On 3/5/23 03:26, Geert Uytterhoeven wrote: > Hi Frank, > > On Sun, Mar 5, 2023 at 4:33 AM Frank Rowand <frowand.list@xxxxxxxxx> wrote: >> On 3/2/23 13:47, Geert Uytterhoeven wrote: >>> On Thu, Mar 2, 2023 at 8:28 PM Stephen Boyd <sboyd@xxxxxxxxxx> wrote: >>>> Quoting Rob Herring (2023-03-02 09:32:09) >>>>> On Thu, Mar 2, 2023 at 2:14 AM David Gow <davidgow@xxxxxxxxxx> wrote: >>>>>> On Thu, 2 Mar 2023 at 09:38, Stephen Boyd <sboyd@xxxxxxxxxx> wrote: >>>>>>> This patch series adds unit tests for the clk fixed rate basic type and >>>>>>> the clk registration functions that use struct clk_parent_data. To get >>>>>>> there, we add support for loading a DTB into the UML kernel that's >>>>>>> running the unit tests along with probing platform drivers to bind to >>>>>>> device nodes specified in DT. >>>>>>> >>>>>>> With this series, we're able to exercise some of the code in the common >>>>>>> clk framework that uses devicetree lookups to find parents and the fixed >>>>>>> rate clk code that scans devicetree directly and creates clks. Please >>>>>>> review. >>>>>>> >>>>>> >>>>>> Thanks Stephen -- this is really neat! >>>>>> >>>>>> This works well here, and I love all of the tests for the >>>>>> KUnit/device-tree integration as well. >>>>>> >>>>>> I'm still looking through the details of it (alas, I've mostly lived >>>>>> in x86-land, so my device-tree knowledge is, uh, spotty to say the >>>>>> least), but apart from possibly renaming some things or similarly >>>>>> minor tweaks, I've not got any real suggestions thus far. >>>>>> >>>>>> I do wonder whether we'll want, on the KUnit side, to have some way of >>>>>> supporting KUnit device trees on non-UML architecctures (e.g., if we >>>>>> need to test something architecture-specific, or on a big-endian >>>>>> platform, etc), but I think that's a question for the future, rather >>>>>> than something that affects this series. >>>>> >>>>> I'll say that's a requirement. We should be able to structure the >>>>> tests to not interfere with the running system's DT. The DT unittest >>>>> does that. >>>> >>>> That could be another choice in the unit test choice menu. >>>> CONFIG_OF_KUNIT_NOT_UML that injects some built-in DTB overlay on an >>>> architecture that wants to run tests. >>> >>> As long as you use compatible values that don't exist elsewhere, >>> and don't overwrite anything, you can load your kunit test overlays >>> on any running system that has DT support. >>> >>>>> As a side topic, Is anyone looking at getting UML to work on arm64? >>>>> It's surprising how much x86 stuff there is which is I guess one >>>>> reason it hasn't happened. >>>> >>>> I've no idea but it would be nice indeed. >>> >>> I believe that's non-trivial. At least for arm32 (I didn't have any arm64 >>> systems last time I asked the experts). >>> >>>>>> Similarly, I wonder if there's something we could do with device tree >>>>>> overlays, in order to make it possible for tests to swap nodes in and >>>>>> out for testing. >>>>> >>>>> Yes, that's how the DT unittest works. But it is pretty much one big >>>>> overlay (ignoring the overlay tests). It could probably be more >>>>> modular where it is apply overlay, test, remove overlay, repeat. >>>> >>>> I didn't want to rely on the overlay code to inject DT nodes. Having >>>> tests written for the fake KUnit machine is simple. It closely matches >>>> how clk code probes the DTB and how nodes are created and populated on >>>> the platform bus as devices. CLK_OF_DECLARE() would need the overlay to >>>> be applied early too, which doesn't happen otherwise as far as I know. >>> >>> Don't all generic clock drivers also create a platform driver? >>> At least drivers/clk/clk-fixed-factor.c does. >>> >>>> But perhaps this design is too much of an end-to-end test and not a unit >>>> test? In the spirit of unit testing we shouldn't care about how the node >>>> is added to the live devicetree, just that there is a devicetree at all. >>>> >>>> Supporting overlays to more easily test combinations sounds like a good >>>> idea. Probably some kunit_*() prefixed functions could be used to >>>> apply a test managed overlay and automatically remove it when the test >>>> is over would work. The clk registration tests could use this API to >>>> inject an overlay and then manually call the of_platform_populate() >>>> function to create the platform device(s). The overlay could be built in >>>> drivers/clk/ too and then probably some macroish function can find the >>>> blob and apply it. >>> >>> No need to manually call of_platform_populate() to create the >>> platform devices. That is taken care of automatically when applying >>> an overlay. >>> >>>> Is there some way to delete the platform devices that we populate from >>>> the overlay? I'd like the tests to be hermetic. >> >>> Removing the overlay will delete the platform devices. >> >> I _think_ that is incorrect. Do you have a pointer to the overlay code that >> deletes the device? (If I remember correctly, the overlay remove code does not >> even check whether the device exists and whether a driver is bound to it -- but >> this is on my todo list to look into.) > > https://elixir.bootlin.com/linux/latest/source/drivers/of/platform.c#L769 Thanks! That is precisely what I failed to remember. -Frank > >>> All of that works if you have your own code to apply a DT overlay. >>> The recent fw_devlinks patches did cause some regressions, cfr. >>> https://lore.kernel.org/all/CAMuHMdXEnSD4rRJ-o90x4OprUacN_rJgyo8x6=9F9rZ+-KzjOg@xxxxxxxxxxxxxx > > Gr{oetje,eeting}s, > > Geert >
