From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michal Zatloukal" Subject: Re: Can't read DIMM SPD info (DDR2) Date: Sun, 11 Sep 2011 11:50:09 +0200 Message-ID: References: <20110911100945.73fffa6a@endymion.delvare> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20110911100945.73fffa6a-R0o5gVi9kd7kN2dkZ6Wm7A@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-i2c@vger.kernel.org On Sun, 11 Sep 2011 10:09:45 +0200, Jean Delvare wrote: > Hi Michal, > ... > Second preliminary note: as far as I know, memtest86 reads SPD > information using a BIOS call, while decode-dimms gets the information > over the SMBus, assuming that SPD EEPROMs are connected to the SMBus > and reachable at run time. This difference in access methods can > explain why memtest86 can see information and decode-dimms not on the > same system. Is there a way to do the BIOS call method in Linux? If it's a sort-of standard way to access SPD info, would it be the one used by CPU-Z to read the SPD info on Windows? (which does work on this HW) > First thing to check is if the SMBus on your system is properly found > and supported: > > # modprobe i2c-dev > # i2cdetect -l > > On an Intel system you should see an entry like: > > i2c-8 smbus SMBus I801 adapter at 0400 SMBus adapter Nope. On 'buntu 10.10, I only got 5 entries (didn't write them down), none of which said smbus. On 11.10, I get: # i2cdetect -l i2c-0 i2c i915 gmbus disabled I2C adapter i2c-1 i2c i915 gmbus ssc I2C adapter i2c-2 i2c i915 GPIOB I2C adapter i2c-3 i2c i915 gmbus vga I2C adapter i2c-4 i2c i915 GPIOA I2C adapter i2c-5 i2c i915 gmbus panel I2C adapter i2c-6 i2c i915 GPIOC I2C adapter i2c-7 i2c i915 gmbus dpc I2C adapter i2c-8 i2c i915 GPIOD I2C adapter i2c-9 i2c i915 gmbus dpb I2C adapter i2c-10 i2c i915 GPIOE I2C adapter i2c-11 i2c i915 gmbus reserved I2C adapter i2c-12 i2c i915 gmbus dpd I2C adapter i2c-13 i2c i915 GPIOF I2C adapter i2c-14 i2c SDVO DDC proxy I2C adapter And BTW, this is the same list I get on my "server/router/AP" (Intel D945GSEJT nettop board running 'buntu 11.04) which is also in the same situation (can't read SPD info). > Then you can check if devices are seen on the bus: > > # i2cdetect 8 > > If you see anything in address range 0x50 to 0x55, this is likely to be > SPD EEPROMs. Then you have to make sure that the eeprom module is > loaded: From the above list, buses 3-6 have a value 0x50 at 0x50 like so: # i2cdetect -y 5 0 1 2 3 4 5 6 7 8 9 a b c d e f 50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Though that's probably irrelevant, as it's not the SMBus, if I understand correctly. -- Using Opera's revolutionary email client: http://www.opera.com/mail/