Commit 93604a5a authored by Thomas Zimmermann's avatar Thomas Zimmermann
Browse files

fbdev: Handle video= parameter in video/cmdline.c 



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: default avatarThomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: default avatarJavier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230209135509.7786-9-tzimmermann@suse.de
parent 36722179

drivers/gpu/drm/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -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)

drivers/video/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -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

drivers/video/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

drivers/video/cmdline.c

0 → 100644
+133 −0
Original line number Diff line number Diff line 
// 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);

drivers/video/fbdev/Kconfig

+1 −4
Original line number Diff line number Diff line
@@ -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