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Commit fc5891c8 authored by Dennis Munsie's avatar Dennis Munsie Committed by Linus Torvalds
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[PATCH] fbdev: Add generic ddc read functionality 



Adds functionality to read the EDID information over the DDC bus in a generic
way.  This code is based on the DDC implementation in the radeon driver.

[adaplas]
- separate from fbmon.c and place in new file fb_ddc.c
- remove dependency to CONFIG_I2C and CONFIG_I2C_ALGOBIT, otherwise, feature
  will not compile if i2c support is compiled as a module
- feature is selectable only by drivers needing it. It must have a
  'select FB_DDC if xxx' in Kconfig
- change printk's to dev_*, the i2c people prefers it

Signed-off-by: default avatarDennis Munsie <dmunsie@cecropia.com>
Signed-off-by: default avatarAntonino Daplas <adaplas@pol.net>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 66cf7512

drivers/video/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -53,6 +53,11 @@ config FB 
	  (e.g. an accelerated X server) and that are not frame buffer

	  device-aware may cause unexpected results. If unsure, say N.



config FB_DDC

       tristate

       depends on FB && I2C && I2C_ALGOBIT

       default n



config FB_CFB_FILLRECT

	tristate

	depends on FB

drivers/video/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ obj-$(CONFIG_FB_CFB_FILLRECT) += cfbfillrect.o 
obj-$(CONFIG_FB_CFB_COPYAREA)  += cfbcopyarea.o

obj-$(CONFIG_FB_CFB_IMAGEBLIT) += cfbimgblt.o

obj-$(CONFIG_FB_MACMODES)      += macmodes.o

obj-$(CONFIG_FB_DDC)           += fb_ddc.o



# Hardware specific drivers go first

obj-$(CONFIG_FB_RETINAZ3)         += retz3fb.o

drivers/video/fb_ddc.c

0 → 100644
+116 −0
Original line number Diff line number Diff line 
/*

 * driver/vide/fb_ddc.c - DDC/EDID read support.

 *

 *  Copyright (C) 2006 Dennis Munsie <dmunsie@cecropia.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.

 */



#include <linux/delay.h>

#include <linux/device.h>

#include <linux/fb.h>

#include <linux/i2c-algo-bit.h>



#include "edid.h"



#define DDC_ADDR	0x50



static unsigned char *fb_do_probe_ddc_edid(struct i2c_adapter *adapter)

{

	unsigned char start = 0x0;

	struct i2c_msg msgs[] = {

		{

			.addr	= DDC_ADDR,

			.len	= 1,

			.buf	= &start,

		}, {

			.addr	= DDC_ADDR,

			.flags	= I2C_M_RD,

			.len	= EDID_LENGTH,

		}

	};

	unsigned char *buf;



	buf = kmalloc(EDID_LENGTH, GFP_KERNEL);

	if (!buf) {

		dev_warn(&adapter->dev, "unable to allocate memory for EDID "

			 "block.\n");

		return NULL;

	}

	msgs[1].buf = buf;



	if (i2c_transfer(adapter, msgs, 2) == 2)

		return buf;



	dev_warn(&adapter->dev, "unable to read EDID block.\n");

	kfree(buf);

	return NULL;

}



unsigned char *fb_ddc_read(struct i2c_adapter *adapter)

{

	struct i2c_algo_bit_data *algo_data = adapter->algo_data;

	unsigned char *edid = NULL;

	int i, j;



	algo_data->setscl(algo_data->data, 1);

	algo_data->setscl(algo_data->data, 0);



	for (i = 0; i < 3; i++) {

		/* For some old monitors we need the

		 * following process to initialize/stop DDC

		 */

		algo_data->setsda(algo_data->data, 0);

		msleep(13);



		algo_data->setscl(algo_data->data, 1);

		for (j = 0; j < 5; j++) {

			msleep(10);

			if (algo_data->getscl(algo_data->data))

				break;

		}

		if (j == 5)

			continue;



		algo_data->setsda(algo_data->data, 0);

		msleep(15);

		algo_data->setscl(algo_data->data, 0);

		msleep(15);

		algo_data->setsda(algo_data->data, 1);

		msleep(15);



		/* Do the real work */

		edid = fb_do_probe_ddc_edid(adapter);

		algo_data->setsda(algo_data->data, 0);

		algo_data->setscl(algo_data->data, 0);

		msleep(15);



		algo_data->setscl(algo_data->data, 1);

		for (j = 0; j < 10; j++) {

			msleep(10);

			if (algo_data->getscl(algo_data->data))

				break;

		}



		algo_data->setsda(algo_data->data, 1);

		msleep(15);

		algo_data->setscl(algo_data->data, 0);

		if (edid)

			break;

	}

	/* Release the DDC lines when done or the Apple Cinema HD display

	 * will switch off

	 */

	algo_data->setsda(algo_data->data, 0);

	algo_data->setscl(algo_data->data, 0);



	return edid;

}



EXPORT_SYMBOL_GPL(fb_ddc_read);



MODULE_AUTHOR("Dennis Munsie <dmunsie@cecropia.com>");

MODULE_DESCRIPTION("DDC/EDID reading support");

MODULE_LICENSE("GPL");

include/linux/fb.h

+2 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
#define _LINUX_FB_H



#include <asm/types.h>

#include <linux/i2c.h>



/* Definitions of frame buffers						*/
@@ -940,6 +941,7 @@ extern void fb_edid_to_monspecs(unsigned char *edid, 
				struct fb_monspecs *specs);

extern void fb_destroy_modedb(struct fb_videomode *modedb);

extern int fb_find_mode_cvt(struct fb_videomode *mode, int margins, int rb);

extern unsigned char *fb_ddc_read(struct i2c_adapter *adapter);



/* drivers/video/modedb.c */

#define VESA_MODEDB_SIZE 34