Thanks Jean, In fact I'm using the i2c-ocore (opencore) controller, and the «SMBusQuick Command» block the bus with the Linux standard driver(drivers/i2c/busses/i2c-ocores.c):http://www.opencores.org/forums.cgi/cores/2008/10/003391 Then to solve this problem I'm re-writing the driver to support eachSMBus commands separately, following the linux documentation.If writing '1' on quick command block the bus, I will skip this test. FabM On Fri, Jan 9, 2009 at 3:27 PM, Jean Delvare <khali@xxxxxxxxxxxx> wrote:> Salut Fabien,>> On Thu, 8 Jan 2009 10:01:01 +0100, Fabien Marteau wrote:>> I'm writing a driver for i2c controller. To do it, I'm following the>> SMBus protocol description in linux/Documentation/i2c/SMBus->> protocol. This documentation say that we can write a single bit with>> «SMBus Quick Command». This command is used in i2cdetect program to>> find slave on the bus.>>>> I used this command to write bit 0 and that work whell with my slaves,>> but if I try to write bit 1 the slaves addressed are blocking the bus>> (maintain SDA to 0). I tried it with two slaves components :>> LIS3LV02DL (accelerometer) and DS28CZ04 (EEPROM).>>>> Is it a known problem ?>> The SMBus specification describes a number of standardized> transactions. Each chip on the bus can support each given transaction> type or not. In practice, each slave chip only supports a subset of the> SMBus specification. I can't remember working on a chip saying it was> supporting the SMBus quick command. The Linux i2c subsystem abuses this> transaction type for device detection purposes, because it is known to> give good results in practice, but ideally it shouldn't do that.>> There have been some devices known to lock up the SMBus on Quick> command with data bit = 1 (as you are experiencing.) In most cases> these were write-only devices, which didn't expect a transaction> starting like a read (the SMBus specification says that a Quick command> with data bit = 1 is writing 1 bit to the slave, but the I2C> specification says this is a _read_ transaction of length 0.)>> This SMBus Quick command thing keeps causing trouble and confusing> people. Not much we can do though. If your slaves don't like the quick> command, just don't send that command to them.>>> [Erreur de décodage BASE64]>> Gni?>> --> Jean Delvare>��.n��������+%������w��{.n�����{��-��)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
