On 10 Oct 12, Arnd Bergmann wrote: > On Tuesday 12 October 2010, Amit Kucheria wrote: > > Adding linaro-dev to cc. Kernel consolidation WG might have comments. > > > > On Tue, Oct 12, 2010 at 9:04 AM, Yong Shen <yong.s...@linaro.org> wrote: > > > Hi Amit and Jeremy, > > > > > > This is not a patch review. But patch may better present my idea. > > > Basically, > > > I want to add some code in common clock code to export clock information, > > > so > > > every platform can benefit. This information is present in a tree-like > > > pattern. > > > Currently, each platform uses their own way to show clock info, which is > > > hard to use a common user space tool to collect information. > > > For this purpose, I need do the rest: > > > 1. Add a clock name check in the clkdev_add. We don't accept two clocks > > > with > > > the same name to clkdev_add, do we? otherwise, it is impossible to create > > > a > > > tree-like structure under file system, cause no same names under a > > > directory. > > > 2. Recursive function creates the clock tree in debugfs, which referred > > > omap's clock implementation. > > > 3. Add interface needed to let mach related drivers to report their > > > information. clk_get_rate is already there. Maybe we need clk_get_flags() > > > and clk_get_usecount() and more. > > > > Agreed, this functionality is necessary for common clk infrastructure > > to be useful. > > I like the idea, too. > > One question I immediately had was whether it should be integrated into > sysfs or remain standalone in debugfs. > > In general, no core functionality should require debugfs, so if we find > it important enough to write user level tools on top of this, it should > probably become a stable interface either in sysfs or its own "clkfs" > file system if necessary.
That is something I've been wondering about too. At the moment, tools like powerdebug have to periodically re-read the entire clock tree to show updates. AFAIK, sysfs and debugfs don't support inotify/poll/select mechanisms to notify changes. It would be nice to have notification, but I don't know how hard that would be for a virtual filesystem. > The main disadvantage of sysfs is probably memory consumption, which will > have to be evaluated carefully: on systems with little RAM but many clocks > this might amount to a few percent of the system memory just to manage > the inodes. > > The main advantage of sysfs is that we can interface it with the device tree, > e.g. have a "clk" symlink in each device pointing to the entry in > the clock tree, and possibly vice versa. Agreed. /Amit _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
