Arnd Bergmann 6830733d53 [media] pvrusb2: reduce stack usage pvr2_eeprom_analyze()
The driver uses a relatively large data structure on the stack, which
showed up on my radar as we get a warning with the "latent entropy"
GCC plugin:

drivers/media/usb/pvrusb2/pvrusb2-eeprom.c:153:1: error: the frame size of 1376 bytes is larger than 1152 bytes [-Werror=frame-larger-than=]

The warning is usually hidden as we raise the warning limit to 2048
when the plugin is enabled, but I'd like to lower that again in the
future, and making this function smaller helps to do that without
build regressions.

Further analysis shows that putting an 'i2c_client' structure on
the stack is not really supported, as the embedded 'struct device'
is not initialized here, and we are only saved by the fact that
the function that is called here does not use the pointer at all.

Fixes: d855497edbfb ("V4L/DVB (4228a): pvrusb2 to kernel 2.6.18")

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2017-03-03 07:19:57 -03:00

145 lines
4.1 KiB
C

/*
*
*
* Copyright (C) 2005 Mike Isely <isely@pobox.com>
* Copyright (C) 2004 Aurelien Alleaume <slts@free.fr>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/slab.h>
#include "pvrusb2-eeprom.h"
#include "pvrusb2-hdw-internal.h"
#include "pvrusb2-debug.h"
#define trace_eeprom(...) pvr2_trace(PVR2_TRACE_EEPROM,__VA_ARGS__)
/*
Read and analyze data in the eeprom. Use tveeprom to figure out
the packet structure, since this is another Hauppauge device and
internally it has a family resemblance to ivtv-type devices
*/
#include <media/tveeprom.h>
/* We seem to only be interested in the last 128 bytes of the EEPROM */
#define EEPROM_SIZE 128
/* Grab EEPROM contents, needed for direct method. */
static u8 *pvr2_eeprom_fetch(struct pvr2_hdw *hdw)
{
struct i2c_msg msg[2];
u8 *eeprom;
u8 iadd[2];
u8 addr;
u16 eepromSize;
unsigned int offs;
int ret;
int mode16 = 0;
unsigned pcnt,tcnt;
eeprom = kmalloc(EEPROM_SIZE,GFP_KERNEL);
if (!eeprom) {
pvr2_trace(PVR2_TRACE_ERROR_LEGS,
"Failed to allocate memory required to read eeprom");
return NULL;
}
trace_eeprom("Value for eeprom addr from controller was 0x%x",
hdw->eeprom_addr);
addr = hdw->eeprom_addr;
/* Seems that if the high bit is set, then the *real* eeprom
address is shifted right now bit position (noticed this in
newer PVR USB2 hardware) */
if (addr & 0x80) addr >>= 1;
/* FX2 documentation states that a 16bit-addressed eeprom is
expected if the I2C address is an odd number (yeah, this is
strange but it's what they do) */
mode16 = (addr & 1);
eepromSize = (mode16 ? 4096 : 256);
trace_eeprom("Examining %d byte eeprom at location 0x%x using %d bit addressing",
eepromSize, addr,
mode16 ? 16 : 8);
msg[0].addr = addr;
msg[0].flags = 0;
msg[0].len = mode16 ? 2 : 1;
msg[0].buf = iadd;
msg[1].addr = addr;
msg[1].flags = I2C_M_RD;
/* We have to do the actual eeprom data fetch ourselves, because
(1) we're only fetching part of the eeprom, and (2) if we were
getting the whole thing our I2C driver can't grab it in one
pass - which is what tveeprom is otherwise going to attempt */
memset(eeprom,0,EEPROM_SIZE);
for (tcnt = 0; tcnt < EEPROM_SIZE; tcnt += pcnt) {
pcnt = 16;
if (pcnt + tcnt > EEPROM_SIZE) pcnt = EEPROM_SIZE-tcnt;
offs = tcnt + (eepromSize - EEPROM_SIZE);
if (mode16) {
iadd[0] = offs >> 8;
iadd[1] = offs;
} else {
iadd[0] = offs;
}
msg[1].len = pcnt;
msg[1].buf = eeprom+tcnt;
if ((ret = i2c_transfer(&hdw->i2c_adap,
msg,ARRAY_SIZE(msg))) != 2) {
pvr2_trace(PVR2_TRACE_ERROR_LEGS,
"eeprom fetch set offs err=%d",ret);
kfree(eeprom);
return NULL;
}
}
return eeprom;
}
/* Directly call eeprom analysis function within tveeprom. */
int pvr2_eeprom_analyze(struct pvr2_hdw *hdw)
{
u8 *eeprom;
struct tveeprom tvdata;
memset(&tvdata,0,sizeof(tvdata));
eeprom = pvr2_eeprom_fetch(hdw);
if (!eeprom)
return -EINVAL;
tveeprom_hauppauge_analog(NULL, &tvdata, eeprom);
trace_eeprom("eeprom assumed v4l tveeprom module");
trace_eeprom("eeprom direct call results:");
trace_eeprom("has_radio=%d",tvdata.has_radio);
trace_eeprom("tuner_type=%d",tvdata.tuner_type);
trace_eeprom("tuner_formats=0x%x",tvdata.tuner_formats);
trace_eeprom("audio_processor=%d",tvdata.audio_processor);
trace_eeprom("model=%d",tvdata.model);
trace_eeprom("revision=%d",tvdata.revision);
trace_eeprom("serial_number=%d",tvdata.serial_number);
trace_eeprom("rev_str=%s",tvdata.rev_str);
hdw->tuner_type = tvdata.tuner_type;
hdw->tuner_updated = !0;
hdw->serial_number = tvdata.serial_number;
hdw->std_mask_eeprom = tvdata.tuner_formats;
kfree(eeprom);
return 0;
}