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[23.128.96.18]) by mx.google.com with ESMTP id o18si6051728edv.5.2021.04.28.07.52.50; Wed, 28 Apr 2021 07:53:15 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@foss.st.com header.s=selector1 header.b=3dlIO9+O; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=foss.st.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239662AbhD1NGM (ORCPT + 99 others); Wed, 28 Apr 2021 09:06:12 -0400 Received: from mx07-00178001.pphosted.com ([185.132.182.106]:43000 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239737AbhD1NGL (ORCPT ); Wed, 28 Apr 2021 09:06:11 -0400 Received: from pps.filterd (m0241204.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 13SD0j1f020977; Wed, 28 Apr 2021 15:05:23 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foss.st.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=selector1; bh=eVG3v1lNK3BXxdqTip+oyLR1+X82jhyNevCxSbpxH+E=; b=3dlIO9+Oshqkwmw+9VEIpjnuaax+TOlu3qUw838yVD7R1hhvpXJvuQirqC511+ByiqEr 5Wh3sCxTTDapgtXZW4IaTj4I1ULReLwAADx7L4e4hEAk08hQu5dtl5Vxa+GcJSeS/eu0 /oXJ+oSJop6N2+29FLAtxYWyJbHh6YM0Hn7oYNWCJmWqFnZIlSaNrqnbFPa5KeQ5AVdU Wf1c4eEnedbVh6DTWgtmragIddZ2udmLX1uqu+4fyTKYSgVvRJmppDFFC8k67PYXi99p Y4g6cgi7x8OrQe3PuKYUaYelcqe+9g7KGrn/HVRUWiL30ERGZlkyxptj85I31LS7ZzOQ EA== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com with ESMTP id 386ea8gghc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 28 Apr 2021 15:05:23 +0200 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 3022510002A; Wed, 28 Apr 2021 15:05:23 +0200 (CEST) Received: from Webmail-eu.st.com (sfhdag2node3.st.com [10.75.127.6]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 1BE06210895; Wed, 28 Apr 2021 15:05:23 +0200 (CEST) Received: from lmecxl0889.lme.st.com (10.75.127.51) by SFHDAG2NODE3.st.com (10.75.127.6) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 28 Apr 2021 15:05:22 +0200 Subject: Re: [PATCH v2 5/7] rpmsg: char: Introduce a rpmsg driver for the rpmsg char device To: Mathieu Poirier CC: Bjorn Andersson , Ohad Ben-Cohen , , , References: <20210413134458.17912-1-arnaud.pouliquen@foss.st.com> <20210413134458.17912-6-arnaud.pouliquen@foss.st.com> <20210421174053.GA1223348@xps15> <47015357-b006-1c32-f63f-d4fcac054d6f@foss.st.com> <20210422163622.GC1256950@xps15> From: Arnaud POULIQUEN Message-ID: <14998d88-b27b-3548-e52f-eb0365caa96f@foss.st.com> Date: Wed, 28 Apr 2021 15:05:21 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210422163622.GC1256950@xps15> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.75.127.51] X-ClientProxiedBy: SFHDAG1NODE2.st.com (10.75.127.2) To SFHDAG2NODE3.st.com (10.75.127.6) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-04-28_06:2021-04-27,2021-04-28 signatures=0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 4/22/21 6:36 PM, Mathieu Poirier wrote: > On Thu, Apr 22, 2021 at 09:58:27AM +0200, Arnaud POULIQUEN wrote: >> On 4/21/21 7:40 PM, Mathieu Poirier wrote: >>> Good day Arnaud, >>> >>> On Tue, Apr 13, 2021 at 03:44:56PM +0200, Arnaud Pouliquen wrote: >>>> A rpmsg char device allows to probe the endpoint device on a remote name >>>> service announcement. >>>> >>>> With this patch the /dev/rpmsgX interface is created either by a user >>>> application or by the remote firmware. >>>> >>>> Signed-off-by: Arnaud Pouliquen >>>> >>>> --- >>>> update from V1: >>>> - add missing unregister_rpmsg_driver call on module exit. >>>> >>>> --- >>>> drivers/rpmsg/rpmsg_char.c | 59 +++++++++++++++++++++++++++++++++++++- >>>> 1 file changed, 58 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c >>>> index a64249d83172..4606787b7011 100644 >>>> --- a/drivers/rpmsg/rpmsg_char.c >>>> +++ b/drivers/rpmsg/rpmsg_char.c >>>> @@ -26,6 +26,8 @@ >>>> #include "rpmsg_char.h" >>>> #include "rpmsg_internal.h" >>>> >>>> +#define RPMSG_CHAR_DEVNAME "rpmsg-raw" >>>> + >>> >>> Why not simply call it rpmsg-char? >> >> I would avoid to link the rpmsg name service to the Linux Kernel device. > > To me that's exactly what we want to do... Am I missing something? > >> >>> >>>> static dev_t rpmsg_major; >>>> >>>> static DEFINE_IDA(rpmsg_ept_ida); >>>> @@ -403,13 +405,67 @@ int rpmsg_chrdev_create_eptdev(struct rpmsg_device *rpdev, struct device *parent >>>> } >>>> EXPORT_SYMBOL(rpmsg_chrdev_create_eptdev); >>>> >>>> +static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev) >>>> +{ >>>> + struct rpmsg_channel_info chinfo; >>>> + struct rpmsg_eptdev *eptdev; >>>> + >>>> + if (!rpdev->ept) >>>> + return -EINVAL; >>>> + >>>> + memcpy(chinfo.name, RPMSG_CHAR_DEVNAME, sizeof(RPMSG_CHAR_DEVNAME)); >>>> + chinfo.src = rpdev->src; >>>> + chinfo.dst = rpdev->dst; >>>> + >>>> + eptdev = __rpmsg_chrdev_create_eptdev(rpdev, &rpdev->dev, chinfo, NULL); >>>> + if (IS_ERR(eptdev)) >>>> + return PTR_ERR(eptdev); >>>> + >>>> + /* Set the private field of the default endpoint to retrieve context on callback. */ >>>> + rpdev->ept->priv = eptdev; >>> >>> This is already done in rpmsg_create_ept() when rpmsg_eptdev_open() is called. >>> >>>> + >>>> + return 0; >>>> +} >>>> + >>>> +static void rpmsg_chrdev_remove(struct rpmsg_device *rpdev) >>>> +{ >>>> + int ret; >>>> + >>>> + ret = device_for_each_child(&rpdev->dev, NULL, rpmsg_chrdev_destroy_eptdev); >>>> + if (ret) >>>> + dev_warn(&rpdev->dev, "failed to destroy endpoints: %d\n", ret); >>>> +} >>>> + >>>> +static struct rpmsg_device_id rpmsg_chrdev_id_table[] = { >>>> + { .name = RPMSG_CHAR_DEVNAME }, >>>> + { }, >>>> +}; >>>> + >>>> +static struct rpmsg_driver rpmsg_chrdev_driver = { >>>> + .probe = rpmsg_chrdev_probe, >>>> + .remove = rpmsg_chrdev_remove, >>>> + .id_table = rpmsg_chrdev_id_table, >>>> + .callback = rpmsg_ept_cb, >>> >>> Not sure why we need a callback associated to this driver when >>> rpmsg_eptdev_open() already creates and rpmsg_endpoint. To me the only thing >>> having a callback provides is the association between the rpmsg_device and the >>> rpmsg_endpoint[1] that happens in rpmsg_dev_probe(). The QC folks already do >>> this association in their platform code[2]. Since this is not done in >>> __rpmsg_create_ept() a check for rpdev->ept == NULL could be done in >>> rpmsg_eptdev_open() and do the assignment there. >>> >>> [1]. https://elixir.bootlin.com/linux/v5.12-rc6/source/drivers/rpmsg/rpmsg_core.c#L513 >>> [2]. https://elixir.bootlin.com/linux/v5.12-rc6/source/drivers/rpmsg/qcom_glink_native.c#L1623 >>> >> >> That's a good point! When I started the redesign, I faced some issues with the >> approach you propose. But as I can not remember the reason and because the code >> has evolved, i need to re-think about this. >> > > Glad to see we're on the same page. I stared at this code for a very long time, > thinking there was some kind of bigger picture I wasn't getting. I finally found the time to investigate this. If I remember now why I used this approach, I also saw that my patchset does not work with the QCOM platform driver. As a first step of explanation, let's ignore the QC platform. rpdev->ept is null for the rpmsg ctrldev device created by the virtio rpmsg bus. If no default endpoint is created on rpmsg_chrdev_probe, it is not possible to differentiate the two in rpmsg_eptdev_open based on rpdev->ept == NULL. Now let's add the QC implementation As you mentioned, QC sets the rpdev->ept to a default endpoint before registering the rpmsg ctrldev. This shows that it is not reasonable to expect to handle all use cases based on the rpdev->ept value. So, to summarize, I need to rework this, probably by adding a new field in the rpmsg_eptdev structure, to properly handle the endpoint creation in the rpmsg_eptdev_open function. Regards, Arnaud > > >> Thanks, >> Arnaud >> >> >>>> + .drv = { >>>> + .name = "rpmsg_chrdev", >>>> + }, >>>> +}; >>>> + >>>> static int rpmsg_chrdev_init(void) >>>> { >>>> int ret; >>>> >>>> ret = alloc_chrdev_region(&rpmsg_major, 0, RPMSG_DEV_MAX, "rpmsg_char"); >>>> - if (ret < 0) >>>> + if (ret < 0) { >>>> pr_err("rpmsg: failed to allocate char dev region\n"); >>>> + return ret; >>>> + } >>>> + >>>> + ret = register_rpmsg_driver(&rpmsg_chrdev_driver); >>>> + if (ret < 0) { >>>> + pr_err("rpmsg: failed to register rpmsg raw driver\n"); >>>> + unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX); >>>> + } >>>> >>>> return ret; >>>> } >>>> @@ -417,6 +473,7 @@ postcore_initcall(rpmsg_chrdev_init); >>>> >>>> static void rpmsg_chrdev_exit(void) >>>> { >>>> + unregister_rpmsg_driver(&rpmsg_chrdev_driver); >>>> unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX); >>>> } >>>> module_exit(rpmsg_chrdev_exit); >>>> -- >>>> 2.17.1 >>>>