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Clark" , "Prasanth Ksr" , "Jorge Lopez" , , "LKML" , Subject: Re: [PATCH v2 0/5] platform/x86: firmware_attributes_class: Add a high level API X-Mailer: aerc 0.20.1-0-g2ecb8770224a References: <20250517-fw-attrs-api-v2-0-fa1ab045a01c@gmail.com> In-Reply-To: --2c76a06105d6073a070457e1f80320a24b936a710f6eb0a98c34f201ae06 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 On Mon Jun 9, 2025 at 6:29 AM -03, Ilpo J=C3=A4rvinen wrote: > On Sun, 8 Jun 2025, Kurt Borja wrote: >> On Sat Jun 7, 2025 at 1:38 PM -03, Joshua Grisham wrote: >> > Den l=C3=B6r 17 maj 2025 kl 10:52 skrev Kurt Borja : >> >> >> >> These series adds the _long awaited_ API for the Firmware Attributes >> >> class. >> >> >> >> You'll find all the details in the commit messages and kernel-doc. >> >> >> >> I think it's easier to understand by example, so I used the >> >> samsung-galaxybook driver for this purpose (last patch). IMO code >> >> readibility, simplicity, maintainability, etc. is greatly improved, b= ut >> >> there is still room for improvement of the API itself. For this reaso= n I >> >> submitted this as an RFC. >> >> >> >> As always, your feedback is very appreciated :) >> >> >> >> Overview >> >> =3D=3D=3D=3D=3D=3D=3D=3D >> >> >> >> Patch 1-2: New API with docs included. >> >> Patch 3: New firwmare attributes type >> >> Patch 4: Misc Maintainers patch >> >> Patch 5: samsung-galaxybook example >> >> >> >> Signed-off-by: Kurt Borja >> >> --- >> >> Changes in v2: >> >> >> >> [Patch 1] >> >> - Include kdev_t.h header >> >> >> >> [Patch 2] >> >> - Use one line comments in fwat_create_attrs() >> >> - Check propagate errors in fwat_create_attrs() >> >> - Add `mode` to fwat_attr_config and related macros to let users >> >> configure the `current_value` attribute mode >> >> - Use defined structs in fwat_attr_ops instead of anonymous ones >> >> - Move fwat_attr_type from config to ops >> >> >> >> [Patch 5] >> >> - Just transition to new API without chaing ABI >> >> >> >> - Link to v1: https://lore.kernel.org/r/20250509-fw-attrs-api-v1-0-25= 8afed65bfa@gmail.com >> >> >> >> --- >> >> Kurt Borja (4): >> >> platform/x86: firmware_attributes_class: Add a high level API >> >> platform/x86: firmware_attributes_class: Add a boolean type >> >> MAINTAINERS: Add FIRMWARE ATTRIBUTES CLASS entry >> >> platform/x86: samsung-galaxybook: Transition to new firmware_at= tributes API >> >> >> >> Thomas Wei=C3=9Fschuh (1): >> >> platform/x86: firmware_attributes_class: Add device initializat= ion methods >> >> >> >> .../ABI/testing/sysfs-class-firmware-attributes | 1 + >> >> MAINTAINERS | 7 + >> >> drivers/platform/x86/firmware_attributes_class.c | 454 +++++++++++= ++++++++++ >> >> drivers/platform/x86/firmware_attributes_class.h | 276 +++++++++++= ++ >> >> drivers/platform/x86/samsung-galaxybook.c | 308 ++++++-----= --- >> >> 5 files changed, 861 insertions(+), 185 deletions(-) >> >> --- >> >> base-commit: 9f080c9f2099b5a81c85b3b7f95fd11fad428cc8 >> >> change-id: 20250326-fw-attrs-api-0eea7c0225b6 >> >> -- >> >> ~ Kurt >> >> >> > >> > Hi Kurt! First let me begin by saying GREAT job in picking this up, >> > carrying on the work from Thomas, and really trying to glue all of the >> > various pieces together into a packaged solution that can finally see >> > the light of day :) >> > >> > Sorry it has taken some time for me to get back to you--work and other >> > life stuff seemed to always get in the way and I wanted to make sure I >> > took enough time to really think about this before I were to give any >> > feedback myself. >> > >> > First off, the quick and easy one: I applied all of your patches (on >> > top of 6.15.1), tested everything with samsung-galaxybook from my >> > device, and everything is still working without any failures and all >> > features work as I expect them to. I diffed everything under >> > /sys/class/firmware-attributes before vs after and everything is >> > exactly the same EXCEPT it looks like what is currently >> > "default_value" will now be called "default" with your patch. I assume >> > if the intention is to keep the ABI same as before then you would >> > probably want to change this? Specifically here: >> > >> >> +static const char * const fwat_prop_labels[] =3D { >> >> + [FWAT_PROP_DISPLAY_NAME] =3D "display_name", >> >> + [FWAT_PROP_LANGUAGE_CODE] =3D "display_name_language_code", >> >> + [FWAT_PROP_DEFAULT] =3D "default", >> > >> > Assume the last line should instead be >> > >> > [FWAT_PROP_DEFAULT] =3D "default_value", >> > >> > or maybe even for consistency to rename the fwat_property to also >> > match and then it could be like this? >> > >> > [FWAT_PROP_DEFAULT_VALUE] =3D "default_value", >>=20 >> Yes! You are correct. I completely missed this. >>=20 >> > >> > FWIW I don't personally mind changing the ABI for samsung-galaxybook; >> > as you mentioned it is basically a brand new driver and the solutions >> > which exist "in the wild" for it are quite limited so better maybe >> > that it looks "right" going forward instead of carrying any >> > unnecessary baggage, but I can understand that this may not be the >> > case for all of the other drivers which have been using these >> > facilities for a longer time period. >>=20 >> This was my first thought but I found out fwupd uses this interface. >> I'll leave the ABI as is to not incur in regressions. >>=20 >> > >> > Past that, I certainly think this is a big step forward as compared to >> > messing around with the lower level kset / kobj_attribute etc >> > facilities and trying to set everything up from scratch without so >> > many helper utilities. As you may have noticed, what I ended up doing >> > in samsung-galaxybook was essentially to create my own local >> > implementation of some kind of "standard" fw attributes (but only for >> > booleans), but it would be even better if this were standardized >> > across all drivers! There are a few things left over in >> > samsung-galaxybook that still need to be cleaned up from your >> > suggested change (e.g. the struct galaxybook_fw_attr can now be >> > totally removed, etc) which we can also address at some point, of >> > course! >>=20 >> Thanks! I'll clean them in the next revision. >>=20 >> > >> > But just to take a step back for a moment, and what I have been really >> > trying to think through and reflect on myself for a few hours with >> > this change... >> > >> > (Please feel free to completely disregard the below if this has >> > already been brought up and ruled out, or anyone else has any opinions >> > against this; all of that feedback is welcome and most definitely >> > trumps my own meager opinions! ;) Also please remember that it is not >> > my intention at all to detract from any of the great work that has >> > already been done here -- just the stuff that my brain kind of gets >> > "stuck" on as I try to think through the bigger picture with this! ) >>=20 >> Don't worry, feedback is always appreciated :) >>=20 >> > >> > If I think in terms of anyone who wants to come in and work on device >> > drivers in the kernel, then they will potentially need to learn >> > facilities for multiple different kind of "attributes" depending on >> > their use case: device attributes, driver attributes, hwmon's >> > sensor-related attributes, bus attributes, etc etc, and for the most >> > part, I think they ALL have basically the same kind of interface and >> > facilities. It feels very unified and relatively easy to work with all >> > of them once you have basically figured out the scheme and conventions >> > that have been implemented. >> > >> > Now, when I look at the proposal from these patches, these "Firmware >> > Attributes" do not seem to have the same kind of "look, feel, and >> > smell" as the other type of attributes I just mentioned, but instead >> > feels like a totally new animal that must be learned separately. My >> > take on it would be that a desired/"dream" scenario for a device >> > driver developer is that all of these interfaces sort of look and >> > "smell" the same, it is just a matter of the name of the macro you >> > use, which device you attach the attributes to (which registration >> > function you need to execute??), and maybe some small subtle >> > differences in the facilities as appropriate to their context. >> > >> > Specifically with firmware attributes vs the other kinds, I guess the >> > biggest differences are that: >> > 1) There is a display_name with a language code >> > 2) There are built-in restrictions on the input values depending on a >> > "type" (e.g. "enumeration" type has a predetermined list of values, >> > min/max values or str lengths for numeric or string values, etc) >> > 3) There is a default_value >> > 4) *Maybe* there should be some kind of inheritance and/or sub-groups >> > (e.g. the "authentication" and similar extensions that create a group >> > under the parent group...) >>=20 >> I'm not sure what you mean by this. If you mean this API should also >> offer a way to create the Authentication group, I agree! >>=20 >> I was just hoping to get feedback from other maintainers before doing >> that. I want to know if this approach passes the "smell" test for >> everyone. >>=20 >> > >> > But at the end of the day, my hope as a developer would be to be able >> > to create these firmware attributes in much the same way as the other >> > types. E.g. maybe something like this quick and dirty pseudo example: >> > >> > >> > static ssize_t power_on_lid_open_show(struct device *dev, >> > struct device_attribute *attr, >> > char *buf) >> > { >> > // ... >> > } >> > >> > static ssize_t power_on_lid_open_store(struct device *dev, >> > struct device_attribute *attr, >> > const char *buf, size_t count) >> > { >> > // ... >> > } >> > >> > static FW_BOOL_ATTR_RW(power_on_lid_open, "Power On Lid Open"); >> > >> > static struct attribute *galaxybook_fw_attrs[] =3D { >> > // ... other fw attrs not shown above ... >> > &fw_attr_power_on_lid_open.attr, >> > NULL >> > }; >> > >> > static const struct attribute_group galaxybook_fw_attrs_group =3D { >> > .attrs =3D galaxybook_fw_attrs, >> > .is_visible =3D galaxybook_fw_attr_visible, >> > }; >> > >> > static int galaxybook_fw_attrs_init(struct samsung_galaxybook *galaxyb= ook) >> > { >> > // ... >> > >> > /* something like "devm_fw_attr_device_register" could be sort >> > of similar to >> > how devm_hwmon_device_register_with_groups works ? */ >> > >> > ret =3D devm_fw_attr_device_register(&galaxybook->platform->de= v, >> > DRIVER_NAME, galaxybook, >> > &galaxybook_fw_attrs_group); >> > return PTR_ERR_OR_ZERO(ret); >> > } >> > >> > >> > Or in other words: >> > - I create my callback functions for "show" and "store" with a certain >> > named prefix and then use a macro to create the struct for this fw >> > attr that relies on that these functions exist (e.g. in the above >> > example the macro would create this "fw_attr_power_on_lid_open" fw >> > attr structure instance) -- note here it might need to be a macro per >> > type and/or to include the type-related stuff (including value >> > constraints/enumeration arrays/default values/etc) as parameters to >> > the macro, plus maybe I would want to provide some kind of context >> > parameter e.g. I would maybe want a pointer to my samsung_galaxybook >> > ideally somehow to get to come along?? (that might affect the >> > signature of my above examples of course! they were just a >> > quick-and-dirty example...), >>=20 >> I agree and I believe this API has this capability. You can do this: >>=20 >> static int power_on_lid_open_read(struct device *dev, long aux, const ch= ar **str) >> { >> ... >> } >>=20 >> static int power_on_lid_open_write(struct device *dev, long aux, const c= har *str, size_t count) >> { >> ... >> } >>=20 >> static ssize_t power_on_lid_open_prop_read(struct device *dev, long aux,= enum fwat_property prop, >> char *buf) >> { >> ... >> } >>=20 >> DEFINE_FWAT_OPS(power_on_lid_open, enumeration); >>=20 >> ... >>=20 >> static const struct fwat_attr_config * const galaxybook_fwat_config[] = =3D { >> FWAT_CONFIG_AUX("power_on_lid_open", 0644, >> GB_ATTR_POWER_ON_LID_OPEN, >> &power_on_lid_open_ops, >> galaxybook_fwat_props, >> ARRAY_SIZE(galaxybook_fwat_props)), >> ... >> NULL >> } >>=20 >> I.e, you can define ops for each "firmware attribute" (aka >> attribute_group). >>=20 >> I feel the _props approach is currently a bit ugly though, and there is >> room for improvement in the boilerplate department. >>=20 >> In the samsung-galaxybook case I decided to define a single struct >> fwat_attr_ops because I didn't want to make the diff too ugly. The >> *_acpi_{get,set}() functions that already exist are used in other parts >> of the driver, and I would have to change a few lines to make it work. >>=20 >> BTW, you can pass a drvdata pointer to devm_fwat_device_register(). >>=20 >> > - put all of my desired attrs together in a group where I can specify >> > their is_visible callback (just like you do with DEVICE_ATTRs), >>=20 >> I decided to make this a single callback defined in struct >> fwat_dev_config. I went for this because I didn't like the idea of a >> different function for each attribute_group because it would just be a >> bunch of functions. >>=20 >> > - and then register my fw attr device with my attribute_group (the >> > register function would take care of all the rest..) >>=20 >> Do you think the struct fwat_attr_config * list achieves this? Could it >> be improved in some way? >>=20 >> > >> > And as sort of shown in the above example I certainly think it would >> > be nice if the naming convention lined up nicely with how the naming >> > convention works for the existing attribute stuff (e.g. DEVICE_ATTR_RW >> > vs DRIVER_ATTR_RW vs something like "FW_ATTR_RW" or "FIRMWARE_ATTR_RW" >> > seems like it falls into the same convention??) >>=20 >> I can certainly add these macros, but they would be for "firmware >> attributes" defined entirely manually, using struct fwat_attribute. >> Actually I thought of adding these, but I didn't do it because I wanted >> to get something working at first and then add some of these extra >> helpers. >>=20 >> > >> > Again I am not trying to "rock the boat" here, and I have not >> > necessarily *really* thought through all of the implications to the >> > existing fw attrs extensions and how they might be able to be >> > implemented with the above kind of example, ... I'm just taking a step >> > back and sharing my observations of the patch compared to how it >> > actually looks in the driver with the example vs how most of the other >> > existing attribute facilities have been designed. >>=20 >> Thank you! As I said before, feedback is always welcome. >>=20 >> I feel this API already accomplishes the requirements (which I agree >> with) you listed, albeit with some (maybe a bit too much) boilerplate. >> However your questions make me realise documentation is still lacking, I >> will make it better for the next revision. >>=20 >> If you have more concrete areas of improvement, please let me know! I >> know there is room for improvement. Especially with naming. >>=20 >> > >> > One more final thing which I always felt a little "off" about -- is it >> > not the case that other type of platforms might could use firmware >> > attributes as well? Or is this considered ONLY an x86 thing (e.g. that >> > "firmware" relates to "BIOS" or something) ? Because I always thought >> > it a bit strange that the header file was only local to >> > ./drivers/platform/x86/ instead of being part of the Linux headers >> > under ./include .. >>=20 >> I agree! I'd like to know maintainers opinion on this. > > We do move code and headers around whenever we find out the initial=20 > placement isn't good any more, it's business as usual. > > Usually when something feels off to you, it is off. But I understand=20 > in these situations there's often the nagging voice telling inside one's= =20 > head 'Am I missing something obvious here?'; which rarely is the case ;-)= .=20 > There's no need to assume the existing code is 'perfect' (including its= =20 > placement). :-) Then I'll move it to ./include/. Thanks Ilpo :) --=20 ~ Kurt --2c76a06105d6073a070457e1f80320a24b936a710f6eb0a98c34f201ae06 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQSHYKL24lpu7U7AVd8WYEM49J/UZgUCaEcwHwAKCRAWYEM49J/U Zq8CAQDIsKHYZjse6NzLBdK0yRKW+hzRVSj7lwyRpJLuEZJbpQD/e9Tq/ZYRH0iz DJ44hTQAM7JYu+/e3+OAR8MD4Ld6Kwo= =BxjD -----END PGP SIGNATURE----- --2c76a06105d6073a070457e1f80320a24b936a710f6eb0a98c34f201ae06--