On Tue, 22 Mar 2011, Martin, LoicX wrote: > Hi > > I found those drivers: > > drivers/dma/intel_mid_dma.c This driver uses the legacy PM interface, and it appears that the runtime_suspend method was piggybacked on top of that. Consequently it was not done properly. > drivers/i2c/busses/i2c-intel-mid.c This driver simply needs to be changed. You could write to the maintainers of these drivers, informing them of the problem. > drivers/staging/gma500/psb_drv.c > drivers/staging/gma500/psb_powermgmt.c > drivers/staging/intel_sst/intel_sst.c Nobody expects code in drivers/staging to be a paragon of good style. Again, you could write to the maintainers. > We are currently working on this purpose (runtime suspend/resume implementation), and our first understanding was not perfectly clear. > That's why I was asking about the correct implementation of those callback. There are plenty of other examples showing the right way to do it. > Thanks > > I have one more question about this part of the documentation: > >>However, the driver should not call the pm_runtime_allow() helper function unblocking > >>the runtime PM of the device. Instead, it should allow user space or some > >>platform-specific code to do that > > Is there any reason concerning the system stability or something else to do it that way instead of doing it in the driver during the probe ? People have had bad experiences with devices that don't work correctly with runtime-suspend. I don't know how well-behaved most PCI devices are in this regard, but a lot of USB devices fail miserably. Hence the decision to have some subsystems forbid runtime-suspend by default, leaving userspace to decide whether runtime-suspend should be allowed. If you've got a driver for a device that you _know_ will work correctly with runtime-suspend, you can go ahead and call pm_runtime_allow() during probe. Alan Stern _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
