Hi Mark, On Thu, 7 Apr 2011 07:31:24 +0900, Mark Brown wrote: > On Wed, Apr 06, 2011 at 10:49:17AM -0400, Alan Stern wrote: > > > Neither is the case. For these subsystems, the PM dependencies _are_ > > known. > > ... > > > Now, I have no idea what the situation is with regard to I2C... > > You definitely don't know *anything* about the relationships for I2C, > especially in embedded systems. Can you please elaborate? The i2c subsystem uses a standard parent-children relationship. It seems fairly similar to USB for example. The only special case I can think of is with bus multiplexing, but it would be easy enough to switch off async suspend/resume in this case. Sonny, I would expect you to obtain the time saving by only switching the i2c client device to async suspend/resume. wasn't it the case? i2c bus device suspend/resume shouldn't matter, as the operation should be handled by the hardware (e.g. PCI) layer. Rafael, what happens if a parent is set to async suspend/resume but its children aren't? Does it disable async altogether for the whole branch, or does it mean that the branch is processed asynchronously as a whole but its internal processing is serialized? Or something else? -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
