Re: [PATCH] soc_camera: match signedness of soc_camera_limit_side()

["Németh Márton" <nm127@freemail.hu>]

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Guennadi Liakhovetski wrote:
> On Sat, 23 Jan 2010, Németh Márton wrote:
> 
>> From: Márton Németh <nm127@freemail.hu>
>>
>> The parameters of soc_camera_limit_side() are either a pointer to
>> a structure element from v4l2_rect, or constants. The structure elements
>> of the v4l2_rect are signed (see <linux/videodev2.h>) so do the computations
>> also with signed values.
>>
>> This will remove the following sparse warning (see "make C=1"):
>>  * incorrect type in argument 1 (different signedness)
>>        expected unsigned int *start
>>        got signed int *<noident>
> 
> Well, it is interesting, but insufficient. And, unfortunately, I don't 
> have a good (and easy) recipe for how to fix this properly.
> 
> The problem is, that in soc_camera_limit_side all tests and arithmetics 
> are performed with unsigned in mind, now, if you change them to signed, 
> think what happens, if some of them are negative. No, I don't know when 
> negative members of struct v4l2_rect make sense, having them signed 
> doesn't seem a very good idea to me. But they cannot be changed - that's a 
> part of the user-space API...
> 
> Casting all parameters inside that inline to unsigned would be way too 
> ugly. Maybe we could at least keep start_min, length_min, and length_max 
> unsigned, and only change start and length to signed, and only cast those 
> two inside the function. Then, if you grep through all the drivers, 
> there's only one location, where soc_camera_limit_side() is called with 
> the latter 3 parameters not constant - two calls in 
> sh_mobile_ceu_camera.c. So, to keep sparse happy, you'd have to cast 
> there. Ideally, you would also add checks there for negative values...

I'll have a look to see what can be done to handle the negative values properly.

>> Signed-off-by: Márton Németh <nm127@freemail.hu>
>> ---
>> diff -r 2a50a0a1c951 linux/include/media/soc_camera.h
>> --- a/linux/include/media/soc_camera.h	Sat Jan 23 00:14:32 2010 -0200
>> +++ b/linux/include/media/soc_camera.h	Sat Jan 23 10:09:41 2010 +0100
>> @@ -264,9 +264,8 @@
>>  		common_flags;
>>  }
>>
>> -static inline void soc_camera_limit_side(unsigned int *start,
>> -		unsigned int *length, unsigned int start_min,
>> -		unsigned int length_min, unsigned int length_max)
>> +static inline void soc_camera_limit_side(int *start, int *length,
>> +		int start_min, int length_min, int length_max)
>>  {
>>  	if (*length < length_min)
>>  		*length = length_min;
>> diff -r 2a50a0a1c951 linux/drivers/media/video/rj54n1cb0c.c
>> --- a/linux/drivers/media/video/rj54n1cb0c.c	Sat Jan 23 00:14:32 2010 -0200
>> +++ b/linux/drivers/media/video/rj54n1cb0c.c	Sat Jan 23 10:09:41 2010 +0100
>> @@ -555,15 +555,15 @@
>>  	return ret;
>>  }
>>
>> -static int rj54n1_sensor_scale(struct v4l2_subdev *sd, u32 *in_w, u32 *in_h,
>> -			       u32 *out_w, u32 *out_h);
>> +static int rj54n1_sensor_scale(struct v4l2_subdev *sd, s32 *in_w, s32 *in_h,
>> +			       s32 *out_w, s32 *out_h);
>>
>>  static int rj54n1_s_crop(struct v4l2_subdev *sd, struct v4l2_crop *a)
>>  {
>>  	struct i2c_client *client = sd->priv;
>>  	struct rj54n1 *rj54n1 = to_rj54n1(client);
>>  	struct v4l2_rect *rect = &a->c;
>> -	unsigned int dummy = 0, output_w, output_h,
>> +	int dummy = 0, output_w, output_h,
>>  		input_w = rect->width, input_h = rect->height;
>>  	int ret;
> 
> And these:
> 
> 	if (output_w > max(512U, input_w / 2)) {
> 	if (output_h > max(384U, input_h / 2)) {
> 
> would now produce compiler warnings... Have you actually tried to compile 
> your patch? You'll also have to change formats in dev_dbg() calls here...

Interesting to hear about compiler warnings. I don't get them if I apply the patch
on top of version 14064:31eaa9423f98 of http://linuxtv.org/hg/v4l-dvb/  . What
is your compiler version?

I used the attached configuration. Maybe some other options has to be
turned on?

localhost:/usr/src/linuxtv.org/v4l-dvb$ patch -p1 <../soc_camera_signedness.patch
patching file linux/include/media/soc_camera.h
patching file linux/drivers/media/video/rj54n1cb0c.c
localhost:/usr/src/linuxtv.org/v4l-dvb$ make C=1 2>&1 |tee result1.txt
make -C /usr/src/linuxtv.org/v4l-dvb/v4l
make[1]: Entering directory `/usr/src/linuxtv.org/v4l-dvb/v4l'
creating symbolic links...
make -C firmware prep
make[2]: Entering directory `/usr/src/linuxtv.org/v4l-dvb/v4l/firmware'
make[2]: Leaving directory `/usr/src/linuxtv.org/v4l-dvb/v4l/firmware'
make -C firmware
make[2]: Entering directory `/usr/src/linuxtv.org/v4l-dvb/v4l/firmware'
make[2]: Nothing to be done for `default'.
make[2]: Leaving directory `/usr/src/linuxtv.org/v4l-dvb/v4l/firmware'
Kernel build directory is /lib/modules/2.6.33-rc4/build
make -C /lib/modules/2.6.33-rc4/build SUBDIRS=/usr/src/linuxtv.org/v4l-dvb/v4l  modules
make[2]: Entering directory `/usr/src/linuxtv.org/pinchartl/uvcvideo/v4l-dvb'
  CHECK   /usr/src/linuxtv.org/v4l-dvb/v4l/mt9m001.c
  CC [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/mt9m001.o
  CHECK   /usr/src/linuxtv.org/v4l-dvb/v4l/mt9m111.c
  CC [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/mt9m111.o
  CHECK   /usr/src/linuxtv.org/v4l-dvb/v4l/mt9t031.c
  CC [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/mt9t031.o
  CHECK   /usr/src/linuxtv.org/v4l-dvb/v4l/mt9t112.c
  CC [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/mt9t112.o
  CHECK   /usr/src/linuxtv.org/v4l-dvb/v4l/mt9v022.c
  CC [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/mt9v022.o
  CHECK   /usr/src/linuxtv.org/v4l-dvb/v4l/ov772x.c
  CC [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/ov772x.o
  CHECK   /usr/src/linuxtv.org/v4l-dvb/v4l/ov9640.c
  CC [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/ov9640.o
  CHECK   /usr/src/linuxtv.org/v4l-dvb/v4l/rj54n1cb0c.c
  CC [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/rj54n1cb0c.o
  CHECK   /usr/src/linuxtv.org/v4l-dvb/v4l/tw9910.c
  CC [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/tw9910.o
  CHECK   /usr/src/linuxtv.org/v4l-dvb/v4l/soc_camera.c
  CC [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/soc_camera.o
  CHECK   /usr/src/linuxtv.org/v4l-dvb/v4l/soc_camera_platform.c
  CC [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/soc_camera_platform.o
  Building modules, stage 2.
  MODPOST 28 modules
  LD [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/mt9m001.ko
  LD [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/mt9m111.ko
  LD [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/mt9t031.ko
  LD [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/mt9t112.ko
  LD [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/mt9v022.ko
  LD [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/ov772x.ko
  LD [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/ov9640.ko
  LD [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/rj54n1cb0c.ko
  LD [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/soc_camera.ko
  LD [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/soc_camera_platform.ko
  LD [M]  /usr/src/linuxtv.org/v4l-dvb/v4l/tw9910.ko
make[2]: Leaving directory `/usr/src/linuxtv.org/pinchartl/uvcvideo/v4l-dvb'
./scripts/rmmod.pl check
found 28 modules
make[1]: Leaving directory `/usr/src/linuxtv.org/v4l-dvb/v4l'
nmarci@asus-eeepc:/usr/src/linuxtv.org/v4l-dvb$ gcc --version
gcc (Debian 4.3.4-6) 4.3.4
Copyright (C) 2008 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

> 
>> @@ -638,8 +638,8 @@
>>   * the output one, updates the window sizes and returns an error or the resize
>>   * coefficient on success. Note: we only use the "Fixed Scaling" on this camera.
>>   */
>> -static int rj54n1_sensor_scale(struct v4l2_subdev *sd, u32 *in_w, u32 *in_h,
>> -			       u32 *out_w, u32 *out_h)
>> +static int rj54n1_sensor_scale(struct v4l2_subdev *sd, s32 *in_w, s32 *in_h,
>> +			       s32 *out_w, s32 *out_h)
>>  {
>>  	struct i2c_client *client = sd->priv;
>>  	struct rj54n1 *rj54n1 = to_rj54n1(client);
>> @@ -1017,7 +1017,7 @@
>>  	struct i2c_client *client = sd->priv;
>>  	struct rj54n1 *rj54n1 = to_rj54n1(client);
>>  	const struct rj54n1_datafmt *fmt;
>> -	unsigned int output_w, output_h, max_w, max_h,
>> +	int output_w, output_h, max_w, max_h,
>>  		input_w = rj54n1->rect.width, input_h = rj54n1->rect.height;
>>  	int ret;
> 
> and here.
> 
> Thanks
> Guennadi
> ---
> Guennadi Liakhovetski, Ph.D.
> Freelance Open-Source Software Developer
> http://www.open-technology.de/
> 
> 

Regards,

	Márton Németh

[-- Attachment #2: .config --]
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#
# Automatically generated make config: don't edit
# Linux kernel version: KERNELVERSION
# Wed Jan 27 18:58:24 2010
#
# CONFIG_SND_MIRO is not set
CONFIG_INPUT=y
CONFIG_USB=m
CONFIG_FW_LOADER=y
# CONFIG_SPARC64 is not set
# CONFIG_PLAT_M32700UT is not set
# CONFIG_SND_FM801 is not set
CONFIG_FB_CFB_IMAGEBLIT=y
# CONFIG_GPIO_PCA953X is not set
# CONFIG_HAVE_CLK is not set
# CONFIG_FIQ is not set
CONFIG_SND=m
# CONFIG_MT9M001_PCA9536_SWITCH is not set
# CONFIG_ARCH_OMAP2 is not set
# CONFIG_SPARC32 is not set
CONFIG_I2C_ALGOBIT=m
# CONFIG_SND_ISA is not set
CONFIG_INET=y
CONFIG_CRC32=y
CONFIG_SYSFS=y
CONFIG_MMC=m
CONFIG_ISA=y
CONFIG_PCI=y
CONFIG_PARPORT_1284=y
CONFIG_FB_CFB_FILLRECT=y
# CONFIG_MT9V022_PCA9536_SWITCH is not set
CONFIG_VIRT_TO_BUS=y
CONFIG_PARPORT=m
# CONFIG_ARCH_DAVINCI_DM644x is not set
# CONFIG_FIREWIRE is not set
CONFIG_NET=y
# CONFIG_ARCH_DAVINCI is not set
CONFIG_FB_CFB_COPYAREA=y
# CONFIG_PXA27x is not set
# CONFIG_SGI_IP22 is not set
CONFIG_I2C=m
# CONFIG_ARCH_DAVINCI_DM355 is not set
CONFIG_MODULES=y
# CONFIG_TUNER_XC2028 is not set
CONFIG_HAS_IOMEM=y
# CONFIG_MACH_DAVINCI_DM6467_EVM is not set
CONFIG_HAS_DMA=y
CONFIG_FB=y
# CONFIG_ARCH_MX1 is not set
# CONFIG_SONY_LAPTOP is not set
# CONFIG_MX3_IPU is not set
CONFIG_SND_PCM=m
CONFIG_EXPERIMENTAL=y
# CONFIG_M32R is not set
# CONFIG_IEEE1394 is not set
# CONFIG_VIDEO_KERNEL_VERSION is not set
CONFIG_MEDIA_SUPPORT=m

#
# Multimedia core support
#
CONFIG_VIDEO_DEV=m
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# CONFIG_VIDEO_ALLOW_V4L1 is not set
# CONFIG_VIDEO_V4L1_COMPAT is not set
# CONFIG_DVB_CORE is not set
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#
# Multimedia drivers
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CONFIG_MEDIA_TUNER_TDA8290=m
CONFIG_MEDIA_TUNER_TDA9887=m
CONFIG_MEDIA_TUNER_TEA5761=m
CONFIG_MEDIA_TUNER_TEA5767=m
CONFIG_MEDIA_TUNER_MT20XX=m
CONFIG_MEDIA_TUNER_XC2028=m
CONFIG_MEDIA_TUNER_XC5000=m
CONFIG_MEDIA_TUNER_MC44S803=m
CONFIG_VIDEO_V4L2=m
CONFIG_VIDEOBUF_GEN=m
CONFIG_VIDEO_CAPTURE_DRIVERS=y
# CONFIG_VIDEO_ADV_DEBUG is not set
# CONFIG_VIDEO_FIXED_MINOR_RANGES is not set
# CONFIG_VIDEO_HELPER_CHIPS_AUTO is not set
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#
# Encoders/decoders and other helper chips
#

#
# Audio decoders
#
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# CONFIG_VIDEO_TDA9875 is not set
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# CONFIG_VIDEO_TEA6420 is not set
# CONFIG_VIDEO_MSP3400 is not set
# CONFIG_VIDEO_CS5345 is not set
# CONFIG_VIDEO_CS53L32A is not set
# CONFIG_VIDEO_M52790 is not set
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# CONFIG_VIDEO_WM8775 is not set
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#
# RDS decoders
#
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#
# Video decoders
#
# CONFIG_VIDEO_ADV7180 is not set
# CONFIG_VIDEO_BT819 is not set
# CONFIG_VIDEO_BT856 is not set
# CONFIG_VIDEO_BT866 is not set
# CONFIG_VIDEO_KS0127 is not set
# CONFIG_VIDEO_OV7670 is not set
# CONFIG_VIDEO_MT9V011 is not set
# CONFIG_VIDEO_TCM825X is not set
# CONFIG_VIDEO_SAA7110 is not set
# CONFIG_VIDEO_SAA711X is not set
# CONFIG_VIDEO_SAA717X is not set
# CONFIG_VIDEO_TVP514X is not set
# CONFIG_VIDEO_TVP5150 is not set
# CONFIG_VIDEO_VPX3220 is not set

#
# Video and audio decoders
#
# CONFIG_VIDEO_CX25840 is not set

#
# MPEG video encoders
#
# CONFIG_VIDEO_CX2341X is not set

#
# Video encoders
#
# CONFIG_VIDEO_SAA7127 is not set
# CONFIG_VIDEO_SAA7185 is not set
# CONFIG_VIDEO_ADV7170 is not set
# CONFIG_VIDEO_ADV7175 is not set
# CONFIG_VIDEO_THS7303 is not set
# CONFIG_VIDEO_ADV7343 is not set

#
# Video improvement chips
#
# CONFIG_VIDEO_UPD64031A is not set
# CONFIG_VIDEO_UPD64083 is not set
# CONFIG_VIDEO_VIVI is not set
# CONFIG_VIDEO_BT848 is not set
# CONFIG_VIDEO_PMS is not set
# CONFIG_VIDEO_SAA5246A is not set
# CONFIG_VIDEO_SAA5249 is not set
# CONFIG_VIDEO_ZORAN is not set
# CONFIG_VIDEO_SAA7134 is not set
# CONFIG_VIDEO_HEXIUM_ORION is not set
# CONFIG_VIDEO_HEXIUM_GEMINI is not set
# CONFIG_VIDEO_CX88 is not set
# CONFIG_VIDEO_IVTV is not set
# CONFIG_VIDEO_CAFE_CCIC is not set
CONFIG_SOC_CAMERA=m
CONFIG_SOC_CAMERA_MT9M001=m
CONFIG_SOC_CAMERA_MT9M111=m
CONFIG_SOC_CAMERA_MT9T031=m
CONFIG_SOC_CAMERA_MT9T112=m
CONFIG_SOC_CAMERA_MT9V022=m
CONFIG_SOC_CAMERA_RJ54N1=m
CONFIG_SOC_CAMERA_TW9910=m
CONFIG_SOC_CAMERA_PLATFORM=m
CONFIG_SOC_CAMERA_OV772X=m
CONFIG_SOC_CAMERA_OV9640=m
# CONFIG_V4L_USB_DRIVERS is not set
# CONFIG_RADIO_ADAPTERS is not set
# CONFIG_DAB is not set

#
# Audio devices for multimedia
#

#
# ALSA sound
#
# CONFIG_SND_BT87X is not set
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