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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 EABEEC43331 for ; Tue, 24 Mar 2020 14:11:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BEB2820775 for ; Tue, 24 Mar 2020 14:11:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727686AbgCXOLC (ORCPT ); Tue, 24 Mar 2020 10:11:02 -0400 Received: from orion.archlinux.org ([88.198.91.70]:39736 "EHLO orion.archlinux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727289AbgCXOLC (ORCPT ); Tue, 24 Mar 2020 10:11:02 -0400 Received: from orion.archlinux.org (localhost [127.0.0.1]) by orion.archlinux.org (Postfix) with ESMTP id AE3861A6266CCB; Tue, 24 Mar 2020 14:10:58 +0000 (UTC) Received: from genesis (unknown [IPv6:2001:8a0:f254:2300:dad6:8c60:8394:88da]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (4096 bits)) (No client certificate requested) (Authenticated sender: ffy00) by orion.archlinux.org (Postfix) with ESMTPSA; Tue, 24 Mar 2020 14:10:57 +0000 (UTC) Message-ID: <3c20624ea9d88f13d6f1a768735f08a4a8a59ea6.camel@archlinux.org> Subject: Re: [PATCH v2] HID: logitech-dj: issue udev change event on device connection From: Filipe =?ISO-8859-1?Q?La=EDns?= To: Bastien Nocera , Jiri Kosina , Benjamin Tissoires , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Hutterer , Hans de Goede , Mario Limonciello , Richard Hughes In-Reply-To: <220e8421f8ee0cf80375bfc4635e3eaa2bb8daf1.camel@hadess.net> References: <20200318161906.3340959-1-lains@archlinux.org> <20200318192721.390630-1-lains@archlinux.org> <92f48f409e913299c12322d195c88792bb4e5c9c.camel@hadess.net> <220e8421f8ee0cf80375bfc4635e3eaa2bb8daf1.camel@hadess.net> Organization: Archlinux Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-pDPwtUufVHNf69huRHRz" Date: Tue, 24 Mar 2020 14:10:57 +0000 MIME-Version: 1.0 User-Agent: Evolution 3.36.0 Sender: linux-input-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org --=-pDPwtUufVHNf69huRHRz Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2020-03-24 at 15:03 +0100, Bastien Nocera wrote: > On Tue, 2020-03-24 at 13:46 +0000, Filipe La=C3=ADns wrote: > > On Tue, 2020-03-24 at 11:20 +0100, Bastien Nocera wrote: > > > On Wed, 2020-03-18 at 19:27 +0000, Filipe La=C3=ADns wrote: > > > > As discussed in the mailing list: > > > >=20 > > > > > Right now the hid-logitech-dj driver will export one node for > > > > > each > > > > > connected device, even when the device is not connected. That > > > > > causes > > > > > some trouble because in userspace we don't have have any way to > > > > > know if > > > > > the device is connected or not, so when we try to communicate, > > > > > if > > > > > the > > > > > device is disconnected it will fail. > > >=20 > > > Why is it a problem that user-space communication fails? Note that > > > sending a signal without any way to fetch the state means that it's > > > always going to be racy. > >=20 > > It failing is not the problem. The problem is knowing when the device > > is available again. Right now the only way to do that is to listen > > for > > events or periodically ping it. > >=20 > > We want to only export the HID++ hidraw node when the device is > > available but that will take a while. We will have to test and sync > > up > > userspace. I also want to write tests for the driver before, to make > > sure there are no regressions. We had a thread discussing this, IIRC > > you were in CC. >=20 > If I need to remember some old thread to know what we're talking about, > then that means that the commit message is probably not good enough... Should I put in the commit message what is planned next? > Please add some links to the relevant discussion on bug forums if > there's interesting data there too. You can find the discussion in [1][2]. [1] https://www.spinics.net/lists/linux-input/thrd2.html#65615 [2] https://www.spinics.net/lists/linux-input/msg65615.html > > > > The solution reached to solve this issue is to trigger an udev > > > > change > > > > event when the device connects, this way userspace can just wait > > > > on > > > > those connections instead of trying to ping the device. > > > >=20 > > > > Signed-off-by: Filipe La=C3=ADns > > > >=20 > > > > --- > > > >=20 > > > > v2: > > > > - Issue udev change event on the connected hid device, not on > > > > the > > > > receiver > > > >=20 > > > > --- > > > > drivers/hid/hid-logitech-dj.c | 7 ++++++- > > > > 1 file changed, 6 insertions(+), 1 deletion(-) > > > >=20 > > > > diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid- > > > > logitech-dj.c > > > > index 48dff5d6b605..282e57dd467d 100644 > > > > --- a/drivers/hid/hid-logitech-dj.c > > > > +++ b/drivers/hid/hid-logitech-dj.c > > > > @@ -1412,6 +1412,7 @@ static int logi_dj_dj_event(struct > > > > hid_device > > > > *hdev, > > > > { > > > > struct dj_receiver_dev *djrcv_dev =3D hid_get_drvdata(hdev); > > > > struct dj_report *dj_report =3D (struct dj_report *) data; > > > > + struct dj_device *dj_dev; > > > > unsigned long flags; > > > > =20 > > > > /* > > > > @@ -1447,7 +1448,9 @@ static int logi_dj_dj_event(struct > > > > hid_device > > > > *hdev, > > > > =20 > > > > spin_lock_irqsave(&djrcv_dev->lock, flags); > > > > =20 > > > > - if (!djrcv_dev->paired_dj_devices[dj_report->device_index]) { > > > > + dj_dev =3D djrcv_dev->paired_dj_devices[dj_report->device_index]; > > > > + > > > > + if (!dj_dev) { > > > > /* received an event for an unknown device, bail out */ > > > > logi_dj_recv_queue_notification(djrcv_dev, dj_report); > > > > goto out; > > > > @@ -1464,6 +1467,8 @@ static int logi_dj_dj_event(struct > > > > hid_device > > > > *hdev, > > > > if (dj_report- > > > > > report_params[CONNECTION_STATUS_PARAM_STATUS] =3D=3D > > > > STATUS_LINKLOSS) { > > > > logi_dj_recv_forward_null_report(djrcv_dev, > > > > dj_report); > > > > + } else { > > > > + kobject_uevent(&dj_dev->hdev->dev.kobj, > > > > KOBJ_CHANGE); > > > > } > > > > break; > > > > default: --=20 Filipe La=C3=ADns --=-pDPwtUufVHNf69huRHRz Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEE0jW0leqs33gyftiw+JPGdIFqqV0FAl56FOoACgkQ+JPGdIFq qV2TWRAAvWhHKnpVD7+X0n9FKziEPCKb1ACTxUHAO89vPsV6yPpoZhZqt+RvXB1u Pms8CsRYKBPmnGl5gMYBWStvSiyBsZdbYGRJC8wyAvheag86zr3Zgm8zakSXIJIa 3WOJGkp08MZxxKRLeKU/RwkSMqkPe/cq8/ZaP97lTObhx912FH/KAs7wfUAX8m9T yRVvq6rUL1W8UeGpA5V8UYCCtKfzsLjU1682HXB+gEvjACBLYR5d6Tf77DwghRm6 HiW/XTFB6nRRC+Aouj2cJixMkUK/4UCtazxaowr2JWT34Mml9gQRpwNtv/+nfLEs T/4Tcf3J9QbEEEpbozJ/rl3je4Sa9PP8p9s0raEdvv2ndZVfuwCu2qJj7p4yhJOi z59iFzzbtqBporPW9SoRgyxKnZ2o9Wj86wX4MQFxKK8culderl5inkutXtWo8ujF f0NQqpMhBz/7ZAW66Fu7g/3y63QXl9cPydjRHuHzqUYSfr7bzDi9sQNS+MZIRHFy pi0vy8Imxsq5sHOCvfNvXzvVJiZlkcX3ZiauNtAFhM+kgYXnurm3QAOVu+TxIV1I a5cQDvw/WRu8F2gz/CQiT2JKr85L873jie1lmfORek6EIrTQk/NpB2mmkuXDw5JR xJ2qq27aQlKRuu/DeNaMZcdFCQfVkGWsdGEalTSiDM0owjqTVPg= =wOd5 -----END PGP SIGNATURE----- --=-pDPwtUufVHNf69huRHRz--