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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY 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 E1FC3C43387 for ; Wed, 26 Dec 2018 10:19:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AFC89218C3 for ; Wed, 26 Dec 2018 10:19:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726686AbeLZKTF (ORCPT ); Wed, 26 Dec 2018 05:19:05 -0500 Received: from mailgw02.mediatek.com ([210.61.82.184]:61831 "EHLO mailgw02.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726172AbeLZKTF (ORCPT ); Wed, 26 Dec 2018 05:19:05 -0500 X-UUID: 15faf0724f9f490aae9a4cd03de26b4b-20181226 X-UUID: 15faf0724f9f490aae9a4cd03de26b4b-20181226 Received: from mtkcas08.mediatek.inc [(172.21.101.126)] by mailgw02.mediatek.com (envelope-from ) (mhqrelay.mediatek.com ESMTP with TLS) with ESMTP id 454183028; Wed, 26 Dec 2018 18:18:57 +0800 Received: from MTKCAS36.mediatek.inc (172.27.4.186) by mtkmbs03n1.mediatek.inc (172.21.101.181) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Wed, 26 Dec 2018 18:18:56 +0800 Received: from [10.17.3.153] (10.17.3.153) by MTKCAS36.mediatek.inc (172.27.4.170) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Wed, 26 Dec 2018 18:18:54 +0800 Message-ID: <1545819534.28871.93.camel@mhfsdcap03> Subject: Re: [PATCH v7 1/2] dmaengine: 8250_mtk_dma: add MediaTek uart DMA support From: Long Cheng To: Nicolas Boichat CC: Vinod Koul , Randy Dunlap , "Rob Herring" , Mark Rutland , "Ryder Lee" , Sean Wang , "Matthias Brugger" , Dan Williams , Greg Kroah-Hartman , Jiri Slaby , Sean Wang , , , "linux-arm Mailing List" , , lkml , , , Yingjoe Chen , YT Shen , Zhenbao Liu Date: Wed, 26 Dec 2018 18:18:54 +0800 In-Reply-To: References: <1545701209-6884-1-git-send-email-long.cheng@mediatek.com> <1545701209-6884-2-git-send-email-long.cheng@mediatek.com> <1545739611.28871.77.camel@mhfsdcap03> <1545806121.28871.88.camel@mhfsdcap03> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit MIME-Version: 1.0 X-MTK: N Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2018-12-26 at 17:28 +0800, Nicolas Boichat wrote: ...... > > > > > > +static int mtk_uart_apdma_device_pause(struct dma_chan *chan) > > > > > > +{ > > > > > > + /* just for check caps pass */ > > > > > > + return 0; > > > > > > +} > > > > > > + > > > > > > +static int mtk_uart_apdma_device_resume(struct dma_chan *chan) > > > > > > +{ > > > > > > + /* just for check caps pass */ > > > > > > + return 0; > > > > > > +} > > > > > > Why do you need these? Seems wrong to advertise device_pause/resume > > > (and the caps) if we don't actually support that? > > > > > > > in serial 8250_dma.c file, when request DMA, will calll > > 'dma_get_slave_caps' to get the caps. and the will check caps.cmd_pause. > > the pause is device_pause. our device can't support the functions. but > > to check pass, need add the fake function. or you can give better > > comments. thanks. > > Well, then I guess this is a hack... I'm not too familiar with > 8250_dma.c, but I guess that if it requires pause/resume to be > implemented, then we should implement them, not just stub them out... > > Is this something that can be implemented with 8250_mtk DMA? > the HW can't support it. > Also, I don't see where you need resume, so maybe implementing pause is enough? > yes. pause is enough. for symmetry, add resume function. anyway, the pause function need to keep. > > > > > > + > > > > > > +static void mtk_uart_apdma_free(struct mtk_uart_apdmadev *mtkd) > > > > > > +{ > > > > > > + while (list_empty(&mtkd->ddev.channels) == 0) { > > > > > > + struct mtk_chan *c = list_first_entry(&mtkd->ddev.channels, > > > > > > + struct mtk_chan, vc.chan.device_node); > > > > > > + > > > > > > + list_del(&c->vc.chan.device_node); > > > > > > + tasklet_kill(&c->vc.task); > > > > > > + } > > > > > > +} > > > > > > + > > > > > > +static const struct of_device_id mtk_uart_apdma_match[] = { > > > > > > + { .compatible = "mediatek,mt6577-uart-dma", }, > > > > > > + { /* sentinel */ }, > > > > > > +}; > > > > > > +MODULE_DEVICE_TABLE(of, mtk_uart_apdma_match); > > > > > > + > > > > > > +static int mtk_uart_apdma_probe(struct platform_device *pdev) > > > > > > +{ > > > > > > + struct mtk_uart_apdmadev *mtkd; > > > > > > + struct resource *res; > > > > > > + struct mtk_chan *c; > > > > > > + unsigned int i; > > > > > > + int rc; > > > > > > + ......