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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 6FBD6C433DB for ; Thu, 25 Feb 2021 09:40:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1CB5564EC3 for ; Thu, 25 Feb 2021 09:40:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232953AbhBYJkY (ORCPT ); Thu, 25 Feb 2021 04:40:24 -0500 Received: from mail.kernel.org ([198.145.29.99]:51450 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234250AbhBYJiv (ORCPT ); Thu, 25 Feb 2021 04:38:51 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id C513064EBA; Thu, 25 Feb 2021 09:38:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614245890; bh=5buN3EC107S76JKghAcicRI28n7jlFz14jT62JQaKPU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=euBaOkbadcvUXmfC2VxZUjDjRqbhLRRIGr9iOoFZJ2l82JgzRCpRJBInxlw/tWUJd TTBSPZMLXSAccC+6x2QJmEhQNrCwFx+gvBeZBvNHgMUKRwP8OuPTGerA3pYT0LdxBA kRJCHjgNqA9y/NKEsCAxUbkq86lQ8UJOEHQcS3yHCICalSLAGdqWxdNIzGR5Zrbcbj C5Jf8/8x9yHMliTa7nd0gIsBtmcx8mfv144Vh+jOOjzsiz5MB8fwCJNqYctgvvQ6yj q9/R5rlVpQ6OFSY6IyZY/z/okNFF8w8aKrdzmT49zjKr/AGYdHd6jn1E9Gyk2rJHNA +NPUW4HmrHUrg== Date: Thu, 25 Feb 2021 10:38:01 +0100 From: Wolfram Sang To: Nikolai Kostrigin Cc: linux-i2c@vger.kernel.org, "open list:HID CORE LAYER" , "Gustavo A. R. Silva" , Colin Ian King , Dmitry Torokhov , Benjamin Tissoires , lkml Subject: Re: Need some help on "Input: elantech - add LEN2146 to SMBus blacklist for ThinkPad L13 Gen2" Message-ID: <20210225093801.GA1008@ninjato> References: <0d1eaadd-5350-63a4-fe6d-f8f357c49504@basealt.ru> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="Dxnq1zWXvFF0Q93v" Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org --Dxnq1zWXvFF0Q93v Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, > I had a preliminary discussion with Benjamin Tissoires and according to > our agreement I repost it for wider audience. > Blacklisting the device was decided to be a bad idea. > But actually I managed to get touchpad totally operational via SMBus > using a following hack: >=20 > providing a parameter to i2c_i801 driver: >=20 > modprobe i2c_i801 disable_features=3D0x2 (i.e. disable the block buffer). So, from an I2C perspective, there are two things to mention here: a) I am in the process of extending the I2C core to allow block transfers > 32 byte. This is a slow process, though, because we need to pay attention to not break userspace ABI. If this is done *and* the i801 driver supports length > 32 bytes, too, then it would work natively. If the i801 can do this, this is a question for Jean Delvare. b) I don't know Elantech HW but there are devices out there which allow configuration for the block size. Something like a bit specifying if block transfers > 32 are allowed. Or the SMBus version to support. Block transfers > 32 are SMBus 3.0+ only. If your HW does not have that, disabling SMBus is an option, too. Disabling it in the i801 driver is too much of a hammer, I'd say. Hope this helps! Happy hacking, Wolfram --Dxnq1zWXvFF0Q93v Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEOZGx6rniZ1Gk92RdFA3kzBSgKbYFAmA3b/UACgkQFA3kzBSg KbZgIw/6Amdf7SNeFb/tzaL4tGkVQsJrbp9bEb04NSYN+KcVlsRlXGz4jV6Uup5s jyGQi3Nv64TdPTm0ASUnBEgvBsmniASxiCbLKpmTwpO6IfMp+U94SbeT0l2B5Ezu PFrxoRGyX1nnolfi1SL12SlyMJlxPjS2BXtE2ZOnoSGVi8UWTC9hvJ5lNVYIKTQ4 EdBxhS78ptsrGxetlfao40+8pVFRWDSS7GtaXoNoUU5Ih71GVL4f5xWQYtKGWHJ4 6TJjHQLHDhU1r978oqC36TTflQCnuwX1uShHqMIIz3cuqiQRbyHp9s8r1acGaKd0 EtOVlLR0O3bgcdN/pFHzMxJKg6O+l4xQPdX6cD7KA6W8pNAtmRMXCSUvzZeVArO5 dXL6j1uAtSPp55oc8zGjXtvnKDc1rvsNPtLOKlOK1JD6cMPwFZYfxpWVdjeiUpv5 O9Kcf3ZW5w8CqSN5HDIU7rlJZUzYUNULGIvpNPMBp6CAcaQl7rray9QNqUM7iN4N oraCEkjtF/xa+65wGMpLSN1a03b7iGNTwVwxjNjPEXWT76ikjX6tZM4BXmRdMI/u FlpPTDWieZyEp+UEzm1a4HOxsnOQ2KpUW1YlEQk/FC3kRBBOn+DMaD21Mfz2uqCO m7oXTTNAI5w2AYfSvmLSqHrPV+ber09CV1T4i4wZUAqZuEU5X1o= =ZevR -----END PGP SIGNATURE----- --Dxnq1zWXvFF0Q93v--