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([2a10:a5c0:800d:dd00:8fdf:935a:2c85:d703]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5452fcf6487sm1893226e87.137.2025.02.20.06.21.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 20 Feb 2025 06:21:40 -0800 (PST) Message-ID: <9018e23c-da28-41b0-b774-1598b946a2a1@gmail.com> Date: Thu, 20 Feb 2025 16:21:37 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/9] iio: adc: add helpers for parsing ADC nodes To: Andy Shevchenko Cc: Matti Vaittinen , Jonathan Cameron , Lars-Peter Clausen , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Lad Prabhakar , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , Hugo Villeneuve , Nuno Sa , David Lechner , Javier Carrasco , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev References: <6c5b678526e227488592d004c315a967b9809701.1739967040.git.mazziesaccount@gmail.com> Content-Language: en-US, en-AU, en-GB, en-BW From: Matti Vaittinen In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250220_062144_476396_EB615197 X-CRM114-Status: GOOD ( 54.26 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 20/02/2025 16:04, Andy Shevchenko wrote: > On Thu, Feb 20, 2025 at 03:40:30PM +0200, Matti Vaittinen wrote: >> On 20/02/2025 14:41, Andy Shevchenko wrote: >>> On Thu, Feb 20, 2025 at 09:13:00AM +0200, Matti Vaittinen wrote: >>>> On 19/02/2025 22:41, Andy Shevchenko wrote: >>>>> On Wed, Feb 19, 2025 at 02:30:27PM +0200, Matti Vaittinen wrote: > > ... > >>>>>> +EXPORT_SYMBOL_GPL(iio_adc_device_num_channels); >>>>> >>>>> No namespace? >>>> >>>> I was considering also this. The IIO core functions don't belong into a >>>> namespace - so I followed the convention to keep these similar to other IIO >>>> core stuff. >>> >>> But it's historically. We have already started using namespaces >>> in the parts of IIO, haven't we? >> >> Yes. But as I wrote, I don't think adding new namespaces for every helper >> file with a function or two exported will scale. We either need something >> common for IIO (or IIO "subsystems" like "adc", "accel", "light", ... ), or >> then we just keep these small helpers same as most of the IIO core. > > It can be still pushed to IIO_CORE namespace. Do you see an issue with that? No. I've missed the fact we have IIO_CORE O_o. Thanks for pointing it out! > Or a new opaque namespace for the mentioned cases, something like IIO_HELPERS. I am unsure if it really benefits to split this out of the IIO_CORE. I've a feeling it falls into the category of making things harder for user with no apparent reason. But yes, the IIO_CORE makes sense. >>>> (Sometimes I have a feeling that the trend today is to try make things >>>> intentionally difficult in the name of the safety. Like, "more difficult I >>>> make this, more experience points I gain in the name of the safety".) >>>> >>>> Well, I suppose I could add a namespace for these functions - if this >>>> approach stays - but I'd really prefer having all IIO core stuff in some >>>> global IIO namespace and not to have dozens of fine-grained namespaces for >>>> an IIO driver to use... > > ... > >>>>>> + if (!allowed_types || allowed_types & (~IIO_ADC_CHAN_PROP_TYPE_ALL)) { >>>>> >>>>> Unneeded parentheses around negated value. >>>>> >>>>>> + if (found_types & (~allowed_types)) { >>>>> >>>>> Ditto. >>>>> >>>>>> + long unknown_types = found_types & (~allowed_types); >>>>> >>>>> Ditto and so on... >>>>> ... >>>> during the moves I lost my printed list of operator precedences which I used >>>> to have on my desk. I've been writing C for 25 years or so, and I still >>>> don't remember the precedence rules for all bitwise operations - and I am >>>> fairly convinced I am not the only one. >>> >>> ~ (a.k.a. negation) is higher priority in bitops and it's idiomatic >>> (at least in LK project). >> >> I know there are well established, accurate rules. Problem is that I never >> remember these without looking. > > There are very obvious cases like below. I think we just disagree on if this is obvious. >>>> What I understood is that I don't really have to have a printed list at >>>> home, or go googling when away from home. I can just make it very, very >>>> obvious :) Helps me a lot. >>> >>> Makes code harder to read, especially in the undoubtful cases like >>> >>> foo &= (~...); >> >> This is not undoubtful case for me :) And believe me, reading and >> deciphering the >> >> foo &= (~bar); >> >> is _much_ faster than seeing: > > Strongly disagree. One need to parse an additional pair of parentheses, > and especially when it's a big statement inside with nested ones along > with understanding what the heck is going on that you need them in the > first place. > > On top of that, we have a common practices in the LK project and > with our history of communication it seems you are trying to do differently > from time to time. Sounds like a rebellion to me :-) I only rebel when I (in my opinion) have a solid reason :) >> foo &= ~bar; >> >> and having to google the priorities. > > Again, this is something a (regular) kernel developer keeps refreshed. > Or even wider, C-language developer. Ha. As I mentioned, I've been writing C on a daily bases for almost 25 years. I wonder if you intent to say I am not a kernel/C-language developer? Bold claim. >>>>>> + int type; >>>>>> + >>>>>> + for_each_set_bit(type, &unknown_types, >>>>>> + IIO_ADC_CHAN_NUM_PROP_TYPES - 1) { >>>>>> + dev_err(dev, "Unsupported channel property %s\n", >>>>>> + iio_adc_type2prop(type)); >>>>>> + } >>>>>> + >>>>>> + return -EINVAL; >>>>>> + } > > ... > >>>>>> + tmp.required &= (~BIT(IIO_ADC_CHAN_PROP_COMMON)); >>>>> >>>>> Redundant outer parentheses. What's the point, please? >>>> >>>> Zero need to think of precedence. >>> >>> Huh? See above. >>> Everything with equal sign is less precedence than normal ops. >> >> Sure. It's obvious if you remember that "Everything with equal sign is less >> precedence than normal ops". But as I said, I truly have hard time >> remembering these rules. When I try "going by memory" I end up having odd >> errors and suggestions to add parenthesis from the compiler... > > The hardest to remember probably the > > foo && bar | baz > > case and alike. These are the only ones that I totally agree on with you. > But negation. > >> By the way, do you know why anyone has bothered to add these >> warnings/suggestions about adding the parenthesis to the compiler? My guess >> is that I am not only one who needs the precedence charts ;) > > Maybe someone programmed too much in LISP?.. (it's a rhetorical one) > > ... > >>>>>> + ret = fwnode_property_read_u32(child, "common-mode-channel", >>>>>> + &common); >>>>> >>>>> I believe this is okay to have on a single line, >>>> >>>> I try to keep things under 80 chars. It really truly helps me as I'd like to >>>> have 3 parallel terminals open when writing code. Furthermore, I hate to >>>> admit it but during the last two years my near vision has deteriorated... :/ >>>> 40 is getting more distant and 50 is approaching ;) >>> >>> It's only 86 altogether with better readability. >>> We are in the second quarter of 21st century, >>> the 80 should be left in 80s... >>> >>> (and yes, I deliberately put the above too short). >> >> I didn't even notice you had squeezed the lines :) >> >> But yeah, I truly have problems fitting even 3 80 column terminals on screen >> with my current monitor. And when working on laptop screen it becomes >> impossible. Hence I strongly prefer keeping the 80 chars limit. > > Maybe you need a bigger monitor after all? (lurking now :-) Wouldn't fit my table :) > ... > >>>>>> +#include >>>>> >>>>> I'm failing to see how this is being used in this header. >>>> >>>> I suppose it was the struct iio_chan_spec. Yep, forward declaration could >>>> do, but I guess there would be no benefit because anyone using this header >>>> is more than likely to use the iio.h as well. >>> >>> Still, it will be a beast to motivate people not thinking about what they are >>> doing. I strongly prefer avoiding the use of the "proxy" or dangling headers. >> >> Ehh. There will be no IIO user who does not include the iio.h. > > It's not your concern. That's the idea of making C units as much independent > and modular as possible (with common sense in mind). And in this case I see > no point of including this header. Again, the main problem is this will call > people to use the new header as a "proxy" and that's what I fully against to. > >> And, I need the iio_chan_spec here. > > Do you really need it or is it just a pointer? Just a pointer. Forward declaration could do it. Hmm. I didn't think of people using this header as a proxy. I guess you have a point here :) > > ... > >> And as I said, I suggest saving some of the energy for reviewing the next >> version. I doubt the "property type" -flags and bitwise operations stay, and >> it may be all of this will be just meld in the bd79124 code - depending on >> what Jonathan & others think of it. > > Whenever this code will be trying to land, the review comments still apply. Sure! But chances are plenty of this code gets erased :) I just wanted to warn you that some of the effort on this version is likely to get wasted. I did consider reverting this back to a RFC - but going back'n forth with the RFC status felt odd... Yours, -- Matti