On Fri, 18 May 2007, Johannes Stezenbach wrote: > On Fri, May 18, 2007 at 04:48:13PM +0200, e9hack wrote: > > Johannes Stezenbach wrote: > > > According to linux/Documentation/i2c/i2c-protocol.txt the correct > > > way to get a STOP condition between two I2C messages is send them > > > in seperate I2C transactions. > > > > I don't find this description in i2c-protocol. > > It's not written explicitly, but it says > you need to use a "Simple send transaction" and/or > a "Simple receive transaction" instead of a > "Combined transaction" if you want a STOP bit > in between. That's how i2c-core is designed. > > > IMHO, it isn't possible > > to split a read request into a single write and a single read request > > outside of the core device. The device must be locked during both > > transfers. If the device isn't locked, it is possible that another > > transfer will change the slave offset before the content is read. This > > may occur with the current implementation. > > If locking is necessary the drivers would need to > handle this explicitely (I think it isn't unless ou start > messing mith /dev/i2c concurrently). > > Or you could propose a change to i2c-core to add > a I2C_M_STOP flag (analogous to I2C_M_NOSTART), which > then would have to be implemented by all i2c bus drivers. It seems like this is the only way to send multiple stops in a single atomic transaction. All drivers wouldn't have to implement it, just the ones where someone actually wants this ability. Few drivers actually implement all of the existing i2c features. _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
