On Mon, Aug 17, 2015 at 4:56 PM, Gerard Bucas <[email protected]> wrote: > Hi Bill > > Thanks for your fast response! > > You are right of course BUT why does one need the "Synopsis Designware I2c > adapter"!? As I don't really know what it is, I assume I don't need it!! > > The fact that Ubuntu includes it, of course explains why it shows those extra > two buses in ubuntu. So that answers my first question! > How about my 2nd queston? BOTH yocto and Ubuntu show the same i2c devices > detected on the "5th i2c bus (# 4 in yocto and #6 in Ubuntu which makes sense > when one compensates for the two Designware buses detected)? > > Including my questions again below, so you don't have to go and search for it. > > I have two questions: > > 1. Where does i2cdetect get the "i2c adapter" bus names? How can they be > different with same firmware & hardware & linux kernel (between yocto & > Ubuntu)? Is this from some firmware or OS config? OK - explained by the fact > that Ubuntu includes two "Synopsis Designware" i2c buses. >
The i2c adapter bus names are directly from the Linux driver for the bus. For example, "Synopsys DesignWare I2C adapter" comes from: ../drivers/i2c/busses/i2c-designware-platdrv.c > 2. Why are all those i2c devices detected by BOTH yocto linux and Ubuntu!? > Where do they come from? Is this due to some firmware or OS config? They are detected because both kernels are configured to support i2c. So yes, it is a function of the OS configuration. "i2cdetect is a userspace program to scan an I2C bus for devices. It outputs a table with the list of detected devices on the specified bus." You are asking i2cdetect to list all of the devices on the i2cbus because you're not supplying a specific bus as a parameter. See man i2cdetect for more info. I hope that helps. If you're interested in i2c support in the linux kernel, see the documentation in the source: https://www.kernel.org/doc/Documentation/i2c/ > > Below are the i2cdetect outputs from both my yocto and Ubuntu OS's (NOTE: > both are using the linux 3.19 kernel): > > YOCTO: > # uname -a > Linux intel-corei7-64 3.19.5-yocto-standard #1 SMP PREEMPT Fri Aug 14 > 00:21:30 UTC 2015 x86_64 GNU/Linux > > #modprobe i2c-dev > #i2cdetect -l > i2c-0 i2c i915 gmbus ssc I2C adapter > i2c-1 i2c i915 gmbus vga I2C adapter > i2c-2 i2c i915 gmbus panel I2C adapter > i2c-3 i2c i915 gmbus dpc I2C adapter > i2c-4 i2c i915 gmbus dpb I2C adapter > i2c-5 i2c i915 gmbus dpd I2C adapter > i2c-6 i2c DPDDC-B I2C adapter > > #i2cdetect -y 4 > 0 1 2 3 4 5 6 7 8 9 a b c d e f > 00: -- -- -- -- -- -- -- -- -- -- -- -- -- > 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > 30: 30 -- -- -- -- -- -- 37 -- -- 3a -- -- -- -- -- > 40: -- -- -- -- -- -- -- -- -- -- 4a 4b -- -- -- -- > 50: 50 51 52 53 54 55 56 57 -- -- -- -- -- -- -- -- > 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > 70: -- -- -- -- -- -- -- -- > > UBUNTU: > # uname -a > Linux tekmagic 3.19.0-26-generic #28~14.04.1-Ubuntu SMP Wed Aug 12 14:09:17 > UTC 2015 x86_64 x86_64 x86_64 GNU/Linux > > # modprobe i2c-dev > > # i2cdetect -l > i2c-0 i2c Synopsys DesignWare I2C adapter I2C adapter > i2c-1 i2c Synopsys DesignWare I2C adapter I2C adapter > i2c-2 i2c i915 gmbus ssc I2C adapter > i2c-3 i2c i915 gmbus vga I2C adapter > i2c-4 i2c i915 gmbus panel I2C adapter > i2c-5 i2c i915 gmbus dpc I2C adapter > i2c-6 i2c i915 gmbus dpb I2C adapter > i2c-7 i2c i915 gmbus dpd I2C adapter > i2c-8 i2c DPDDC-B I2C adapter > > # i2cdetect -y 6 > 0 1 2 3 4 5 6 7 8 9 a b c d e f > 00: -- -- -- -- -- -- -- -- -- -- -- -- -- > 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > 30: 30 -- -- -- -- -- -- 37 -- -- 3a -- -- -- -- -- > 40: -- -- -- -- -- -- -- -- -- -- 4a 4b -- -- -- -- > 50: 50 51 52 53 54 55 56 57 -- -- -- -- -- -- -- -- > 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > 70: -- -- -- -- -- -- -- -- > > Thanks!! > > Gerard > > > -----Original Message----- > From: Bill Traynor [mailto:[email protected]] > Sent: Monday, August 17, 2015 4:38 PM > To: [email protected]; MinnowBoard Development and Community Discussion > <[email protected]> > Subject: Re: [MinnowBoard] [edk2] i2cdetect inconsistency/problem > > Are you using identical kernel configurations for each build? > > It looks to me like you may not have configured for the Synopsys DesignWare > I2C adapter in the Yocto build. > > > On Mon, Aug 17, 2015 at 4:30 PM, Gerard Bucas <[email protected]> wrote: >> Synopsys DesignWare I2C adapter > _______________________________________________ elinux-MinnowBoard mailing list [email protected] http://lists.elinux.org/mailman/listinfo/elinux-minnowboard
