Am 11.06.2015 um 13:24 schrieb Alexander Holler: > Am 11.06.2015 um 12:17 schrieb Alexander Holler: >> Am 11.06.2015 um 10:12 schrieb Linus Walleij: >>> On Wed, Jun 10, 2015 at 10:28 AM, Alexander Holler >>> <holler@xxxxxxxxxxxxx> wrote: >>>> Am 10.06.2015 um 09:30 schrieb Linus Walleij: >>> >>>>> i2c host comes out, probes the regulator driver, regulator driver >>>>> probes and then the regulator_get() call returns. >>>>> >>>>> This requires instrumentation on anything providing a resource >>>>> to another driver like those I mentioned and a lot of overhead >>>>> infrastructure, but I think it's the right approach. However I don't >>>>> know if I would ever be able to pull that off myself, I know talk >>>>> is cheap and I should show the code instead. >>>> >>>> You would end up with the same problem of deadlocks as currently, and >>>> you >>>> would still need something ugly like the defered probe brutforce to >>>> avoid >>>> them. >>> >>> Sorry I don't get that. Care to elaborate on why? >> >> Because loading/initializing on demand doesn't give you any solved order >> of drivers to initialize. And it can't because it has no idea about the >> requirements of other drivers. The reason why it might work better in >> the case of the tegra is that it might give you another initialization >> order than the one which is currently choosen, which, by luck, might be >> a better one. >> >> But maybe I missed something, I haven't looked at the patches at all. >> But just loading on demand, can't magically give you a working order of >> drivers to initialize. E.g. how do you choose the first driver to >> initialize? > > Other problems you will run into are time constraints and multithreaded > drivers. > > E.g. we all should know how tricky it sometimes is to avoid deadlocks. > And with loading on demand, you are extending this problem over the > initialization of maybe a whole bunch of other drivers which might be > started by calling one function of another driver. And a function call > might need a very long time to finish during which an unpredictable > amount of things may happen. > > It would make me wonder if that will end up with a good, usable and as > simple as possible solution. Besides that instrumenting every call to another driver in order to fix a onetime operation (the initialization) sounds like an enormous overhead. Initialization is done pnly once, regardless how long a system runs, but the instrumentation to fix this onetime operation would slow down the operation during the whole runtime of a system. I don't think this is what should be done. > > Regards, > > Alexander Holler -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
