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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 092E8C433E0 for ; Sun, 28 Feb 2021 15:04:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B63DE64EB1 for ; Sun, 28 Feb 2021 15:04:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230298AbhB1PEc convert rfc822-to-8bit (ORCPT ); Sun, 28 Feb 2021 10:04:32 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]:2613 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229715AbhB1PEc (ORCPT ); Sun, 28 Feb 2021 10:04:32 -0500 Received: from fraeml741-chm.china.huawei.com (unknown [172.18.147.206]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4DpRN35tl8z67qtQ; Sun, 28 Feb 2021 22:58:11 +0800 (CST) Received: from lhreml710-chm.china.huawei.com (10.201.108.61) by fraeml741-chm.china.huawei.com (10.206.15.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Sun, 28 Feb 2021 16:03:47 +0100 Received: from localhost (10.47.88.221) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Sun, 28 Feb 2021 15:03:47 +0000 Date: Sun, 28 Feb 2021 15:02:39 +0000 From: Jonathan Cameron To: Ronald =?ISO-8859-1?Q?Tschal=E4r?= CC: Jiri Kosina , Benjamin Tissoires , Jonathan Cameron , Srinivas Pandruvada , "Lars-Peter Clausen" , Peter Meerwald-Stadler , , , Subject: Re: [PATCH 4/5] HID: apple-ibridge: Add Apple iBridge HID driver for T1 chip. Message-ID: <20210228150239.00007d34@Huawei.com> In-Reply-To: <20210228012643.69944-5-ronald@innovation.ch> References: <20210228012643.69944-1-ronald@innovation.ch> <20210228012643.69944-5-ronald@innovation.ch> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8BIT X-Originating-IP: [10.47.88.221] X-ClientProxiedBy: lhreml718-chm.china.huawei.com (10.201.108.69) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org On Sat, 27 Feb 2021 17:26:42 -0800 Ronald Tschalär wrote: > The iBridge device provides access to several devices, including: > - the Touch Bar > - the iSight webcam > - the light sensor > - the fingerprint sensor > > This driver provides the core support for managing the iBridge device > and the access to the underlying devices. In particular, the > functionality for the touch bar and light sensor is exposed via USB HID > interfaces, and on devices with the T1 chip one of the HID devices is > used for both functions. So this driver creates virtual HID devices, one > per top-level report collection on each HID device (for a total of 3 > virtual HID devices). The sub-drivers then bind to these virtual HID > devices. > > This way the Touch Bar and ALS drivers can be kept in their own modules, > while at the same time making them look very much like as if they were > connected to the real HID devices. And those drivers then work (mostly) > without further changes on MacBooks with the T2 chip that don't need > this driver. > > Signed-off-by: Ronald Tschalär Hi Ronald. This is far from my specialty but mostly looks sensible to me. Just one thing stood out that I couldn't understand. See below. Jonathan > new file mode 100644 > index 0000000000000..5f2b71c199746 > --- /dev/null > +++ b/drivers/hid/apple-ibridge.c > @@ -0,0 +1,682 @@ ... > + > +#ifdef CONFIG_PM > +/** > + * appleib_forward_int_op() - Forward a hid-driver callback to all drivers on > + * all virtual HID devices attached to the given real HID device. > + * @hdev the real hid-device > + * @forward a function that calls the callback on the given driver > + * @args arguments for the forward function > + * > + * This is for callbacks that return a status as an int. > + * > + * Returns: 0 on success, or the first error returned by the @forward function. > + */ > +static int appleib_forward_int_op(struct hid_device *hdev, > + int (*forward)(struct hid_driver *, > + struct hid_device *, void *), > + void *args) > +{ > + struct appleib_hid_dev_info *hdev_info = hid_get_drvdata(hdev); > + struct hid_device *sub_hdev; > + int rc = 0; > + int i; > + > + for (i = 0; i < ARRAY_SIZE(hdev_info->sub_hdevs); i++) { > + sub_hdev = hdev_info->sub_hdevs[i]; > + if (sub_hdev->driver) { > + rc = forward(sub_hdev->driver, sub_hdev, args); > + if (rc) > + break; return rc; here would be cleaner. > + } > + > + break; This is unusual. It's a for loop but as far as I can see only first iteration can ever run as we exit the loop at this break if we haven't done so earlier. What is the intent here? > + } > + > + return rc; > +}