Commit 8714c0ce authored by Steffen Trumtrar's avatar Steffen Trumtrar
Browse files

video: add display_timing and videomode 



Add display_timing structure and the according helper functions. This allows
the description of a display via its supported timing parameters.

Also, add helper functions to convert from display timings to a generic videomode
structure.

The struct display_timing specifies all needed parameters to describe the signal
properties of a display in one mode. This includes
    - ranges for signals that may have min-, max- and typical values
    - single integers for signals that can be on, off or are ignored
    - booleans for signals that are either on or off

As a display may support multiple modes like this, a struct display_timings is
added, that holds all given struct display_timing pointers and declares the
native mode of the display.

Although a display may state that a signal can be in a range, it is driven with
fixed values that indicate a videomode. Therefore graphic drivers don't need all
the information of struct display_timing, but would generate a videomode from
the given set of supported signal timings and work with that.

The video subsystems all define their own structs that describe a mode and work
with that (e.g. fb_videomode or drm_display_mode). To slowly replace all those
various structures and allow code reuse across those subsystems, add struct
videomode as a generic description.

This patch only includes the most basic fields in struct videomode. All missing
fields that are needed to have a really generic video mode description can be
added at a later stage.

Signed-off-by: default avatarSteffen Trumtrar <s.trumtrar@pengutronix.de>
Reviewed-by: default avatarThierry Reding <thierry.reding@avionic-design.de>
Acked-by: default avatarThierry Reding <thierry.reding@avionic-design.de>
Tested-by: default avatarThierry Reding <thierry.reding@avionic-design.de>
Tested-by: default avatarPhilipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: default avatarAfzal Mohammed <Afzal@ti.com>
Tested-by: default avatarRob Clark <robclark@gmail.com>
Tested-by: default avatarLeela Krishna Amudala <leelakrishna.a@gmail.com>
parent ea4f3111

drivers/video/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -33,6 +33,12 @@ config VIDEO_OUTPUT_CONTROL 
	  This framework adds support for low-level control of the video 

	  output switch.



config DISPLAY_TIMING

       bool



config VIDEOMODE

       bool



menuconfig FB

	tristate "Support for frame buffer devices"

	---help---

drivers/video/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -168,3 +168,5 @@ obj-$(CONFIG_FB_VIRTUAL) += vfb.o 


#video output switch sysfs driver

obj-$(CONFIG_VIDEO_OUTPUT_CONTROL) += output.o

obj-$(CONFIG_DISPLAY_TIMING) += display_timing.o

obj-$(CONFIG_VIDEOMODE) += videomode.o

drivers/video/display_timing.c

0 → 100644
+24 −0
Original line number Diff line number Diff line 
/*

 * generic display timing functions

 *

 * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>, Pengutronix

 *

 * This file is released under the GPLv2

 */



#include <linux/export.h>

#include <linux/slab.h>

#include <video/display_timing.h>



void display_timings_release(struct display_timings *disp)

{

	if (disp->timings) {

		unsigned int i;



		for (i = 0; i < disp->num_timings; i++)

			kfree(disp->timings[i]);

		kfree(disp->timings);

	}

	kfree(disp);

}

EXPORT_SYMBOL_GPL(display_timings_release);

drivers/video/videomode.c

0 → 100644
+39 −0
Original line number Diff line number Diff line 
/*

 * generic display timing functions

 *

 * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>, Pengutronix

 *

 * This file is released under the GPLv2

 */



#include <linux/errno.h>

#include <linux/export.h>

#include <video/display_timing.h>

#include <video/videomode.h>



int videomode_from_timing(const struct display_timings *disp,

			  struct videomode *vm, unsigned int index)

{

	struct display_timing *dt;



	dt = display_timings_get(disp, index);

	if (!dt)

		return -EINVAL;



	vm->pixelclock = display_timing_get_value(&dt->pixelclock, TE_TYP);

	vm->hactive = display_timing_get_value(&dt->hactive, TE_TYP);

	vm->hfront_porch = display_timing_get_value(&dt->hfront_porch, TE_TYP);

	vm->hback_porch = display_timing_get_value(&dt->hback_porch, TE_TYP);

	vm->hsync_len = display_timing_get_value(&dt->hsync_len, TE_TYP);



	vm->vactive = display_timing_get_value(&dt->vactive, TE_TYP);

	vm->vfront_porch = display_timing_get_value(&dt->vfront_porch, TE_TYP);

	vm->vback_porch = display_timing_get_value(&dt->vback_porch, TE_TYP);

	vm->vsync_len = display_timing_get_value(&dt->vsync_len, TE_TYP);



	vm->dmt_flags = dt->dmt_flags;

	vm->data_flags = dt->data_flags;



	return 0;

}

EXPORT_SYMBOL_GPL(videomode_from_timing);

include/video/display_timing.h

0 → 100644
+124 −0
Original line number Diff line number Diff line 
/*

 * Copyright 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>

 *

 * description of display timings

 *

 * This file is released under the GPLv2

 */



#ifndef __LINUX_DISPLAY_TIMING_H

#define __LINUX_DISPLAY_TIMING_H



#include <linux/bitops.h>

#include <linux/types.h>



/* VESA display monitor timing parameters */

#define VESA_DMT_HSYNC_LOW		BIT(0)

#define VESA_DMT_HSYNC_HIGH		BIT(1)

#define VESA_DMT_VSYNC_LOW		BIT(2)

#define VESA_DMT_VSYNC_HIGH		BIT(3)



/* display specific flags */

#define DISPLAY_FLAGS_DE_LOW		BIT(0)	/* data enable flag */

#define DISPLAY_FLAGS_DE_HIGH		BIT(1)

#define DISPLAY_FLAGS_PIXDATA_POSEDGE	BIT(2)	/* drive data on pos. edge */

#define DISPLAY_FLAGS_PIXDATA_NEGEDGE	BIT(3)	/* drive data on neg. edge */

#define DISPLAY_FLAGS_INTERLACED	BIT(4)

#define DISPLAY_FLAGS_DOUBLESCAN	BIT(5)



/*

 * A single signal can be specified via a range of minimal and maximal values

 * with a typical value, that lies somewhere inbetween.

 */

struct timing_entry {

	u32 min;

	u32 typ;

	u32 max;

};



enum timing_entry_index {

	TE_MIN = 0,

	TE_TYP = 1,

	TE_MAX = 2,

};



/*

 * Single "mode" entry. This describes one set of signal timings a display can

 * have in one setting. This struct can later be converted to struct videomode

 * (see include/video/videomode.h). As each timing_entry can be defined as a

 * range, one struct display_timing may become multiple struct videomodes.

 *

 * Example: hsync active high, vsync active low

 *

 *				    Active Video

 * Video  ______________________XXXXXXXXXXXXXXXXXXXXXX_____________________

 *	  |<- sync ->|<- back ->|<----- active ----->|<- front ->|<- sync..

 *	  |	     |	 porch  |		     |	 porch	 |

 *

 * HSync _|¯¯¯¯¯¯¯¯¯¯|___________________________________________|¯¯¯¯¯¯¯¯¯

 *

 * VSync ¯|__________|¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯|_________

 */

struct display_timing {

	struct timing_entry pixelclock;



	struct timing_entry hactive;		/* hor. active video */

	struct timing_entry hfront_porch;	/* hor. front porch */

	struct timing_entry hback_porch;	/* hor. back porch */

	struct timing_entry hsync_len;		/* hor. sync len */



	struct timing_entry vactive;		/* ver. active video */

	struct timing_entry vfront_porch;	/* ver. front porch */

	struct timing_entry vback_porch;	/* ver. back porch */

	struct timing_entry vsync_len;		/* ver. sync len */



	unsigned int dmt_flags;			/* VESA DMT flags */

	unsigned int data_flags;		/* video data flags */

};



/*

 * This describes all timing settings a display provides.

 * The native_mode is the default setting for this display.

 * Drivers that can handle multiple videomodes should work with this struct and

 * convert each entry to the desired end result.

 */

struct display_timings {

	unsigned int num_timings;

	unsigned int native_mode;



	struct display_timing **timings;

};



/* get value specified by index from struct timing_entry */

static inline u32 display_timing_get_value(const struct timing_entry *te,

					   enum timing_entry_index index)

{

	switch (index) {

	case TE_MIN:

		return te->min;

		break;

	case TE_TYP:

		return te->typ;

		break;

	case TE_MAX:

		return te->max;

		break;

	default:

		return te->typ;

	}

}



/* get one entry from struct display_timings */

static inline struct display_timing *display_timings_get(const struct

							 display_timings *disp,

							 unsigned int index)

{

	if (disp->num_timings > index)

		return disp->timings[index];

	else

		return NULL;

}



void display_timings_release(struct display_timings *disp);



#endif

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