Thanks for your guys' brainstorm. I will take all the thoughts into account while implementing this.
On Wed, Oct 13, 2010 at 2:49 PM, Amit Kucheria <amit.kuche...@linaro.org>wrote: > 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 >
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