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=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 849EFC43463 for ; Thu, 17 Sep 2020 20:57:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 35EAE2087D for ; Thu, 17 Sep 2020 20:57:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600376229; bh=yioVQ2V47I4LfYvG7JgQOgciS8kwofLhOenDKNaa3XQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=GVgXGB03sxCKvPokqOMDphX8+CoYzrBYbnXSqHWmmW6wbTy/dBAgTBZw0fnjMeQs8 NgNyrmv+FCvi71s2jrB7HMmJH0ju7PpcBO/Y6nmNlt80zV6BPawx5wucqfJYnQOuCL GUNKwgYtmHxERVWWvheDvjZtvQ3TOK9VCToie5Ho= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726408AbgIQU5I (ORCPT ); Thu, 17 Sep 2020 16:57:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:43578 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726180AbgIQU5I (ORCPT ); Thu, 17 Sep 2020 16:57:08 -0400 Received: from localhost (router.4pisysteme.de [80.79.225.122]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4F5A520874; Thu, 17 Sep 2020 20:57:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600376228; bh=yioVQ2V47I4LfYvG7JgQOgciS8kwofLhOenDKNaa3XQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QM28TeKuU/FZvrhw0wWzwLsDqf2A6RT82P5IJYWJo17ZTE51enNCflKAXRRtaKwdO B8dHOKgWsAG1ppdT8v/LmtqC+78QGUZ3+VXom4JrK2Vl/Mg6aMU+QpoSiB8ntzNMqM YKDgjrvVISeTCzynyfXXJaZUMyD6wMkFJEQ+M3i0= Date: Thu, 17 Sep 2020 22:57:04 +0200 From: Wolfram Sang To: Sultan Alsawaf Cc: linux-i2c@vger.kernel.org, jikos@kernel.org, aaron.ma@canonical.com, admin@kryma.net, andriy.shevchenko@linux.intel.com, benjamin.tissoires@redhat.com, hdegoede@redhat.com, hn.chen@weidahitech.com, jarkko.nikula@linux.intel.com, kai.heng.feng@canonical.com, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, mika.westerberg@linux.intel.com, vicamo.yang@canonical.com Subject: Re: [PATCH v2 3/4] i2c: designware: Allow SMBus block reads up to 255 bytes in length Message-ID: <20200917205704.GA18027@kunai> Mail-Followup-To: Wolfram Sang , Sultan Alsawaf , linux-i2c@vger.kernel.org, jikos@kernel.org, aaron.ma@canonical.com, admin@kryma.net, andriy.shevchenko@linux.intel.com, benjamin.tissoires@redhat.com, hdegoede@redhat.com, hn.chen@weidahitech.com, jarkko.nikula@linux.intel.com, kai.heng.feng@canonical.com, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, mika.westerberg@linux.intel.com, vicamo.yang@canonical.com References: <20200917052256.5770-1-sultan@kerneltoast.com> <20200917052256.5770-4-sultan@kerneltoast.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="yrj/dFKFPuw6o+aM" Content-Disposition: inline In-Reply-To: <20200917052256.5770-4-sultan@kerneltoast.com> Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org --yrj/dFKFPuw6o+aM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Sep 16, 2020 at 10:22:55PM -0700, Sultan Alsawaf wrote: > From: Sultan Alsawaf >=20 > According to the SMBus 3.0 protocol specification, block transfer limits > were increased from 32 bytes to 255 bytes. Remove the obsolete 32-byte > limitation. Sadly, it is not that easy. We are trying to extend BLOCK_MAX to 255 (SMBus 3 specs) but there are various things to be considered, especially with buffers and when passing it to userspace. Check here for the discussion (and you are welcome to join, of course): http://patchwork.ozlabs.org/project/linux-i2c/list/?submitter=3D79741&state= =3D* >=20 > Signed-off-by: Sultan Alsawaf > --- > drivers/i2c/busses/i2c-designware-master.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) >=20 > diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/bus= ses/i2c-designware-master.c > index 22f28516bca7..5bd64bd17d94 100644 > --- a/drivers/i2c/busses/i2c-designware-master.c > +++ b/drivers/i2c/busses/i2c-designware-master.c > @@ -433,7 +433,7 @@ i2c_dw_read(struct dw_i2c_dev *dev) > regmap_read(dev->map, DW_IC_DATA_CMD, &tmp); > if (flags & I2C_M_RECV_LEN) { > /* Ensure length byte is a valid value */ > - if (tmp <=3D I2C_SMBUS_BLOCK_MAX && tmp > 0) > + if (tmp > 0) > len =3D i2c_dw_recv_len(dev, tmp); > else > len =3D i2c_dw_recv_len(dev, len); > --=20 > 2.28.0 >=20 --yrj/dFKFPuw6o+aM Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEOZGx6rniZ1Gk92RdFA3kzBSgKbYFAl9jzZwACgkQFA3kzBSg KbbyuxAAtVvk4z2xbQhHrVRJqygO8JzmyOFWL1J8QCn7/cwZ+Kf1OhainyVtGkuq t36/lVl69MNwe7DNumQg3UdxpmSHdGTwd0QYkVRrHkQIEuCZEsvys7cWXcddvB/E v/rSyY4XQsJBK1+NKQxEBe0CdZ3geZoIMcBYNP67DF5qTH41G7Hgo/PIoBAfXyL8 xqfpnr1zydL7ZtF4tRQ28moIbtuXO7sCxac8OpiDSFgJrLOby2eyw24nchu6aZL7 ZVhCb71CeAmVrnRWHoma0HplPvxBGjR97qPfb7Bpsl42A1F4bk/didb3xIRzQvtt v6S1xQy6voytuBYzy/d1y6yss0aPeF7MZ4/W/953hspriVcd+D0kvHP8JyzG0AYo tMmIUdDV18k/v/21IFynhvxXcoSu3+BF2tAcbE3tkSCu5YSfH31EnJESVKAszlxW yCRgjpwN6cgcvlun4OHrRU+E2gnYVbY//Byt6zWUIEBt3QWhWALPhIHuHrLep4EZ gnBIadvjYZ5zL5lyUo+tQd+QLBtvkUV14WdxQXfGFbqokmZXjGlrH7+YTjuZm/2p U3Tft0oXVoT2ZSICejyCHEk/eYP1r4cEH5xupU/LPmnkIcxlQevQDbjek9+c23BU FRGQMvoYApPk2xcrfBau9ailDzUedB9gw7otHdP5+pCz599a3iI= =GStr -----END PGP SIGNATURE----- --yrj/dFKFPuw6o+aM--