Hi Manu: * Manu Abraham <abraham.manu at gmail.com> [2006-06-02 15:38:01 +0400]: > DVB doesn't probe for i2c devices. The DVB adapter, ie the card knows > what devices that are present and works under that assumption. > > Earlier DVB had the problem with probing. ie a different device is found > at the expected location of another device(In the case of probing) and > this device doesn't like to be fiddled around with. And "lo" we have a > perfect freeze. > > After many such cases, DVB no longer probes for i2c devices (we now > longer have anymore i2c issues) > V4L on the other hand probes for all devices. This is IMHO wrong, due to > > (1) When the probe list grows long, it takes longer time for the probe > to succeed (V4L guys themselves would agree to the fact that they have > seen probes in the order of ~30 minutes ! Yuck) > > (2) Probing wrong devices > > So in any case probing can never be right, unless the card information > is passed to the i2c core. But in that sense it is no longer a probe. It > is indeed just an attach method. In that case, it makes no sense to make > i2c core go around in circles. The driver model code itself has a lot of back-and-forth delegation, i.e. 'around in circles'. If the i2c core can be made flexible enough to address all the requirements, why wouldn't that be the best place for it? > The proper way to handle this, is that only the right device is > attached. Rather than making i2c to do this, subsystems should be > handling this. Are you saying that the probing which is absolutely necessary for hwmon should be moved out of i2c-core and into a separate hwmon subsystem? If so, that's interesting, I guess... do you then disagree with the *premise* of Nathan's patches? I mean, "DVB which no longer probes" is one of its goals after all. Actually, Manu: may I ask a favor? Could you please point out what are some of the most difficult and/or sticky "problem drivers" regarding DVB vs. I2C, and perhaps even describe what makes each particular instance such a pain for you? I would appreciate it. Regards, -- Mark M. Hoffman mhoffman at lightlink.com
