drm/fb-helper: Remove drm_fb_helper_crtc

struct drm_fb_helper_crtc is now just a wrapper around drm_mode_set so
use that directly instead and attach it as a modeset array onto
drm_client_dev. drm_fb_helper will use this array to store its modesets
which means it will always initialize a drm_client, but it will not
register the client (callbacks) unless it's the generic fbdev emulation.

Code will later be moved to drm_client, so add code there in a new file
drm_client_modeset.c with MIT license to match drm_fb_helper.c.

The modeset connector array size is hardcoded for the cloned case to avoid
having to pass in a value from the driver. A value of 8 is chosen to err
on the safe side. This means that the max connector argument for
drm_fb_helper_init() and drm_fb_helper_fbdev_setup() isn't used anymore,
a todo entry for this is added.

In pan_display_atomic() restore_fbdev_mode_force() is used instead of
restore_fbdev_mode_atomic() because that one will later become internal
to drm_client_modeset.

Locking order:
1. drm_fb_helper->lock
2. drm_master_internal_acquire
3. drm_client_dev->modeset_mutex

v6: Improve commit message (Sam Ravnborg)

v3:
- Use full drm_client_init/release for the modesets (Daniel Vetter)
- drm_client_for_each_modeset: use lockdep_assert_held (Daniel Vetter)
- Hook up to Documentation/gpu/drm-client.rst (Daniel Vetter)

v2:
- Add modesets array to drm_client (Daniel Vetter)
- Use a new file for the modeset code (Daniel Vetter)
- File has to be MIT licensed (Emmanuel Vadot)
- Add copyrights from drm_fb_helper.c
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190531140117.37751-3-noralf@tronnes.org

Documentation/gpu/drm-client.rst

@@ -10,3 +10,6 @@ Kernel clients
 
 .. kernel-doc:: drivers/gpu/drm/drm_client.c
    :export:
+
+.. kernel-doc:: drivers/gpu/drm/drm_client_modeset.c
+   :export:

Documentation/gpu/todo.rst

@@ -289,6 +289,9 @@ drm_fb_helper tasks
   these igt tests need to be fixed: kms_fbcon_fbt@psr and
   kms_fbcon_fbt@psr-suspend.
 
+- The max connector argument for drm_fb_helper_init() and
+  drm_fb_helper_fbdev_setup() isn't used anymore and can be removed.
+
 Core refactorings
 =================
 

drivers/gpu/drm/Makefile

@@ -17,7 +17,7 @@ drm-y       :=	drm_auth.o drm_cache.o \
 		drm_plane.o drm_color_mgmt.o drm_print.o \
 		drm_dumb_buffers.o drm_mode_config.o drm_vblank.o \
 		drm_syncobj.o drm_lease.o drm_writeback.o drm_client.o \
-		drm_atomic_uapi.o drm_hdcp.o
+		drm_client_modeset.o drm_atomic_uapi.o drm_hdcp.o
 
 drm-$(CONFIG_DRM_LEGACY) += drm_legacy_misc.o drm_bufs.o drm_context.o drm_dma.o drm_scatter.o drm_lock.o
 drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o

drivers/gpu/drm/drm_client.c

@@ -27,7 +27,6 @@
  * DOC: overview
  *
  * This library provides support for clients running in the kernel like fbdev and bootsplash.
- * Currently it's only partially implemented, just enough to support fbdev.
  *
  * GEM drivers which provide a GEM based dumb buffer with a virtual address are supported.
  */
@@ -92,14 +91,20 @@ int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
 	client->name = name;
 	client->funcs = funcs;
 
-	ret = drm_client_open(client);
+	ret = drm_client_modeset_create(client);
 	if (ret)
 		goto err_put_module;
 
+	ret = drm_client_open(client);
+	if (ret)
+		goto err_free;
+
 	drm_dev_get(dev);
 
 	return 0;
 
+err_free:
+	drm_client_modeset_free(client);
 err_put_module:
 	if (funcs)
 		module_put(funcs->owner);
@@ -148,6 +153,7 @@ void drm_client_release(struct drm_client_dev *client)
 
 	DRM_DEV_DEBUG_KMS(dev->dev, "%s\n", client->name);
 
+	drm_client_modeset_free(client);
 	drm_client_close(client);
 	drm_dev_put(dev);
 	if (client->funcs)

drivers/gpu/drm/drm_client_modeset.c

+// SPDX-License-Identifier: MIT
+/*
+ * Copyright 2018 Noralf Trønnes
+ * Copyright (c) 2006-2009 Red Hat Inc.
+ * Copyright (c) 2006-2008 Intel Corporation
+ *   Jesse Barnes <jesse.barnes@intel.com>
+ * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
+ */
+
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+
+#include <drm/drm_client.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_device.h>
+
+int drm_client_modeset_create(struct drm_client_dev *client)
+{
+	struct drm_device *dev = client->dev;
+	unsigned int num_crtc = dev->mode_config.num_crtc;
+	unsigned int max_connector_count = 1;
+	struct drm_mode_set *modeset;
+	struct drm_crtc *crtc;
+	unsigned int i = 0;
+
+	/* Add terminating zero entry to enable index less iteration */
+	client->modesets = kcalloc(num_crtc + 1, sizeof(*client->modesets), GFP_KERNEL);
+	if (!client->modesets)
+		return -ENOMEM;
+
+	mutex_init(&client->modeset_mutex);
+
+	drm_for_each_crtc(crtc, dev)
+		client->modesets[i++].crtc = crtc;
+
+	/* Cloning is only supported in the single crtc case. */
+	if (num_crtc == 1)
+		max_connector_count = DRM_CLIENT_MAX_CLONED_CONNECTORS;
+
+	for (modeset = client->modesets; modeset->crtc; modeset++) {
+		modeset->connectors = kcalloc(max_connector_count,
+					      sizeof(*modeset->connectors), GFP_KERNEL);
+		if (!modeset->connectors)
+			goto err_free;
+	}
+
+	return 0;
+
+err_free:
+	drm_client_modeset_free(client);
+
+	return -ENOMEM;
+}
+
+void drm_client_modeset_release(struct drm_client_dev *client)
+{
+	struct drm_mode_set *modeset;
+	unsigned int i;
+
+	drm_client_for_each_modeset(modeset, client) {
+		drm_mode_destroy(client->dev, modeset->mode);
+		modeset->mode = NULL;
+		modeset->fb = NULL;
+
+		for (i = 0; i < modeset->num_connectors; i++) {
+			drm_connector_put(modeset->connectors[i]);
+			modeset->connectors[i] = NULL;
+		}
+		modeset->num_connectors = 0;
+	}
+}
+/* TODO: Remove export when modeset code has been moved over */
+EXPORT_SYMBOL(drm_client_modeset_release);
+
+void drm_client_modeset_free(struct drm_client_dev *client)
+{
+	struct drm_mode_set *modeset;
+
+	mutex_lock(&client->modeset_mutex);
+
+	drm_client_modeset_release(client);
+
+	drm_client_for_each_modeset(modeset, client)
+		kfree(modeset->connectors);
+
+	mutex_unlock(&client->modeset_mutex);
+
+	mutex_destroy(&client->modeset_mutex);
+	kfree(client->modesets);
+}
+
+struct drm_mode_set *drm_client_find_modeset(struct drm_client_dev *client, struct drm_crtc *crtc)
+{
+	struct drm_mode_set *modeset;
+
+	drm_client_for_each_modeset(modeset, client)
+		if (modeset->crtc == crtc)
+			return modeset;
+
+	return NULL;
+}
+/* TODO: Remove export when modeset code has been moved over */
+EXPORT_SYMBOL(drm_client_find_modeset);

include/drm/drm_client.h

@@ -3,8 +3,12 @@
 #ifndef _DRM_CLIENT_H_
 #define _DRM_CLIENT_H_
 
+#include <linux/lockdep.h>
+#include <linux/mutex.h>
 #include <linux/types.h>
 
+#include <drm/drm_crtc.h>
+
 struct drm_client_dev;
 struct drm_device;
 struct drm_file;
@@ -13,6 +17,8 @@ struct drm_gem_object;
 struct drm_minor;
 struct module;
 
+#define DRM_CLIENT_MAX_CLONED_CONNECTORS	8
+
 /**
  * struct drm_client_funcs - DRM client callbacks
  */
@@ -85,6 +91,16 @@ struct drm_client_dev {
 	 * @file: DRM file
 	 */
 	struct drm_file *file;
+
+	/**
+	 * @modeset_mutex: Protects @modesets.
+	 */
+	struct mutex modeset_mutex;
+
+	/**
+	 * @modesets: CRTC configurations
+	 */
+	struct drm_mode_set *modesets;
 };
 
 int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
@@ -135,6 +151,20 @@ struct drm_client_buffer *
 drm_client_framebuffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format);
 void drm_client_framebuffer_delete(struct drm_client_buffer *buffer);
 
+int drm_client_modeset_create(struct drm_client_dev *client);
+void drm_client_modeset_free(struct drm_client_dev *client);
+void drm_client_modeset_release(struct drm_client_dev *client);
+struct drm_mode_set *drm_client_find_modeset(struct drm_client_dev *client, struct drm_crtc *crtc);
+
+/**
+ * drm_client_for_each_modeset() - Iterate over client modesets
+ * @modeset: &drm_mode_set loop cursor
+ * @client: DRM client
+ */
+#define drm_client_for_each_modeset(modeset, client) \
+	for (({ lockdep_assert_held(&(client)->modeset_mutex); }), \
+	     modeset = (client)->modesets; modeset->crtc; modeset++)
+
 int drm_client_debugfs_init(struct drm_minor *minor);
 
 #endif

include/drm/drm_fb_helper.h

@@ -47,10 +47,6 @@ struct drm_fb_offset {
 	int x, y;
 };
 
-struct drm_fb_helper_crtc {
-	struct drm_mode_set mode_set;
-};
-
 /**
  * struct drm_fb_helper_surface_size - describes fbdev size and scanout surface size
  * @fb_width: fbdev width
@@ -109,8 +105,6 @@ struct drm_fb_helper_connector {
  * struct drm_fb_helper - main structure to emulate fbdev on top of KMS
  * @fb: Scanout framebuffer object
  * @dev: DRM device
- * @crtc_count: number of possible CRTCs
- * @crtc_info: per-CRTC helper state (mode, x/y offset, etc)
  * @connector_count: number of connected connectors
  * @connector_info_alloc_count: size of connector_info
  * @funcs: driver callbacks for fb helper
@@ -144,8 +138,6 @@ struct drm_fb_helper {
 
 	struct drm_framebuffer *fb;
 	struct drm_device *dev;
-	int crtc_count;
-	struct drm_fb_helper_crtc *crtc_info;
 	int connector_count;
 	int connector_info_alloc_count;
 	/**