4be703906c
Benh points out that the msgs[0].flags entry never got initialized, and since it's an automatic stack allocation, it could have any random value, which is bad. Rewrite the initializer to explicitly initialize all fields of the small i2c_msg structure array we generate. Just to keep it all obvious, let's handle msgs[1].buf in the same initializer while we're at it, instead of initializing that one separately later. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
116 lines
2.5 KiB
C
116 lines
2.5 KiB
C
/*
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* driver/vide/fb_ddc.c - DDC/EDID read support.
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*
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* Copyright (C) 2006 Dennis Munsie <dmunsie@cecropia.com>
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file COPYING in the main directory of this archive
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* for more details.
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*/
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#include <linux/delay.h>
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#include <linux/device.h>
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#include <linux/fb.h>
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#include <linux/i2c-algo-bit.h>
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#include "edid.h"
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#define DDC_ADDR 0x50
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static unsigned char *fb_do_probe_ddc_edid(struct i2c_adapter *adapter)
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{
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unsigned char start = 0x0;
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unsigned char *buf = kmalloc(EDID_LENGTH, GFP_KERNEL);
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struct i2c_msg msgs[] = {
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{
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.addr = DDC_ADDR,
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.flags = 0,
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.len = 1,
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.buf = &start,
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}, {
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.addr = DDC_ADDR,
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.flags = I2C_M_RD,
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.len = EDID_LENGTH,
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.buf = buf,
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}
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};
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if (!buf) {
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dev_warn(&adapter->dev, "unable to allocate memory for EDID "
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"block.\n");
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return NULL;
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}
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if (i2c_transfer(adapter, msgs, 2) == 2)
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return buf;
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dev_warn(&adapter->dev, "unable to read EDID block.\n");
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kfree(buf);
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return NULL;
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}
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unsigned char *fb_ddc_read(struct i2c_adapter *adapter)
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{
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struct i2c_algo_bit_data *algo_data = adapter->algo_data;
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unsigned char *edid = NULL;
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int i, j;
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algo_data->setscl(algo_data->data, 1);
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algo_data->setscl(algo_data->data, 0);
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for (i = 0; i < 3; i++) {
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/* For some old monitors we need the
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* following process to initialize/stop DDC
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*/
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algo_data->setsda(algo_data->data, 0);
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msleep(13);
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algo_data->setscl(algo_data->data, 1);
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for (j = 0; j < 5; j++) {
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msleep(10);
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if (algo_data->getscl(algo_data->data))
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break;
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}
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if (j == 5)
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continue;
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algo_data->setsda(algo_data->data, 0);
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msleep(15);
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algo_data->setscl(algo_data->data, 0);
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msleep(15);
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algo_data->setsda(algo_data->data, 1);
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msleep(15);
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/* Do the real work */
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edid = fb_do_probe_ddc_edid(adapter);
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algo_data->setsda(algo_data->data, 0);
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algo_data->setscl(algo_data->data, 0);
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msleep(15);
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algo_data->setscl(algo_data->data, 1);
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for (j = 0; j < 10; j++) {
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msleep(10);
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if (algo_data->getscl(algo_data->data))
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break;
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}
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algo_data->setsda(algo_data->data, 1);
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msleep(15);
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algo_data->setscl(algo_data->data, 0);
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if (edid)
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break;
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}
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/* Release the DDC lines when done or the Apple Cinema HD display
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* will switch off
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*/
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algo_data->setsda(algo_data->data, 0);
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algo_data->setscl(algo_data->data, 0);
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return edid;
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}
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EXPORT_SYMBOL_GPL(fb_ddc_read);
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MODULE_AUTHOR("Dennis Munsie <dmunsie@cecropia.com>");
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MODULE_DESCRIPTION("DDC/EDID reading support");
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MODULE_LICENSE("GPL");
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