2013/4/11 Guennadi Liakhovetski <g.liakhovetski@xxxxxx>: > Hi Barry > > On Thu, 11 Apr 2013, Barry Song wrote: > >> Hi Guennadi, >> >> > Typical video devices like camera sensors require an external clock source. >> > Many such devices cannot even access their hardware registers without a >> > running clock. These clock sources should be controlled by their consumers. >> > This should be performed, using the generic clock framework. Unfortunately >> > so far only very few systems have been ported to that framework. This patch >> > adds a set of temporary helpers, mimicking the generic clock API, to V4L2. >> > Platforms, adopting the clock API, should switch to using it. Eventually >> > this temporary API should be removed. >> >> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx> >> > --- >> >> for your patch 1/8 and 3/8, i think it makes a lot of senses to let >> the object manages its own clock by itself. >> is it possible for us to implement v4l2-clk.c directly as an instance >> of standard clk driver for those systems which don't have generic >> clock, and remove the V4L2 clock APIs like v4l2_clk_get, >> v4l2_clk_enable from the first day? i mean v4l2-clk.c becomes a temp >> and fake clock controller driver. finally, after people have >> generically clk, remove it. > > I don't think you can force-enable the CFF on systems, that don't support > it, e.g. PXA. yes. we can. clock is only a framework, has it any limitation to implement a driver instance on any platform? people have tried to move to common clk and generic framework for a long time, now you still try to provide a v4l2 specific clock APIs, it just makes v4l2 unacceptable and much complex. > > Thanks > Guennadi > >> > v8: Updated both (C) dates >> >> > drivers/media/v4l2-core/Makefile | 2 +- >> > drivers/media/v4l2-core/v4l2-clk.c | 177 ++++++++++++++++++++++++++++++++++++ >> > include/media/v4l2-clk.h | 54 +++++++++++ >> > 3 files changed, 232 insertions(+), 1 deletions(-) >> > create mode 100644 drivers/media/v4l2-core/v4l2-clk.c >> > create mode 100644 include/media/v4l2-clk.h >> >> > diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile >> > index aa50c46..628c630 100644 >> > --- a/drivers/media/v4l2-core/Makefile >> > +++ b/drivers/media/v4l2-core/Makefile >> > @@ -5,7 +5,7 @@ >> > tuner-objs := tuner-core.o >> >> > videodev-objs := v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o \ >> > - v4l2-event.o v4l2-ctrls.o v4l2-subdev.o >> > + v4l2-event.o v4l2-ctrls.o v4l2-subdev.o v4l2-clk.o >> > ifeq ($(CONFIG_COMPAT),y) >> > videodev-objs += v4l2-compat-ioctl32.o >> > endif >> > diff --git a/drivers/media/v4l2-core/v4l2-clk.c b/drivers/media/v4l2-core/v4l2-clk.c >> > new file mode 100644 >> > index 0000000..d7cc13e >> > --- /dev/null >> > +++ b/drivers/media/v4l2-core/v4l2-clk.c >> > @@ -0,0 +1,177 @@ >> >> -barry -barry -- 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
