On Wed, 19 Jan 2011 12:12:49 -0500, Jarod Wilson wrote: > On Jan 19, 2011, at 8:50 AM, Jean Delvare wrote: > > > Hi Andy, > > > > On Wed, 19 Jan 2011 08:38:02 -0500, Andy Walls wrote: > >> As I understand it, the rules/guidelines for I2C probing are now > >> something like this: > >> > >> 1. I2C device driver modules (ir-kbd-i2c, lirc_zilog, etc.) should not > >> do hardware probes at all. They are to assume the bridge or platform > >> drivers verified the I2C slave hardware's existence somehow. > >> > >> 2. Bridge drivers (pvrusb, hdpvr, cx18, ivtv, etc.) should not ask the > >> I2C subsystem to probe hardware that it knows for sure exists, or knows > >> for sure does not exist. Just add the I2C device or not. > >> > >> 3. Bridge drivers should generally ask the I2C subsystem to probe for > >> hardware that _may_ exist. > >> > >> 4. If the default I2C subsystem hardware probe method doesn't work on a > >> particular hardware unit, the bridge driver may perform its own hardware > >> probe or provide a custom hardware probe method to the I2C subsystem. > >> hdpvr and pvrusb2 currently do the former. > > > > Yes, that's exactly how things are supposed to work now. And hopefully > > it makes sense and helps you all write cleaner code (that was the > > intent at least.) > > One more i2c question... > > Am I correct in assuming that since the zilog is a single device, which > can be accessed via two different addresses (0x70 for tx, 0x71 for rx), > that i2c_new_device() just once with both addresses in i2c_board_info > is correct, vs. calling i2c_new_device() once for each address? Preliminary technical nitpicking: you can't actually pass two addresses in i2c_board_info, so the second address has to be passed as platform data. I am sorry if you expected an authoritative answer, but... both options are actually possible. If you use a single call to i2c_new_device(), you'll have a single i2c_client to start with, and you'll have to instantiate the second one in the probe function using i2c_new_dummy(). If you instead decide to call i2c_new_device() twice, there will be two calls to the probe function (which can be the same one in a single driver, or two different ones in separate drivers, at your option.) If any synchronization is needed between the two i2c_clients, you have to use the bridge driver as a relay, as Andy proposed doing already. Really, both are possible, and the two options aren't that different in the end. I can't think of anything that can be done with one that couldn't be achieved with the other. > At least, I'm reasonably sure that was the key to making the hdpvr IR > behave with lirc_zilog, and after lunch, I should know if that's also > the case for pvrusb2 devices w/a zilog IR chip. -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
