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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS 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 09651C43381 for ; Fri, 22 Mar 2019 13:15:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C277B2183E for ; Fri, 22 Mar 2019 13:15:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="QeXqNMZh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729920AbfCVNPE (ORCPT ); Fri, 22 Mar 2019 09:15:04 -0400 Received: from lelv0143.ext.ti.com ([198.47.23.248]:60492 "EHLO lelv0143.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729753AbfCVNO5 (ORCPT ); Fri, 22 Mar 2019 09:14:57 -0400 Received: from fllv0034.itg.ti.com ([10.64.40.246]) by lelv0143.ext.ti.com (8.15.2/8.15.2) with ESMTP id x2MDEiYd122726; Fri, 22 Mar 2019 08:14:44 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1553260484; bh=p186SIZOVCdmajVPM3qYi1henRAdn/qJaKsCmV3CVFQ=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=QeXqNMZhax2pxOW3BpOs2+wQno8BbG9SpNJtOz42Mj6CPSxxHg7kygiPJztW0Ioq0 6V/0mShDnQ7/I74uABjnCWz2gOKTljko1R2KtmRz64PrJYpo4doLBmtyUrC9Wc71sr pY44Qx4EUo81EZBa0vq076H4xxsZV9I8IACAg5YI= Received: from DLEE113.ent.ti.com (dlee113.ent.ti.com [157.170.170.24]) by fllv0034.itg.ti.com (8.15.2/8.15.2) with ESMTPS id x2MDEiuN104752 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 22 Mar 2019 08:14:44 -0500 Received: from DLEE115.ent.ti.com (157.170.170.26) by DLEE113.ent.ti.com (157.170.170.24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5; Fri, 22 Mar 2019 08:14:43 -0500 Received: from dflp32.itg.ti.com (10.64.6.15) by DLEE115.ent.ti.com (157.170.170.26) with Microsoft SMTP Server (version=TLS1_0, cipher=TLS_RSA_WITH_AES_256_CBC_SHA) id 15.1.1713.5 via Frontend Transport; Fri, 22 Mar 2019 08:14:43 -0500 Received: from [192.168.2.6] (ileax41-snat.itg.ti.com [10.172.224.153]) by dflp32.itg.ti.com (8.14.3/8.13.8) with ESMTP id x2MDEfZV021486; Fri, 22 Mar 2019 08:14:42 -0500 Subject: Re: [PATCH v2 08/15] drm/bridge: tc358767: Increase AUX transfer length limit To: Andrey Smirnov , CC: Archit Taneja , Andrzej Hajda , Laurent Pinchart , Andrey Gusakov , Philipp Zabel , Chris Healy , Lucas Stach , References: <20190322032901.12045-1-andrew.smirnov@gmail.com> <20190322032901.12045-9-andrew.smirnov@gmail.com> From: Tomi Valkeinen Message-ID: <7dbccf61-29fb-a6df-7f54-fd7c29bba57f@ti.com> Date: Fri, 22 Mar 2019 15:14:41 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190322032901.12045-9-andrew.smirnov@gmail.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/03/2019 05:28, Andrey Smirnov wrote: > According to the datasheet tc358767 can transfer up to 16 bytes via > its AUX channel, so the artificial limit of 8 apperas to be too > low. However only up to 15-bytes seem to be actually supported and > trying to use 16-byte transfers results in transfers failing > sporadically (with bogus status in case of I2C transfers), so limit it > to 15. 16 is the limit from the DP spec. I agree, 8 looks odd. 15 looks odd too, so I think it warrants a comment there in the code. Does 15 byte transfers ever work? Or mostly works but sometimes fails? Tomi -- Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki