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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 25E0DC433EF for ; Tue, 30 Nov 2021 14:45:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242331AbhK3Osb (ORCPT ); Tue, 30 Nov 2021 09:48:31 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:22370 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235434AbhK3Osa (ORCPT ); Tue, 30 Nov 2021 09:48:30 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1638283511; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=N/D4Uh2tQePJy9ISUxPytT0nz40Sq7tw+TN3bITgjmE=; b=a1Tpq51B3rWmi0FOuHhYcz7YPxbgsAqOgD8aHPELR6x0HT3UDucNZauTsnn9I04TbMafgJ O6B5NTtnCuNo/02yNF8cKx7jFapPbguc//QG2O9+K7flGakPfb5G218JJT/DoSGtp+Efdn bDHH4fbO5pOS52UnTvo69VVpbVcSxXE= Received: from mail-pj1-f72.google.com (mail-pj1-f72.google.com [209.85.216.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-371-zjFMEXhYMTyy-JDKsWPrdA-1; Tue, 30 Nov 2021 09:45:08 -0500 X-MC-Unique: zjFMEXhYMTyy-JDKsWPrdA-1 Received: by mail-pj1-f72.google.com with SMTP id x6-20020a17090a6c0600b001a724a5696cso9925164pjj.6 for ; Tue, 30 Nov 2021 06:45:08 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=N/D4Uh2tQePJy9ISUxPytT0nz40Sq7tw+TN3bITgjmE=; b=SzfmyRaILVaqgIvVNikCCK8Ekych7rQ7TzWqz95y+DcPDPzQvQuqRG/vdYrWRefp7v vxLoiwYlAWo3fhaev1xP04FCy8y+9fsZUr2Bu9RAexjqBDfxuPsAX773UqiNfhpFnk2n 6FVLIk/ACSiCaK8ktiUE87xqMTC7++xcbM3rnslHVpF+SpFzi5tUBpAI2H3MrsVwtbRG Ky+CY915nglWIkGt8+aRnMwDOK7uKksPQZIjY3kBku//F+YyMDkq9jcNkl5uuop9nu81 c8v13kBLyBkA1EdCwf0gpHVjOGjgR8WtZDmjyiKd6a/aYznOWU4D9OIiVtfhuUH2xZ7i n82Q== X-Gm-Message-State: AOAM530y+N38GawB5vwX64DZG6zdm7ENSLxp3bA7mERKbRyUc4WSldII zeAAI/e9ToPPr6ecAA9bWRPEKTBFm/9+fAO7XncPBEYhvYa/bRzi4F7BXui6WZmUNuMs+FqqmFk 87jbRGFXwTday7B8lajl4uwVeDQ8eoMWRiP3UQ6SV X-Received: by 2002:a17:90b:1185:: with SMTP id gk5mr6565510pjb.113.1638283507716; Tue, 30 Nov 2021 06:45:07 -0800 (PST) X-Google-Smtp-Source: ABdhPJx/GbMjaHEEpyrXrYvb0pycmTGPDKLSCBDVw5H6za5zXROyd/rafwD0byS0pSYtAcTrnS01FdaeQMM0I0ClGUc= X-Received: by 2002:a17:90b:1185:: with SMTP id gk5mr6565466pjb.113.1638283507426; Tue, 30 Nov 2021 06:45:07 -0800 (PST) MIME-Version: 1.0 References: <20211126130141.1811848-1-tero.kristo@linux.intel.com> In-Reply-To: <20211126130141.1811848-1-tero.kristo@linux.intel.com> From: Benjamin Tissoires Date: Tue, 30 Nov 2021 15:44:56 +0100 Message-ID: Subject: Re: [RFCv2 0/8] USI stylus support series To: Tero Kristo Cc: "open list:HID CORE LAYER" , Jiri Kosina , Mika Westerberg , lkml , Dmitry Torokhov , Peter Hutterer Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Tero, On Fri, Nov 26, 2021 at 2:02 PM Tero Kristo wrote: > > Hi, > > This series is an update based on comments from Benjamin. What is done > is this series is to ditch the separate hid-driver for USI, and add the > generic support to core layers. This part basically brings the support > for providing USI events, without programmability (patches 1-6). That part seems to be almost good for now. I have a few things to check: - patch2: "HID: hid-input: Add suffix also for HID_DG_PEN" I need to ensure there are no touchscreens affected by this (there used to be a mess with some vendors where they would not declare things properly) - patch5: "HID: core: map USI pen style reports directly" this one feels plain wrong. I would need to have a look at the report descriptor but this is too specific in a very generic code > > Additionally, a HID-BPF based sample is provided which can be used to > program / query pen parameters in comparison to the old driver level > implementation (patches 7-8, patch #8 is an incremental change on top of > patch #7 which just converts the fifo to socket so that the client can > also get results back from the server.) After a few more thoughts, I wondered what your input is on this. We should be able to do the very same with plain hidraw... However, you added a `hid/raw_event` processing that will still be kept in the kernel, so maybe bpf would be useful for that at least. > > The whole series is based on top of Benjamin's hid-bpf support work, and > I've pushed a branch at [1] with a series that works and brings in > the dependency. There are also a few separate patches in this series to > fix the problems I found from Benjamin's initial work for hid-bpf; I > wasn't able to get things working without those. The branch is also > based on top of 5.16-rc2 which required some extra changes to the > patches from Benjamin. Yeah, I also rebased on top of 5.16 shortly after sharing that branch and got roughly the same last fix (HID: bpf: compile fix for bpf_hid_foreach_rdesc_item). I am *very* interested in your "HID: bpf: execute BPF programs in proper context" because that is something that was bothering me a lot :) "HID: bpf: add expected_attach_type to bpf prog during detach" is something I'll need to bring in too but "HID: bpf: fix file mapping" is actually wrong. I initially wanted to attach BPF programs to hidraw, but shortly realized that this is not working because the `hid/rdesc_fixup` kills the hidraw node and so releases the BPF programs. The way I am now attaching it is to use the fd associated with the modalias in the sysfs file (for instance: `sudo ./hid_surface_dial /sys/bus/hid/devices/0005:045E:091B.*/modalias`). This way, the reference to the struct hid_device is kept even if we disconnect the device and reprobe it. Thanks again for your work, and I'd be curious to have your thoughts on hid-bpf and if you think it is better than hidraw/evdev write/new ioctls for your use case. Cheers, Benjamin > > -Tero > > [1] https://github.com/t-kristo/linux/tree/usi-5.16-rfc-v2-bpf > >