From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C74AC433FE for ; Fri, 11 Dec 2020 12:10:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4B0A12246B for ; Fri, 11 Dec 2020 12:10:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392014AbgLKMJj (ORCPT ); Fri, 11 Dec 2020 07:09:39 -0500 Received: from mail.kernel.org ([198.145.29.99]:51180 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389342AbgLKMJF (ORCPT ); Fri, 11 Dec 2020 07:09:05 -0500 Date: Fri, 11 Dec 2020 13:09:35 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1607688503; bh=41rS8U52qZEUqZ7Xg2L67KOIODeUL5vsHKWqEJrq3PY=; h=From:To:Cc:Subject:References:In-Reply-To:From; b=aHNI8D5uOwfHjKS+cWBLwZ0CjZq9PhyzDYeD/RKhSB8O2yaSz6s7CWRprq6HDrIpW Y/LGtZrskpkFmtyZmHNjERogoKuUR0fTZvICbxeWa297qH/ZHEZW32TNbugsC76gTP IEoWW4J62N7D8fqqEANDZScrAj6PO1FhFTvaLvyU= From: 'Greg Kroah-Hartman' To: =?iso-8859-1?Q?J=F3zsef_Horv=E1th?= Cc: 'Rob Herring' , 'Jiri Slaby' , linux-serial@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] Serial: silabs si4455 serial driver Message-ID: References: <20201210194625.GA17516@dincontrollerdev> <20201211060943.GA1065@dincontrollerdev> <20201211063752.GB1065@dincontrollerdev> <20201211081634.GC1065@dincontrollerdev> <20201211091823.GD1065@dincontrollerdev> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20201211091823.GD1065@dincontrollerdev> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 11, 2020 at 09:18:24AM +0000, József Horváth wrote: > On Fri, Dec 11, 2020 at 09:43:31AM +0100, 'Greg Kroah-Hartman' wrote: > > On Fri, Dec 11, 2020 at 08:16:34AM +0000, József Horváth wrote: > > > On Fri, Dec 11, 2020 at 08:33:17AM +0100, 'Greg Kroah-Hartman' wrote: > > > > On Fri, Dec 11, 2020 at 06:37:52AM +0000, József Horváth wrote: > > > > > On Fri, Dec 11, 2020 at 07:20:41AM +0100, 'Greg Kroah-Hartman' wrote: > > > > > > On Fri, Dec 11, 2020 at 06:09:43AM +0000, József Horváth wrote: > > > > > > > On Fri, Dec 11, 2020 at 06:50:58AM +0100, 'Greg Kroah-Hartman' wrote: > > > > > > > > On Thu, Dec 10, 2020 at 07:46:25PM +0000, József Horváth wrote: > > > > > > > > > On Thu, Dec 10, 2020 at 08:03:22PM +0100, 'Greg Kroah-Hartman' wrote: > > > > > > > > > > On Thu, Dec 10, 2020 at 05:04:46PM +0000, József Horváth wrote: > > > > > > > > > > > This is a serial port driver for > > > > > > > > > > > Silicon Labs Si4455 Sub-GHz transciver. > > > > > > > > > > > + > > > > > > > > > > > +#define BASE_TTYIOC_PRIVATE 0xA0 > > > > > > > > > > > +/* Set EZConfig. > > > > > > > > > > > + * After this ioctl call, the driver restarts the si4455, > > > > > > > > > > > + * then apply the new configuration and patch. > > > > > > > > > > > + */ > > > > > > > > > > > +#define SI4455_IOC_SEZC _IOW('T', \ > > > > > > > > > > > + BASE_TTYIOC_PRIVATE + 0x01, \ > > > > > > > > > > > + struct si4455_iocbuff) > > > > > > > > > > > > > > > > > > > > Why does a serial driver have private ioctls? Please no, don't do that. > > > > > > > > > > > > > > > > > > I checked the ioctl.h and serial_core.h, but I not found any similar definition, like BASE_VIDIOC_PRIVATE in videodev2.h. > > > > > > > > > In this case the name of macro BASE_TTYIOC_PRIVATE means the base value of special ioctl commands owned by this driver. > > > > > > > > > > > > > > > > My point is, a serial driver should NOT have any custom ioctls. > > > > > > > > > > > > > > > > > I can change it to BASE_TTYIOC or SI4455_IOC_BASE > > > > > > > > > > > > > > > > > > > Implement the basic serial driver first, and then we can talk about > > > > > > > > > > "custom" configurations and the like, using the correct apis. > > > > > > > > > > > > > > > > > > Without the SI4455_IOC_SEZC call, the driver can't configure the Si4455 and not working at all. > > > > > > > > > The cofiguration for interface is provided by user for application. > > > > > > > > > > > > > > > > That is what a device tree is for, to configure the device to have the > > > > > > > > correct system configuration, why can't that be the same here? > > > > > > > > > > > > > > > > > It contains the base frequency, channel spacing, modulation, and a lot > > > > > > > > > of more stuff, and generated by Silicon Labs Wireless Development > > > > > > > > > Suite. > > > > > > > > > The generated configuration is in a non public(compressed, > > > > > > > > > encrypted...who knows) format, so without this the driver can't > > > > > > > > > provide configuration parameters to Si4455. > > > > > > > > > > > > > > > > So we have to take a "custom" userspace blob and send it to the device > > > > > > > > to configure it properly? Like Jiri said, sounds like firmware, so just > > > > > > > > use that interface instead. > > > > > > > > > > > > > > I checked Jiri's suggestion, and it is a good solution to replace SI4455_IOC_SEZC(configuration) and SI4455_IOC_SEZP(firmware patch). > > > > > > > I can move SI4455_IOC_SSIZ(package size) to device tree property. > > > > > > > > > > > > > > Maybe you have good suggestion for the following: > > > > > > > SI4455_IOC_STXC -> Radio transmit channel index. It is a real use case to control this parameter by user at runtime. > > > > > > > SI4455_IOC_SRXC -> Radio receive channel index. It is a real use case to control this parameter by user at runtime. > > > > > > > > > > > > These are not serial port things, why would a serial port care about > > > > > > these? > > > > > > > > > > You are right, these are not regular serial port things, but this device is not a regular uart, it is a sub-GHz transciever, digital radio. > > > > > This driver tries to represent it as a serial port to user. > > > > > > > > Is that the correct representation to be using here? Why not act like a > > > > proper radio device instead? That way you get to use the normal kernel > > > > apis for radio devices. > > > > > > In my mind it is absolute a serial device by the application. > > > > What is the application? Traditionally serial ports don't need radio signals :) > > The application is connecting newly developed sensors(with only rf interface) and legacy sensors(with regular serial communication over rs-485 with modbus) keeping the legacy user software. > > User sw [Java] > <-> /dev/ttyXXX > <-> si4455[driver] > <-> si4455[hardware] > <---air---> new device[si4455+ARM Cortex-M0] 1 > +-> new device[si4455+ARM Cortex-M0] 2 > +-> new device[si4455+ARM Cortex-M0] n > +-> gateway[si4455+ARM Cortex-M0]<---RS485--> Legacy device 1 > +-> Legacy device 2 > +-> Legacy device n If these are "sensors", why are you using a tty interface at all, and not just using the correct iio interface for them? thanks, greg k-h