> If this limitations exists >they are not introduced by this patch. This patch just exposes the >frequency so that it can be read or changed in userspace. Ah, well right now you can have an i2c bus with driver 1 and 2. Say the i2c bus is configured for 60khz in kernel space which normally can't be changed. Driver 1 talks to a slave that cannot go above 100khz. Now the userspace interface is added to the i2c bus. Some userspace application decides to reconfigure the bus for 400khz and do its communication to some slave device. Now the kernel tries to do some background talking to the drive 1 slave and suddenly finds it can no longer communicate with it. Right now with the kernel space only configuration, the system is safe from being messed up easily. It's more of a sanity of configuration issue. >On a different not, I have noticed that a fixed set of frequencies >might not be the best API, since multiple drivers rather support a >rather large set of frequencies in a range. A better API might be to >expose a min-max range and let the bus driver adjust the requested >frequency. I will follow up with a second version that does that. I was actually thinking you could eliminate the table of supported frequencies and just have the bus driver handle the set frequency decision itself and just return an error code if it's invalid. There are legitiamate drivers that cannot do more than a list of frequencies already as well. One example is here: http://lxr.free-electrons.com/source/drivers/i2c/busses/i2c-bcm-kona.c#L717 -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
