port-arm/48855: i2cscan on RPi NetBSD build finds device for all addresses

[yunixx%gmail.com@localhost]

>Number:         48855
>Category:       port-arm
>Synopsis:       i2cscan on RPi NetBSD build finds device for all addresses
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    port-arm-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri May 30 21:05:00 +0000 2014
>Originator:     Yunis Mustafa
>Release:        evbarm-earmhf 201405181900Z
>Organization:
>Environment:
NetBSD rpi 6.99.42 NetBSD 6.99.42 (RPI) #0: Sun May 18 20:34:46 UTC 2014  
builds%b44.netbsd.org@localhost:/home/builds/ab/HEAD/evbarm-earmhf/201405181900Z-obj/home/builds/ab/HEAD/src/sys/arch/evbarm/compile/RPI
 evbarm
>Description:
i2cscan /dev/iic0 (or iic1) erroneously detects devices and prints out the 
following for pretty much every address:

/dev/iic0: found device at 0x09
/dev/iic0: found device at 0x0a
/dev/iic0: found device at 0x0b
/dev/iic0: found device at 0x0d
/dev/iic0: found device at 0x0e
/dev/iic0: found device at 0x0f
/dev/iic0: found device at 0x10
/dev/iic0: found device at 0x11
/dev/iic0: found device at 0x12
/dev/iic0: found device at 0x13
/dev/iic0: found device at 0x14
/dev/iic0: found device at 0x15
/dev/iic0: found device at 0x16
/dev/iic0: found device at 0x17
/dev/iic0: found device at 0x18
/dev/iic0: found device at 0x19
/dev/iic0: found device at 0x1a
/dev/iic0: found device at 0x1b
/dev/iic0: found device at 0x1c
/dev/iic0: found device at 0x1d
/dev/iic0: found device at 0x1e
/dev/iic0: found device at 0x1f
/dev/iic0: found device at 0x20
/dev/iic0: found device at 0x21
/dev/iic0: found device at 0x22
/dev/iic0: found device at 0x23
/dev/iic0: found device at 0x24
/dev/iic0: found device at 0x25
/dev/iic0: found device at 0x26
/dev/iic0: found device at 0x27
/dev/iic0: found device at 0x29
/dev/iic0: found device at 0x2a
/dev/iic0: found device at 0x2b
/dev/iic0: found device at 0x2c
/dev/iic0: found device at 0x2d
/dev/iic0: found device at 0x2e
/dev/iic0: found device at 0x2f
/dev/iic0: found device at 0x38
/dev/iic0: found device at 0x39
/dev/iic0: found device at 0x3a
/dev/iic0: found device at 0x3b
/dev/iic0: found device at 0x3c
/dev/iic0: found device at 0x3d
/dev/iic0: found device at 0x3e
/dev/iic0: found device at 0x3f
/dev/iic0: found device at 0x40
/dev/iic0: found device at 0x41
/dev/iic0: found device at 0x42
/dev/iic0: found device at 0x43
/dev/iic0: found device at 0x44
/dev/iic0: found device at 0x45
/dev/iic0: found device at 0x46
/dev/iic0: found device at 0x47
/dev/iic0: found device at 0x4c
/dev/iic0: found device at 0x4d
/dev/iic0: found device at 0x4e
/dev/iic0: found device at 0x4f
/dev/iic0: found device at 0x60
/dev/iic0: found device at 0x62
/dev/iic0: found device at 0x63
/dev/iic0: found device at 0x64
/dev/iic0: found device at 0x65
/dev/iic0: found device at 0x66
/dev/iic0: found device at 0x67
/dev/iic0: found device at 0x68
/dev/iic0: found device at 0x69
/dev/iic0: found device at 0x6a
/dev/iic0: found device at 0x6b
/dev/iic0: found device at 0x6c
/dev/iic0: found device at 0x6d
/dev/iic0: found device at 0x6e
/dev/iic0: found device at 0x6f
/dev/iic0: found device at 0x70
/dev/iic0: found device at 0x71
/dev/iic0: found device at 0x72
/dev/iic0: found device at 0x73
/dev/iic0: found device at 0x74
/dev/iic0: found device at 0x75
/dev/iic0: found device at 0x76
/dev/iic0: found device at 0x77
/dev/iic0: 80 devices found
>How-To-Repeat:
i2cscan /dev/iic0

on a Raspberry Pi
>Fix:
On further debugging, it seems that the iic_smbus_quick_write() used by 
i2cscan.c to detect the devices returns success erroneously for some reason. 

If iic_smbus_receive_byte() is used instead to detect the devices, it correctly 
detects only the actual devices connected to the i2c bus (at least in my 
testing with an i2c device with address 0x11)