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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 6DC86C07E85 for ; Wed, 14 Nov 2018 07:51:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3DEC3223DD for ; Wed, 14 Nov 2018 07:51:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3DEC3223DD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=holtmann.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731861AbeKNRxZ convert rfc822-to-8bit (ORCPT ); Wed, 14 Nov 2018 12:53:25 -0500 Received: from coyote.holtmann.net ([212.227.132.17]:60764 "EHLO mail.holtmann.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725907AbeKNRxZ (ORCPT ); Wed, 14 Nov 2018 12:53:25 -0500 Received: from marcel-macbook.fritz.box (p4FF9F655.dip0.t-ipconnect.de [79.249.246.85]) by mail.holtmann.org (Postfix) with ESMTPSA id 6EC98CEEAF; Wed, 14 Nov 2018 08:58:48 +0100 (CET) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 12.1 \(3445.101.1\)) Subject: Re: [Letux-kernel] [PATCH RFC] bluetooth: add uart h4 devices via serdev/devicetree From: Marcel Holtmann In-Reply-To: <20181113170128.0f59ef0e@kemnade.info> Date: Wed, 14 Nov 2018 08:51:17 +0100 Cc: Rob Herring , sebastian.reichel@collabora.com, hns@goldelico.com, devicetree@vger.kernel.org, Johan Hedberg , Linux Kernel Mailing List , linux-bluetooth@vger.kernel.org, letux-kernel@openphoenux.org Content-Transfer-Encoding: 8BIT Message-Id: <86A3A2E6-FC89-42FE-8410-9C8273EC9CF7@holtmann.org> References: <20181110232034.17277-1-andreas@kemnade.info> <20181111024648.7rt7rlhaqihtqecv@earth.universe> <20181112215812.18ebca35@aktux> <2C74C837-A6D3-47C9-BE59-CCA594289B94@goldelico.com> <20181112222726.73m2oca7hankvcjs@earth.universe> <20181113170128.0f59ef0e@kemnade.info> To: Andreas Kemnade X-Mailer: Apple Mail (2.3445.101.1) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Andreas, >>>>> Am 12.11.2018 um 21:59 schrieb Andreas Kemnade : >>>>> On Sun, 11 Nov 2018 03:46:48 +0100 >>>>> Sebastian Reichel wrote: >>>>>> On Sun, Nov 11, 2018 at 12:20:34AM +0100, Andreas Kemnade wrote: >>>>>>> This is a first try to be able to use h4 devices specified in >>>>>>> the devicetree, so you do not need to call hciattach and >>>>>>> it can be automatically probed. >>>>>>> >>>>>>> Of course, proper devicetree bindings documentation is >>>>>>> missing. And also you would extend that by regulator/ >>>>>>> enable gpio settings. >>>>>>> >>>>>>> But before proceeding further it should be checked if the >>>>>>> general way of doing things is right. >>>>>>> >>>>>>> Signed-off-by: Andreas Kemnade >>>>>>> --- >>>>>> >>>>>> Patch looks good to me, just one note >>>>>> >>>>> I found one thing myself: >>>>> Shouldn't we have a generic compatible string like "generic-h4". >>>>> ehci-platform.c has for example: >>>>> { .compatible = "generic-ehci", }, >>>> >>>> There might be differences in h4 compatible devices (e.g. default >>>> baud rate) so that I would not bet there a "generic-h4" suffices >>>> in the long run. >> >> It will not because that doesn't define clocks, resets, gpios, >> supplies, etc. and the interactions of all those. >> > well, we need a simple supply being on when the device is on. > Nothing more. > >>> My suggestion is to use this in DT: >>> >>> compatible = "wi2wi,w2cbw003-bluetooth", ""; >>> > That would be my slight preference here. > >>> The driver can start with supporting just the generic compatible >>> string. If somebody finds some incompatible differences, the driver >>> can add a custom handler for the wi2wi chip without breaking DT >>> ABI. >> >> Any idea how many H4 devices there are? Somehow I doubt there are that >> many to be unmanageable. >> > Well, many devices are h4 devices with some more or less important > vendor-specific commands. Well, "hciattach any" uses simple h4 protocol. > > those firmware download commands and they have their own drivers. > Most devices I had used bluetooth uart from the command line with, were > simple enough. The other question is whether those devices will run a > modern kernel. > > No strong opinion here. doing the firmware load from user space via some magic tool is no longer going to work smoothly. It will be actually almost impossible with serdev. However I did post btuart.c driver which is pretty much just plain H:4. You would still somehow define the default baudraute since just picking 115200 is not always going to work. Btw. I see nothing standing in the way of merging btuart.c driver and then go from there. Either I dig this out and submit or someone else does. Regards Marcel