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 367D7C61DB3 for ; Fri, 13 Jan 2023 07:24:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240731AbjAMHYT (ORCPT ); Fri, 13 Jan 2023 02:24:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54270 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241253AbjAMHXo (ORCPT ); Fri, 13 Jan 2023 02:23:44 -0500 Received: from muru.com (muru.com [72.249.23.125]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id A522972886; Thu, 12 Jan 2023 23:14:32 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id 2210F80FA; Fri, 13 Jan 2023 07:14:32 +0000 (UTC) Date: Fri, 13 Jan 2023 09:14:30 +0200 From: Tony Lindgren To: Arnd Bergmann Cc: Aaro Koskinen , Lukas Bulwahn , Janusz Krzysztofik , Krzysztof Kozlowski , linux-arm-kernel@lists.infradead.org, Linux-OMAP , linux-usb@vger.kernel.org, linux-samsung-soc@vger.kernel.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4] usb: remove OMAP USB Device Controller and OHCI support for OMAP1/2 chips Message-ID: References: <20230112083746.9551-1-lukas.bulwahn@gmail.com> <20230112083746.9551-4-lukas.bulwahn@gmail.com> <3f2663ff-ff3f-4632-853a-ba4d38df9701@app.fastmail.com> <20230112140524.GK730856@darkstar.musicnaut.iki.fi> <179739a0-5d75-412b-964b-16d5cb6d306d@app.fastmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <179739a0-5d75-412b-964b-16d5cb6d306d@app.fastmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Arnd Bergmann [230112 14:31]: > On Thu, Jan 12, 2023, at 15:05, Aaro Koskinen wrote: > > On Thu, Jan 12, 2023 at 11:19:53AM +0100, Arnd Bergmann wrote: > >> On Thu, Jan 12, 2023, at 10:53, Tony Lindgren wrote: > >> > >> So if we want to kill off the old DMA stuff there is actually > >> a choice between either making omap_udc PIO-only or converting > >> it to use the standard dmaengine interface. > > > > I use this driver on Palm TE and 770, and without it those boards would > > be useless for my use cases. Also DMA doubles the throughput, probably > > also power usage is smaller. > > Ok, if the performance is important, converting to dmaengine > is probably best. Do you know if this is just a straightforward > replacement of the function calls, or are there technical reasons > why it's not using the dmaengine interface yet? Yes I agree dmaengine is the best solution. Seems like this is the last driver using the old api that never got updated probably because it's not used on the newer SoCs. I don't think there are any technical reasons to not use dmaengine here. FYI, the last blocker for dmaengine use was for drivers using port_window that got added with the drivers/usb/musb/tusb6010_omap.c dmaengine conversion a few years back. Regards, Tony