).
+ *
+ * RETURNS:
+ * Zero on success, error code on failure
+ */
+int drm_primary_helper_disable(struct drm_plane *plane)
+{
+	struct drm_plane *p;
+	struct drm_mode_set set = {
+		.crtc = plane->crtc,
+		.fb = NULL,
+	};
+
+	if (plane->crtc == NULL || plane->fb == NULL)
+		/* Already disabled */
+		return 0;
+
+	list_for_each_entry(p, &plane->dev->mode_config.plane_list, head)
+		if (p != plane && p->fb) {
+			DRM_DEBUG_KMS("Cannot disable primary plane while other planes are still active on CRTC.\n");
+			return -EBUSY;
+		}
+
+	/*
+	 * N.B.  We call set_config() directly here rather than
+	 * drm_mode_set_config_internal() since drm_mode_setplane() already
+	 * handles the basic refcounting and we don't need the special
+	 * cross-CRTC refcounting (no chance of stealing connectors from
+	 * other CRTC's with this update).
+	 */
+	return plane->crtc->funcs->set_config(&set);
+}
+EXPORT_SYMBOL(drm_primary_helper_disable);
+
+/**
+ * drm_primary_helper_destroy() - Helper for primary plane destruction
+ * @plane: plane to destroy
+ *
+ * Provides a default plane destroy handler for primary planes.  This handler
+ * is called during CRTC destruction.  We disable the primary plane, remove
+ * it from the DRM plane list, and deallocate the plane structure.
+ */
+void drm_primary_helper_destroy(struct drm_plane *plane)
+{
+	plane->funcs->disable_plane(plane);
+	drm_plane_cleanup(plane);
+	kfree(plane);
+}
+EXPORT_SYMBOL(drm_primary_helper_destroy);
+
+const struct drm_plane_funcs drm_primary_helper_funcs = {
+	.update_plane = drm_primary_helper_update,
+	.disable_plane = drm_primary_helper_disable,
+	.destroy = drm_primary_helper_destroy,
+};
+EXPORT_SYMBOL(drm_primary_helper_funcs);
+
+/**
+ * drm_primary_helper_create_plane() - Create a generic primary plane
+ * @dev: drm device
+ * @formats: pixel formats supported, or NULL for a default safe list
+ * @num_formats: size of @formats; ignored if @formats is NULL
+ *
+ * Allocates and initializes a primary plane that can be used with the primary
+ * plane helpers.  Drivers that wish to use driver-specific plane structures or
+ * provide custom handler functions may perform their own allocation and
+ * initialization rather than calling this function.
+ */
+struct drm_plane *drm_primary_helper_create_plane(struct drm_device *dev,
+						  const uint32_t *formats,
+						  int num_formats)
+{
+	struct drm_plane *primary;
+	int ret;
+
+	primary = kzalloc(sizeof(*primary), GFP_KERNEL);
+	if (primary == NULL) {
+		DRM_DEBUG_KMS("Failed to allocate primary plane\n");
+		return NULL;
+	}
+
+	if (formats == NULL) {
+		formats = safe_modeset_formats;
+		num_formats = ARRAY_SIZE(safe_modeset_formats);
+	}
+
+	/* possible_crtc's will be filled in later by crtc_init */
+	ret = drm_plane_init(dev, primary, 0, &drm_primary_helper_funcs,
+			     formats, num_formats,
+			     DRM_PLANE_TYPE_PRIMARY);
+	if (ret) {
+		kfree(primary);
+		primary = NULL;
+	}
+
+	return primary;
+}
+EXPORT_SYMBOL(drm_primary_helper_create_plane);
+

include/drm/drm_plane_helper.h

···
+/*
+ * Copyright (C) 2011-2013 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef DRM_PLANE_HELPER_H
+#define DRM_PLANE_HELPER_H
+
+/**
+ * DOC: plane helpers
+ *
+ * Helper functions to assist with creation and handling of CRTC primary
+ * planes.
+ */
+
+extern int drm_primary_helper_update(struct drm_plane *plane,
+				     struct drm_crtc *crtc,
+				     struct drm_framebuffer *fb,
+				     int crtc_x, int crtc_y,
+				     unsigned int crtc_w, unsigned int crtc_h,
+				     uint32_t src_x, uint32_t src_y,
+				     uint32_t src_w, uint32_t src_h);
+extern int drm_primary_helper_disable(struct drm_plane *plane);
+extern void drm_primary_helper_destroy(struct drm_plane *plane);
+extern const struct drm_plane_funcs drm_primary_helper_funcs;
+extern struct drm_plane *drm_primary_helper_create_plane(struct drm_device *dev,
+							 uint32_t *formats,
+							 int num_formats);
+
+
+#endif