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[209.132.180.67]) by mx.google.com with ESMTP id h129si1608009pfb.253.2018.12.29.09.52.35; Sat, 29 Dec 2018 09:52:52 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728803AbeL2G3B (ORCPT + 99 others); Sat, 29 Dec 2018 01:29:01 -0500 Received: from mx2.suse.de ([195.135.220.15]:44700 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726672AbeL2G3A (ORCPT ); Sat, 29 Dec 2018 01:29:00 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id C0B8EAD8F; Sat, 29 Dec 2018 06:28:56 +0000 (UTC) Subject: Re: [PATCH v5 6/6] net: lorawan: List LORAWAN in menuconfig To: Alexander Aring Cc: Xue Liu , Jian-Hong Pan , "David S . Miller" , Alan Cox , linux-lpwan@lists.infradead.org, netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Marcel Holtmann , Dollar Chen , Ken Yu , linux-wpan - ML , Jiri Pirko , Stefan Schmidt References: <20181216101858.9585-7-starnight@g.ncu.edu.tw> <8bfdccbf-fb47-daa5-fbd0-ed16a3d6d334@suse.de> <20181224153205.ycr2zdrjbyklulfh@x220t> <57bead63-bc4e-4dfe-57a9-9875600f5e37@suse.de> <20181228154316.2x2tyfzidnb4emqo@x220t> From: =?UTF-8?Q?Andreas_F=c3=a4rber?= Openpgp: preference=signencrypt Autocrypt: addr=afaerber@suse.de; prefer-encrypt=mutual; keydata= xsFNBE6W6ZQBEAC/BIukDnkVenIkK9O14UucicBIVvRB5WSMHC23msS+R2h915mW7/vXfn+V 0nrr5ECmEg/5OjujKf0x/uhJYrsxcp45nDyYCk+RYoOJmGzzUFya1GvT/c04coZ8VmgFUWGE vCfhHJro85dZUL99IoLP21VXEVlCPyIngSstikeuf14SY17LPTN1aIpGQDI2Qt8HHY1zOVWv iz53aiFLFeIVhQlBmOABH2Ifr2M9loRC9yOyGcE2GhlzgyHGlQxEVGFn/QptX6iYbtaTBTU0 c72rpmbe1Nec6hWuzSwu2uE8lF+HYcYi+22ml1XBHNMBeAdSEbSfDbwc///8QKtckUzbDvME S8j4KuqQhwvYkSg7dV9rs53WmjO2Wd4eygkC3tBhPM5s38/6CVGl3ABiWJs3kB08asUNy8Wk juusU/nRJbXDzxu1d+hv0d+s5NOBy/5+7Pa6HeyBnh1tUmCs5/f1D/cJnuzzYwAmZTHFUsfQ ygGBRRKpAVu0VxCFNPSYKW0ULi5eZV6bcj+NAhtafGsWcv8WPFXgVE8s2YU38D1VtlBvCo5/ 0MPtQORqAQ/Itag1EHHtnfuK3MBtA0fNxQbb2jha+/oMAi5hKpmB/zAlFoRtYHwjFPFldHfv Iljpe1S0rDASaF9NsQPfUBEm7dA5UUkyvvi00HZ3e7/uyBGb0QARAQABzSJBbmRyZWFzIEbD pHJiZXIgPGFmYWVyYmVyQHN1c2UuZGU+wsF7BBMBAgAlAhsDBgsJCAcDAgYVCAIJCgsEFgID AQIeAQIXgAUCTqGJnQIZAQAKCRD6LtEtPn4BPzetD/4rF6k/HF+9U9KqykfJaWdUHJvXpI85 Roab12rQbiIrL4hVEYKrYwPEKpCf+FthXpgOq+JdTGJ831DMlTx7Ed5/QJ9KAAQuhZlSNjSc +FNobJm7EbFv9jWFjQC0JcOl17Ji1ikgRcIRDCul1nQh9jCdfh1b848GerZmzteNdT9afRJm 7rrvMqXs1Y52/dTlfIW0ygMA2n5Vv3EwykXJOPF6fRimkErKO84sFMNg0eJV9mXs+Zyionfi g2sZJfVeKjkDqjxy7sDDBZZR68I9HWq5VJQrXqQkCZUvtr6TBLI+uiDLbGRUDNxA3wgjVdS2 v9bhjYceSOHpKU+h3H2S8ju9rjhOADT2F5lUQMTSpjlzglh8IatV5rXLGkXEyum4MzMo2sCE Cr+GD6i2M3pHCtaIVV3xV0nRGALa6DdF7jBWqM54KHaKsE883kFH2+6ARcPCPrnPm7LX98h2 4VpG984ysoq6fpzHHG/KCaYCEOe1bpr3Plmmp3sqj0utA6lwzJy0hj5dqug+lqmg7QKAnxl+ porgluoY56U0X0PIVBc0yO0dWqRxtylJa9kDX/TKwFYNVddMn2NQNjOJXzx2H9hf0We7rG7+ F/vgwALVVYbiTzvp2L0XATTv/oX4BHagAa/Qc3dIsBYJH+KVhBp+ZX4uguxk4xlc2hm75b1s cqeAD87BTQROlumUARAAzd7eu+tw/52FB7xQZWDv5aF+6CAkoz7AuY4s1fo0AQQDqjLOdpQF bifdH7B8SnsA4eo0syfs+1tZW6nn9hdy1GHEMbeuvdhNwkhEfYGDYpSue7oVxB4jajKvRHAP VcewKZIxvIiZ5aSp5n1Bd7B0c0C443DHiWE/0XWSpvbU7fTzTNvdz+2OZmGtqCn610gBqScv 1BOiP3OfLly8ghxcJsos23c0mkB/1iWlzh3UMFIGrzsK3sZJ/3uRaLYFimmqqPlSwFqx3b0M 1gFdHWKfOpvQ4wwP5P10xwvqNXLWC30wB1QmJGD/X8aAoVNnGsmEL7GcWF4cLoOSRidSoccz znShE+Ap+FVDD6MRyesNT4D67l792//B38CGJRdELtNacdwazaFgxH9O85Vnd70ZC7fIcwzG yg/4ZEf96DlAvrSOnu/kgklofEYdzpZmW+Fqas6cnk6ZaHa35uHuBPesdE13MVz5TeiHGQTW xP1jbgWQJGPvJZ+htERT8SZGBQRb1paoRd1KWQ1mlr3CQvXtfA/daq8p/wL48sXrKNwedrLV iZOeJOFwfpJgsFU4xLoO/8N0RNFsnelBgWgZE3ZEctEd4BsWFUw+czYCPYfqOcJ556QUGA9y DeDcxSitpYrNIvpk4C5CHbvskVLKPIUVXxTNl8hAGo1Ahm1VbNkYlocAEQEAAcLBXwQYAQIA CQUCTpbplAIbDAAKCRD6LtEtPn4BPzA6D/9TbSBOPM99SHPX9JiEQAw4ITCBF2oTWeZQ6RJg RKpB15lzyPfyFbNSceJp9dCiwDWe+pzKaX6KYOFZ5+YTS0Ph2eCR+uT2l6Mt6esAun8dvER/ xlPDW7p88dwGUcV8mHEukWdurSEDTj8V3K29vpgvIgRq2lHCn2wqRQBGpiJAt72Vg0HxUlwN GAJNvhpeW8Yb43Ek7lWExkUgOfNsDCTvDInF8JTFtEXMnUcPxC0d/GdAuvBilL9SlmzvoDIZ 5k2k456bkY3+3/ydDvKU5WIgThydyCEQUHlmE6RdA3C1ccIrIvKjVEwSH27Pzy5jKQ78qnhv dtLLAavOXyBJnOGlNDOpOyBXfv02x91RoRiyrSIM7dKmMEINKQlAMgB/UU/6B+mvzosbs5d3 4FPzBLuuRz9WYzXmnC460m2gaEVk1GjpidBWw0yY6kgnAM3KhwCFSecqUQCvwKFDGSXDDbCr w08b3GDk40UoCoUq9xrGfhlf05TUSFTg2NlSrK7+wAEsTUgs2ZYLpHyEeftoDDnKpM4ghs/O ceCeyZUP1zSgRSjgITQp691Uli5Nd1mIzaaM8RjOE/Rw67FwgblKR6HAhSy/LYw1HVOu+Ees RAEdbtRt37A8brlb/ENxbLd9SGC8/j20FQjit7oPNMkTJDs7Uo2eb7WxOt5pSTVVqZkv7Q== Organization: SUSE Linux GmbH Message-ID: <5c3c9f71-73f3-6010-04c3-75ac91a35b05@suse.de> Date: Sat, 29 Dec 2018 07:28:53 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: <20181228154316.2x2tyfzidnb4emqo@x220t> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 28.12.18 um 16:43 schrieb Alexander Aring: > On Fri, Dec 28, 2018 at 05:57:53AM +0100, Andreas Färber wrote: >> Am 24.12.18 um 16:32 schrieb Alexander Aring: >>> On Tue, Dec 18, 2018 at 02:50:58PM +0100, Xue Liu wrote: >>>> On Mon, 17 Dec 2018 at 15:19, Andreas Färber wrote: >>>>> Am 17.12.18 um 09:50 schrieb Xue Liu: >>>>>> I have a question about the architecture of your module. AFAIK LoRaWAN >>>>>> is already the MAC Layer above the LoRa technology. Why do you want to >>>>>> make a new layer called "maclorawan" ? >>>>> >>>>> I had asked Jian-Hong to separate between his soft-MAC implementation >>>>> and the common bits needed to drive hard-MAC implementations found on >>>>> several of the hardware modules made available to me. >>>>> >>>> As a reference Linux 802.11 uses cfg80211 to talk with hard-MAC devices. >>>> We may also use the name “cfglora” for hard-MAC implementation. >>> >>> There exists also a cfg802154. :-) >>> >>> Note that cfg80211 is also for providing a backwardscompatibility to the >>> wireless ioctl() interface. >>> >>> In theory it's simple: >>> >>> netlink API -> SoftMAC (macFOOBAR layer) -> cfgFOOBAR implementation -> driver layer >>> \-> HardMAC (driver layer) -> cfgFOOBAR implementation >> >> So how does cfgFOOBAR relate to nlFOOBAR now? Given that we were told to >> use netlink and pointed to some nl802whatever, I am confused about two >> people now calling for cfg. We have an nllora stubbed in linux-lora.git, >> and I was expecting to see an nllorawan¹ either in this series or on > > Why there is a different between two lora technologies? This sounds you > driving into two lora subsystems without one userspace api to access them, > this getting worse. This had just been explained to Jiri: LoRa PHY vs. LoRaWAN MAC. Similar splits exist for other technologies; and how the LoRaWAN soft-MAC can reuse underlying LoRa facilities is the very subject of this sub-thread! It entirely depends on what the user wants to do - connect to a LoRaWAN network as client, forward LoRaWAN packets as a gateway, communicate peer-to-peer, implement alternative MACs in userspace, ... So if a user is working on LoRaWAN MAC layer I expect him to deal with PF_LORAWAN and nllorawan and not need direct access to nllora, as that would be an implementation detail specific to the soft-MAC; a hard-MAC should not need to implement nllora, as it may not have that control. >> top. If you're suggesting to rename them technology-neutral, then please > > I am sorry, I actually meant that... People tell me that I can't explain > things all the time. > >> say so clearly - otherwise it sounds to me like you didn't actually look >> at the staged code yet or didn't read our previous discussions and lead >> our contributors to reinvent things we already have... > > As example for 802.15.4: > > nl802154 (which is one netlink interface for doesn't matter what > kind 802.15.4 device is behind) -> callback structure of cfg802154 which > goes to a somehow 802.15.4 device as SoftMAC layer or HardMAC driver. Okay, I took a shortcut there for LoRa and assume we always have a LoRa netdev (i.e., no theoretical SDR netdev), so that I could postpone figuring out how to register extra per-netdev cfg structs for quicker PoC of the netlink interface. :) My get_freq callback will need to be moved out from struct lora_dev_priv (lora/netdev.h) into its own struct. >> We really need to complete the layers from the ground up before we get >> lost in more nice-to-have upper layers: For LoRaWAN that means we need >> to have TX and RX working for LoRa _and_ FSK. sx1276 still has lots of >> hardcoded stuff from my own testing that needs to hook into nllora, and >> FSK exists only as ETH_P_FSK constant so far, with no concept for >> switching modes yet (which as mentioned in my presentation¹ needs to go >> via sleep mode, losing most register settings) nor any netlink support. >> Not all drivers need to be at the same implementation level, of course, >> but we need at least one that's far enough to validate such patches. > > Your register behaviour sounds for me like a feature for regmap. Or > either a feature to handle in your subsystem. We don't have regmap caching enabled. sx1276 has no paging implemented, as it's slightly more complicated than sx1301 (and the "youngest" of 3). I assume instead of just writing from netlink/cfg callbacks to regmap we'll need to also save the values in the driver for writing them back after a mode switch or suspend. However it's also a question of who initiates the mode switch and how, presumably via netlink. >> And seeing that I just found a major bug in sx1276 driver's TX path, >> apparently no one apart from me is testing that driver - sx128x and >> sx1301 were not yet complete enough to transmit, and due to the open >> socket address/protocol discussions none can receive yet, so as Jiri >> hinted, this LoRaWAN soft-MAC patch series can't have been >> runtime-tested against any staged driver at all! => [RFC lora-next v5 6/6] > > aha. When I started working on ieee802154 many times I thought nobody > had really tested it. That's somehow the process of upstream > programming, it's growing over the time. The first implementation is > always somehow crappy, but people working on it and get experience over > the time, you cannot have perfect code. This is not about iterative development, it's about discussing about a high-level cfg interface on top of nl on top of a PHY that didn't work; not just some optional offload feature being broken. ;) We may never have perfect code, but we can't merge a driver that doesn't work at all, and as long as I know it's not working sufficiently I am holding back on sending out a v2, in favor of queuing more fixes and cleanups that'll make it worth people's time to review. Having the soft-MAC be further implemented and actually using the functions it implements may avoid some of the declarations Jiri disliked by just making them static locally where they're needed. Earlier reviewers were already getting deep into coding style reviews, but it seems this is not yet a "PATCH" ready for merging after all and should therefore by its author be labeled "RFC" or at least "RFT" if it couldn't be tested yet. If it's a "PATCH", I expect to be able to queue it on my tree if I spot no major design problems or nits the author could help fix upfront. Compare below. >> Therefore I thought in our case some hard-MAC may be easier to validate >> LoRaWAN sockets (patch 1/6), to avoid a dependency on completing the MAC >> implementation first. For example, iM880, RF1276TS and 32001353 are pure >> LoRaWAN modules without raw LoRa support. (Whereas many others support >> both and I'm still looking for input on how to best deal with that - >> currently exposing them as LoRa devices for maximal flexibility.) > > So that means you ignore SoftMAC because HardMAC is easier? No, I don't ignore it, I'm missing infrastructure to evaluate it! As Jiri has pointed out earlier, this series is doing two things, 1) introduce LoRaWAN sockets (that's great, needs review/discussion) and 2) prepare a soft-MAC implementation with a number of functions that are not yet called from anywhere. Plus the series omits to extend my lower-level netlink interfaces and driver(s) with the facilities it'll need to actually work. The default Sync Word on sx1276 is 0x12, for instance. Basically Jian-Hong and I are at odds in which direction the layers should plug together, with me vehemently against coding LoRaWAN stuff in LoRa drivers (layering violation!) and instead wanting that centrally in an optional LoRaWAN soft-MAC module (=maclorawan) on top. Compare 2/6 still reading "driver should implement some of them according to the usage" - for me that should be a cfg struct at the nllorawan layer, which he should implement in maclorawan and I only for hard-MAC drivers, instead of exporting an ABI that's not called by anyone and would seemingly need to be reimplemented in each and every of my LoRa drivers! Note that duplicate copies and forks of LoRaWAN soft-MAC userspace implementations on GitHub were one of the reasons for me to start this kernel project, so I really, really don't want that here. And 5/6 main.c appears to still be based around the idea that he gets his own loraX netdevs, seemingly conflicting by name with mine if they would actually get created by the functions getting called anywhere... Maybe you can now grasp my annoyance with this non-RFC v5 making only cosmetic changes since v2? (and completely lacking any changelog in 0/6) > We actually > go the opposite way to say SoftMAC introduce the most infrastructure and > then say that we will bind HardMAC to it. The very definition of a hard-MAC is that it does not need a soft-MAC. So that doesn't make much sense to me. The netlink interfaces for LoRa (e.g., Join operations for authentication) will be constrained by what ops the hard-MACs need, whereas we have much more freedoms with our own soft-MAC. LoRaWAN provides a meta set of operations compared to LoRa+FSK (e.g., setting the data rate on MAC layer would involve regional awareness and translates to setting frequency+bandwidth+SF on PHY layer, and a LoRa transmission/reception will need to set a Sync Word of 0x34); therefore my saying that for the soft-MAC we need interfaces and implementations on my LoRa PHY layer that are still incomplete today. Once the PHY layer is working, the soft-MAC would just need to properly dispatch - and ideally I would have it provide packets in an ETH_P_LORA format, so that I don't need duplicate (ETH_P_LORA + ETH_P_LORAWAN) implementations in each soft-MAC capable LoRa driver. Thus, if the PHY doesn't transmit (yet), LoRaWAN can't send either. And that brings us back to the big question circling since months of how to design these socket layers: Currently I'm using a PF_LORA and was hoping to extend its sock_addr to cope with the Sync Word, frequency, etc. and set that via skb for each TX (which raised problems for RX). At ELCE 2018 it was suggested that we should rather take the easy route of not defining a PF_LORA and just use PF_PACKET with htons(ETH_P_LORA) and apply every global setting via netlink; that however appears to obsolete my lora/dgram.c code dealing with private ifindex field then, so that we could no longer pass any LoRa-specific per-packet metadata from LoRaWAN layer down to LoRa either. And since I'm unfamiliar with PF_PACKET, I'm focusing on making the basics work first before diving into refactorings that give us no functional benefits. Anyway, I assume we'll need to translate from LoRaWAN to LoRa skbs somewhere in this patch series to add the necessary LoRaWAN headers for SOCK_DGRAM or SOCK_SEQPACKET packets - it's neither in 1/6 nor in 5/6. Additionally, operations such as Join that the user would request via netlink command will need to create LoRa skbs in the soft-MAC directly. So in that way LoRaWAN may be comparable to Wifi connecting to an AP, whereas LoRa is more like shoveling packets into/out an Ethernet cable. Hope that explains better from my side as well. Most of it had been brought up in replies to the cover letter of my original RFC on netdev list: https://patchwork.ozlabs.org/cover/937545/ Regards, Andreas -- SUSE Linux GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany GF: Felix Imendörffer, Jane Smithard, Graham Norton HRB 21284 (AG Nürnberg)