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fbdev: Handle video= parameter in video/cmdline.c
authorThomas Zimmermann <tzimmermann@suse.de>
Thu, 9 Feb 2023 13:55:06 +0000 (14:55 +0100)
committerThomas Zimmermann <tzimmermann@suse.de>
Mon, 20 Feb 2023 13:56:48 +0000 (14:56 +0100)
Handle the command-line parameter video= in video/cmdline.c. Implement
the fbdev helper fb_get_options() on top. Will allows to handle the
kernel parameter in DRM without fbdev dependencies.

Note that __video_get_options() has the meaning of its return value
inverted compared to fb_get_options(). The new helper returns true if
the adapter has been enabled, and false otherwise.

There is the ofonly parameter, which disables output for non-OF-based
framebuffers. It is only for offb and looks like a workaround. The actual
purpose it not clear to me. Use 'video=off' or 'nomodeset' instead.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230209135509.7786-9-tzimmermann@suse.de
drivers/gpu/drm/Kconfig
drivers/video/Kconfig
drivers/video/Makefile
drivers/video/cmdline.c [new file with mode: 0644]
drivers/video/fbdev/Kconfig
drivers/video/fbdev/core/Makefile
drivers/video/fbdev/core/fb_cmdline.c
include/video/cmdline.h [new file with mode: 0644]

index f42d4c6..17d252d 100644 (file)
@@ -10,13 +10,13 @@ menuconfig DRM
        depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && HAS_DMA
        select DRM_PANEL_ORIENTATION_QUIRKS
        select HDMI
-       select FB_CMDLINE
        select I2C
        select DMA_SHARED_BUFFER
        select SYNC_FILE
 # gallium uses SYS_kcmp for os_same_file_description() to de-duplicate
 # device and dmabuf fd. Let's make sure that is available for our userspace.
        select KCMP
+       select VIDEO_CMDLINE
        select VIDEO_NOMODESET
        help
          Kernel-level support for the Direct Rendering Infrastructure (DRI)
index 6d2fde6..bf05363 100644 (file)
@@ -11,6 +11,9 @@ config APERTURE_HELPERS
          Support tracking and hand-over of aperture ownership. Required
          by graphics drivers for firmware-provided framebuffers.
 
+config VIDEO_CMDLINE
+       bool
+
 config VIDEO_NOMODESET
        bool
        default n
index a50eb52..831c9fa 100644 (file)
@@ -2,6 +2,7 @@
 
 obj-$(CONFIG_APERTURE_HELPERS)    += aperture.o
 obj-$(CONFIG_VGASTATE)            += vgastate.o
+obj-$(CONFIG_VIDEO_CMDLINE)       += cmdline.o
 obj-$(CONFIG_VIDEO_NOMODESET)     += nomodeset.o
 obj-$(CONFIG_HDMI)                += hdmi.o
 
diff --git a/drivers/video/cmdline.c b/drivers/video/cmdline.c
new file mode 100644 (file)
index 0000000..d3d2574
--- /dev/null
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Based on the fbdev code in drivers/video/fbdev/core/fb_cmdline:
+ *
+ *  Copyright (C) 2014 Intel Corp
+ *  Copyright (C) 1994 Martin Schaller
+ *
+ *     2001 - Documented with DocBook
+ *     - Brad Douglas <brad@neruo.com>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file COPYING in the main directory of this archive
+ * for more details.
+ *
+ * Authors:
+ *    Daniel Vetter <daniel.vetter@ffwll.ch>
+ */
+
+#include <linux/fb.h> /* for FB_MAX */
+#include <linux/init.h>
+
+#include <video/cmdline.h>
+
+/*
+ * FB_MAX is the maximum number of framebuffer devices and also
+ * the maximum number of video= parameters. Although not directly
+ * related to each other, it makes sense to keep it that way.
+ */
+static const char *video_options[FB_MAX] __read_mostly;
+static const char *video_option __read_mostly;
+static int video_of_only __read_mostly;
+
+static const char *__video_get_option_string(const char *name)
+{
+       const char *options = NULL;
+       size_t name_len = 0;
+
+       if (name)
+               name_len = strlen(name);
+
+       if (name_len) {
+               unsigned int i;
+               const char *opt;
+
+               for (i = 0; i < ARRAY_SIZE(video_options); ++i) {
+                       if (!video_options[i])
+                               continue;
+                       if (video_options[i][0] == '\0')
+                               continue;
+                       opt = video_options[i];
+                       if (!strncmp(opt, name, name_len) && opt[name_len] == ':')
+                               options = opt + name_len + 1;
+               }
+       }
+
+       /* No match, return global options */
+       if (!options)
+               options = video_option;
+
+       return options;
+}
+
+/**
+ * video_get_options - get kernel boot parameters
+ * @name:      name of the output as it would appear in the boot parameter
+ *             line (video=<name>:<options>)
+ *
+ * Looks up the video= options for the given name. Names are connector
+ * names with DRM, or driver names with fbdev. If no video option for
+ * the name has been specified, the function returns the global video=
+ * setting. A @name of NULL always returns the global video setting.
+ *
+ * Returns:
+ * The string of video options for the given name, or NULL if no video
+ * option has been specified.
+ */
+const char *video_get_options(const char *name)
+{
+       return __video_get_option_string(name);
+}
+EXPORT_SYMBOL(video_get_options);
+
+bool __video_get_options(const char *name, const char **options, bool is_of)
+{
+       bool enabled = true;
+       const char *opt = NULL;
+
+       if (video_of_only && !is_of)
+               enabled = false;
+
+       opt = __video_get_option_string(name);
+
+       if (options)
+               *options = opt;
+
+       return enabled;
+}
+EXPORT_SYMBOL(__video_get_options);
+
+/*
+ * Process command line options for video adapters. This function is
+ * a __setup and __init function. It only stores the options. Drivers
+ * have to call video_get_options() as necessary.
+ */
+static int __init video_setup(char *options)
+{
+       if (!options || !*options)
+               goto out;
+
+       if (!strncmp(options, "ofonly", 6)) {
+               video_of_only = true;
+               goto out;
+       }
+
+       if (strchr(options, ':')) {
+               /* named */
+               size_t i;
+
+               for (i = 0; i < ARRAY_SIZE(video_options); i++) {
+                       if (!video_options[i]) {
+                               video_options[i] = options;
+                               break;
+                       }
+               }
+       } else {
+               /* global */
+               video_option = options;
+       }
+
+out:
+       return 1;
+}
+__setup("video=", video_setup);
index b2bed59..3623c1c 100644 (file)
@@ -3,16 +3,13 @@
 # fbdev configuration
 #
 
-config FB_CMDLINE
-       bool
-
 config FB_NOTIFY
        bool
 
 menuconfig FB
        tristate "Support for frame buffer devices"
-       select FB_CMDLINE
        select FB_NOTIFY
+       select VIDEO_CMDLINE
        help
          The frame buffer device provides an abstraction for the graphics
          hardware. It represents the frame buffer of some video hardware and
index 26cbc96..08fabce 100644 (file)
@@ -1,9 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
-obj-$(CONFIG_FB_CMDLINE)          += fb_cmdline.o
 obj-$(CONFIG_FB_NOTIFY)           += fb_notify.o
 obj-$(CONFIG_FB)                  += fb.o
 fb-y                              := fbmem.o fbmon.o fbcmap.o fbsysfs.o \
-                                     modedb.o fbcvt.o
+                                     modedb.o fbcvt.o fb_cmdline.o
 fb-$(CONFIG_FB_DEFERRED_IO)       += fb_defio.o
 
 ifeq ($(CONFIG_FRAMEBUFFER_CONSOLE),y)
index f811c7b..4d1634c 100644 (file)
  * Authors:
  *    Daniel Vetter <daniel.vetter@ffwll.ch>
  */
-#include <linux/init.h>
-#include <linux/fb.h>
-
-static char *video_options[FB_MAX] __read_mostly;
-static const char *fb_mode_option __read_mostly;
-static int ofonly __read_mostly;
-
-static const char *__fb_get_options(const char *name)
-{
-       const char *options = NULL;
-       size_t name_len = 0;
-
-       if (name)
-               name_len = strlen(name);
 
-       if (name_len) {
-               unsigned int i;
-               const char *opt;
-
-               for (i = 0; i < ARRAY_SIZE(video_options); ++i) {
-                       if (!video_options[i])
-                               continue;
-                       if (video_options[i][0] == '\0')
-                               continue;
-                       opt = video_options[i];
-                       if (!strncmp(opt, name, name_len) && opt[name_len] == ':')
-                               options = opt + name_len + 1;
-               }
-       }
+#include <linux/export.h>
+#include <linux/fb.h>
+#include <linux/string.h>
 
-       /* No match, return global options */
-       if (!options)
-               options = fb_mode_option;
-
-       return options;
-}
+#include <video/cmdline.h>
 
 /**
  * fb_get_options - get kernel boot parameters
@@ -65,17 +35,18 @@ static const char *__fb_get_options(const char *name)
  */
 int fb_get_options(const char *name, char **option)
 {
-       int retval = 0;
-       const char *options;
+       const char *options = NULL;
+       bool is_of = false;
+       bool enabled;
 
-       if (name && ofonly && strncmp(name, "offb", 4))
-               retval = 1;
+       if (name)
+               is_of = strncmp(name, "offb", 4);
 
-       options = __fb_get_options(name);
+       enabled = __video_get_options(name, &options, is_of);
 
        if (options) {
                if (!strncmp(options, "off", 3))
-                       retval = 1;
+                       enabled = false;
        }
 
        if (option) {
@@ -85,46 +56,6 @@ int fb_get_options(const char *name, char **option)
                        *option = NULL;
        }
 
-       return retval;
+       return enabled ? 0 : 1; // 0 on success, 1 otherwise
 }
 EXPORT_SYMBOL(fb_get_options);
-
-/**
- *     video_setup - process command line options
- *     @options: string of options
- *
- *     Process command line options for frame buffer subsystem.
- *
- *     NOTE: This function is a __setup and __init function.
- *            It only stores the options.  Drivers have to call
- *            fb_get_options() as necessary.
- */
-static int __init video_setup(char *options)
-{
-       if (!options || !*options)
-               goto out;
-
-       if (!strncmp(options, "ofonly", 6)) {
-               ofonly = 1;
-               goto out;
-       }
-
-       if (strchr(options, ':')) {
-               /* named */
-               int i;
-
-               for (i = 0; i < FB_MAX; i++) {
-                       if (video_options[i] == NULL) {
-                               video_options[i] = options;
-                               break;
-                       }
-               }
-       } else {
-               /* global */
-               fb_mode_option = options;
-       }
-
-out:
-       return 1;
-}
-__setup("video=", video_setup);
diff --git a/include/video/cmdline.h b/include/video/cmdline.h
new file mode 100644 (file)
index 0000000..26b80cd
--- /dev/null
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef VIDEO_CMDLINE_H
+#define VIDEO_CMDLINE_H
+
+#include <linux/types.h>
+
+#if defined(CONFIG_VIDEO_CMDLINE)
+const char *video_get_options(const char *name);
+
+/* exported for compatibility with fbdev; don't use in new code */
+bool __video_get_options(const char *name, const char **option, bool is_of);
+#else
+static inline const char *video_get_options(const char *name)
+{
+       return NULL;
+}
+#endif
+
+#endif