> > Ok. So I may have misunderstood what names were for. In my mind, those > > were the name of the clock input on the HW device :-) > > Oh, I do hope I didn't say that was wrong, because that is quite > correct. What the idea with passing a NULL 'name' with drivers > which only had one input was to force people to avoid using 'name' > as the sole way to match.
I see. So basically, they are meant to be the input names, but have been abused by people to be "global scope" clock names and hence mess happened. > When I originally wrote the AMBA primecell drivers, I did use things > like 'UARTCLK' and 'AACICLK' for the clk_get() name - since these > were the name on the device, and that really only provided people > with a bad example to follow. Especially if you consider that the > hardware I had was FPGA based development boards where the clocking > layout lent itself well to ignoring the 'dev' argument. Right. > > Right. I didn't intend to name the clock sources. I intended to name the > > clock -inputs- of a given device. IE. clk_get(dev, name) in my mind > > meant "give me the clock provider that feeds my "name" input). > > That's absolutely the right way to look at it! Cool :-) It did feel right indeed. > > Allright but passing a NULL doesn't help for drivers with multiple clock > > inputs. IE. How do you want to deal with that ? Do you want to deprecate > > the named API and instead provide a new clk_get_for_input(dev, > > clk_input) (clk_input could be name or numerical ... tbd) ? > > NULL certainly doesn't help for drivers with multiple clock inputs. > For those, you have to explicitly name the input. To take the > example commits I pointed at (the OMAP watchdog driver) OMAP blocks > generally have two clock inputs - a functional clock and an > interface clock. Right, that's a common setup. > Originally, the driver was effectively setup to match by clock source > name (wdt2_fck, wdt2_ick) which was SoC specific. What the commits > did was convert things to looking using the names of the inputs > (aka consumer name) - so dev + "fck" and dev + "ick". Ok, cool, so we are on the same page. > That results in clkdev looking up the clocks for device "omap_wdt" > for inputs "fck" and "ick" respectively. On OMAP1 platforms, there > isn't an "ick" as such, so there's a match-any-device dummy "ick" > entry. On OMAP2 and OMAP3 (the later revs) there are specific > clocks for these, and so the dummy entry is missing. > > So, the approach I took was: where it is well defined that a device > has only one clock input, we pass a NULL name. If it has more than > one clock input, we pass the specific consumer name required. Makes sense. I think this will work beautifully with the device-tree too with the idea of having properties that then provide the binding for a given clock input to the clock provider and the clock ID on that provider (my proposal makes the later a number because doing strings can be awkward in OF land in such mapping tables but I might go back to strings, we'll see). > > Or am I missing a piece of the puzzle ? > > Maybe - and since you're just starting to look at clkdev, I'll point > out that it's actually not intuitive which way around the "wildcard" > matching works in clkdev. The clk_get() arguments aren't the > wildcards, they're in the clk_lookup structure. Yes, it seems odd, > but if you consider it from the point of view of the platform code > wanting to match clocks to a specific set of devices and clock inputs, > it's actually the way around that you want. Ok. I'll read up a bit and see if I can get my head around it. Thanks ! Cheers, Ben. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
