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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 D0512C43603 for ; Sun, 15 Dec 2019 16:04:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A587B205C9 for ; Sun, 15 Dec 2019 16:04:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726282AbfLOQEr (ORCPT ); Sun, 15 Dec 2019 11:04:47 -0500 Received: from mx2.cyber.ee ([193.40.6.72]:50637 "EHLO mx2.cyber.ee" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726118AbfLOQEr (ORCPT ); Sun, 15 Dec 2019 11:04:47 -0500 Subject: Re: Regression in 5.4 kernel on 32-bit Radeon IBM T40 To: Woody Suwalski Cc: =?UTF-8?Q?Christian_K=c3=b6nig?= , "Deucher, Alexander" , linux-kernel@vger.kernel.org, Pavel Machek References: <400f6ce9-e360-0860-ca2a-fb8bccdcdc9b@gmail.com> From: Meelis Roos Message-ID: <1e6a6ccb-a7a0-4173-d667-a53eb99b8699@linux.ee> Date: Sun, 15 Dec 2019 18:04:09 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <400f6ce9-e360-0860-ca2a-fb8bccdcdc9b@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 15.12.19 05:17 Woody Suwalski wrote: > Regression in 5.4 kernel on 32-bit Radeon IBM T40 > triggered by > commit 33b3ad3788aba846fc8b9a065fe2685a0b64f713 > Author: Christoph Hellwig > Date:   Thu Aug 15 09:27:00 2019 +0200 > > Howdy, > The above patch has triggered a display problem on IBM Thinkpad T40, where the screen is covered with a lots of random short black horizontal lines, or distorted letters in X terms. > > The culprit seems to be that the dma_get_required_mask() is returning a value 0x3fffffff > which is smaller than dma_get_mask()0xffffffff.That results in dma_addressing_limited()==0 in ttm_bo_device(), and using 40-bits dma instead of 32-bits. I have the same problem on 32-bit Dell Latitude D600. > If I hardcode "1" as the last parameter to ttm_bo_device_init() in place of a call to dma_addressing_limited(),the problem goes away. Tried this on top on 5.4.0 and it helped here too. -- Meelis Roos