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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C32B6C433EF for ; Fri, 18 Mar 2022 14:33:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233816AbiCROfQ (ORCPT ); Fri, 18 Mar 2022 10:35:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49552 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231944AbiCROfO (ORCPT ); Fri, 18 Mar 2022 10:35:14 -0400 Received: from relay3-d.mail.gandi.net (relay3-d.mail.gandi.net [217.70.183.195]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 842612CD808; Fri, 18 Mar 2022 07:33:50 -0700 (PDT) Received: (Authenticated sender: miquel.raynal@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 53E2E60009; Fri, 18 Mar 2022 14:33:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1647614029; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8lOUGQOnlujmyqKVP0r+cQLixrFJgyiaHwH43PeXgJk=; b=am/RZThV4nxuc1rCuP4WUqkPiFdNIXwe3+FGJQWPjpWd2EHFA3FI4DzPBU9l3rNuWuBtq+ of28xaVNAeDKvnLUJC+Sje3hnKnMBBjDVig/37SdFJRUwvqIlC6ZM3Sssz0ob7Alc7kf3q S6Pkzgpzfs3DZ2TasR39Ye3tDwV5LinfPL8gKHw4ORUxyMGJHPoLRZGQZb/IRHMa/mJzE3 Vu20EZDAFdjvu8w/xa/HDb87m21IxQkNI8KPYIciLPu4CFpWwobWOwkS0h9KI+LiPR3oLp Ih/AJnH4wmg0XVof3IAuwIK+aglBat0736VdN8WGowI5kgMUaegzeruWiX9e1g== Date: Fri, 18 Mar 2022 15:33:46 +0100 From: Miquel Raynal To: Andy Shevchenko Cc: linux-renesas-soc@vger.kernel.org, Magnus Damm , Gareth Williams , Phil Edworthy , Geert Uytterhoeven , Greg Kroah-Hartman , Jiri Slaby , Milan Stevanovic , Jimmy Lalande , Pascal Eberhard , Thomas Petazzoni , Herve Codina , Clement Leger , linux-serial@vger.kernel.org Subject: Re: [PATCH v2 05/10] serial: 8250: dw: Check when possible if DMA is effectively supported Message-ID: <20220318153346.152b3ff6@xps13> In-Reply-To: References: <20220317174627.360815-1-miquel.raynal@bootlin.com> <20220317174627.360815-6-miquel.raynal@bootlin.com> Organization: Bootlin X-Mailer: Claws Mail 3.17.7 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org Hi Andy, andriy.shevchenko@linux.intel.com wrote on Fri, 18 Mar 2022 15:50:12 +0200: > On Thu, Mar 17, 2022 at 06:46:22PM +0100, Miquel Raynal wrote: > > The CPR register can give the information whether the IP is DMA capable > > or not. Let's extract this information when the CPR register is valid > > and use it to discriminate when the DMA cannot be hooked up. > >=20 > > We assume existing designs either provide a valid CPR register or do not > > provide any. =20 >=20 > ... >=20 > > + if (!(reg & DW_UART_CPR_DMA_EXTRA)) > > + data->no_dma =3D 1; =20 >=20 > My question still remains: Does this bit is _guaranteed_ to be set when t= his IP > is integrated on all possible DMAs? I'll get rid of that entirely, let's just hope there is always DMA support. Thanks, Miqu=C3=A8l