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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 08508C47404 for ; Wed, 9 Oct 2019 14:09:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D4CC021848 for ; Wed, 9 Oct 2019 14:09:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ItHuOga3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731192AbfJIOJK (ORCPT ); Wed, 9 Oct 2019 10:09:10 -0400 Received: from mail-io1-f68.google.com ([209.85.166.68]:46898 "EHLO mail-io1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729883AbfJIOJK (ORCPT ); Wed, 9 Oct 2019 10:09:10 -0400 Received: by mail-io1-f68.google.com with SMTP id c6so5148905ioo.13; Wed, 09 Oct 2019 07:09:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=WrZAk5gJkER1O1xn2TCucF4dEQP6LH4cuHnhethSJ8M=; b=ItHuOga3a0OFHONWEPlKRcF5GP+jCkkvEjryppl8BJ8T5PIdxFMrWrT5UTLk5uy83g 5OCtgnfkD45s3QNWiV9VXifVJKgc4MVZk7OCN8YYk5+n/tO/GCZQOlbp07EjVaQTeJ7B l5K1vBtEaTyy/6aad+Fkc9HCzCa36sg5CZ8Cp6SeS69iQuVpkoSW9nyePKlQ/RvI/92n JtYgdXEDo0Ot8wEC28eYJGpgm2O+3YLxJVYMlMOe7MVuXg2O+08Q2PQdIiu8ZihNX/eJ Iu4oJlsa2gpQ7Dh9R3UEkO7684Ha862Hr66jV7E+E9zui0mE7uFLCMUHnb6uh4+ZQw/V W4GA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=WrZAk5gJkER1O1xn2TCucF4dEQP6LH4cuHnhethSJ8M=; b=PW3A0k51Zhf+uRAVAzI57KigqxmJ7UIiUTGvjBowua9tmGBEwCStU/iuVUwDu559xN /tAGSKd2x0iLp09/GdrFBCCI99i/TFh6O7+q0QkyJArI7VPaZhWpOKEfZEIvxBEVLD48 lGCREr288CNnVLhvlaZ68A2M7OgPPAyt/d1E8HkHTbSHMYsC3YzA2UKM3a84EIf7EDmb i5a40fHO1Rb2RtcZ7aJiJeA81FNA5EC25AfZjHKLIgpBTqX/JMUy8drNCWqZrjnskRf+ yDYWgTxh3d1vl9zgcS3ugYYBBw3PMnV2iJ547uOSACSrcDQsQABQXp/5+VDbO4XY7YdZ Yjrg== X-Gm-Message-State: APjAAAVrhm3ZzmUo8vQqbSVJ+GfIKqVHYt1PHbKk/2fepvBOK8a23AjL iPOl5HAhGA2vyaZ2uVYlfVsgtC4ipfsRI6XzSJI= X-Google-Smtp-Source: APXvYqydLUN9gXf0yzgt77Zbc8y4VKX5W7xoCP1U5BA0C169qM9cU6AyjGMeW1wmLxpllA1iM/VBGRA6ZSvHF9wowLw= X-Received: by 2002:a02:a11e:: with SMTP id f30mr3223182jag.95.1570630148852; Wed, 09 Oct 2019 07:09:08 -0700 (PDT) MIME-Version: 1.0 References: <3d5b3a12-a21c-f464-e7d1-252ccd768ff8@ti.com> In-Reply-To: <3d5b3a12-a21c-f464-e7d1-252ccd768ff8@ti.com> From: Adam Ford Date: Wed, 9 Oct 2019 09:08:57 -0500 Message-ID: Subject: Re: Serial 8250 DMA Broken on OMAP3630 To: Vignesh Raghavendra Cc: Greg Kroah-Hartman , Jiri Slaby , Andy Shevchenko , Douglas Anderson , Tony Lindgren , Yegor Yefremov , linux-serial@vger.kernel.org, Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 9, 2019 at 8:42 AM Vignesh Raghavendra wrote: > > Hi Adam, > > On 06/10/19 10:34 PM, Adam Ford wrote: > > Has anyone else had any issues using the CONFIG_SERIAL_8250_DMA on the OMAP? > > > > I can use the DMA on the legacy, omap-serial driver, but when I enable > > the DMA on the 8250-omap driver, I get missing frames in Bluetooth. > > > > The older driver seems to have an ISR that seems to address a variety > > of items compared to the very tiny ISR for 8250-omap.c. > > > > I am not exactly sure where to start, but if someone has any > > suggestions on how I can troubleshoot, please let me know. As of now, > > I have to disable CONFIG_SERIAL_8250_DMA to get the Bluetooth > > connected to UART2 operational on a DM3730 at 3,000,000 baud, but it > > appears to work just fine after some patches I just submitted for > > handling RTS/CTS. The legacy omap-serial driver works fine with DMA. > > > > Mainline omap-serial does not support DMA (evident from lack of > dmaengine API calls) and therefore is not a regression. So OMAP3 UART > DMA was never tested at least with 8250 driver. > I am not sure enabling UART DMA on OMAP3 would be a trivial job. We need > analyse of whether all erratas workarounds are implemented and see if > there any difference wrt DMA integration itself. Do we know if UART DMA > ever worked on OMAP3 previously? Can we disable CONFIG_SERIAL_8250_DMA from omap2plus_defconfig? As of right now, it's the only way I can use the Bluetooth. There are #ifdef's in the 8250-omap driver, so it looks like some of the hooks are there, but if it's incomplete, it seems like we shouldn't enable this config option by default yet. adam > > > adam > > > > -- > Regards > Vignesh