On Wednesday, December 08, 2010 05:12:22 Kim, HeungJun wrote: > Hi Hans and everyone, > > I wonder if the subdev driver need pm features, like a power-off when suspend and power-on when resume. > Commonly, It seems alright that the platform driver using this subdev driver must do such process. > But, thinking deeply, irrelevantly at this dependency of the platform and the subdev, > I think the subdev driver must support pm features. > If the platform driver dosen't support subdev driver's pm, the ISP or camera device controlled with non-pm-support subdev driver, may have a problems when the system is suspended/resumed. > > In the subev driver, using pm or not. which one is right?? Both. It depends on the type of hardware. Most subdevs are i2c drivers. And pm is a standard feature of such drivers. Proper pm is unfortunately rarely implemented in v4l drivers, but there are a few i2c subdev drivers that do it. If a subdev is not part of a i2c/spi bus, then pm is more likely handled by the main v4l driver which will call s_power whenever a subdev needs to power up or down. Regards, Hans -- Hans Verkuil - video4linux developer - sponsored by Cisco -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
